I’m back home in Detroit for a wedding, and instead of getting a press vehicle, I did what I usually do: I borrowed a car from my friend Jamie. This time, instead of his 2004 330,000 mile Mazda MPV minivan or his 2006 350,000 mile Pontiac Vibe, I have his fourth-gen Toyota 4Runner, and though it has 280,000 miles on the clock, it reminds me a lot of the 265,000 mile Lexus LX470 I once owned. Why? Because it drives like a dream in a way that very, very few 250K+ mile cars can; it’s really remarkable. What’s also remarkable is how the impressive way the car looks and drives contrasts with what lurks below its shiny body.
I don’t like to stereotype, but I will say that many of the best high-mileage cars I’ve ever driven happen to have been Japanese (the three I mentioned in the last paragraph, for example), and I’d say the very best of the best have been 4.7-liter V8 Toyotas. Though I think timing belts are garbage, the timing belt-equipped 2UZ-FE engine found in my old Land Cruiser was absolutely sensational for something that had 265,000 miles on it; it sounded like a brand new engine. That motor, combined with an Aisin automatic transmission, decent overall build quality, and nice exterior paint, yielded a vehicle that felt to me almost like it was new. Think about that for a second: A 265,000 mile car that feels similar to a new car!
I have driven more reliable cars than that Land Cruiser or the Toyota 4Runner that is the subject of this article. Any of my Jeeps equipped with the unkillable and truly reliable 4.0-liter straight six bolted up to an Aisin AX-15 manual will run and drive longer than these Toyotas and with less maintenance, but boy, they sure as hell won’t look as good doing it. And maybe that has to do with how Toyota owners tend to maintain their cars vs. how Jeep owners do, and it could also have to do with the residual value of a Toyota vs. that of a Jeep.
I won’t pretend to know all the factors in play, but what I will tell you is that there are undoubtedly more good-looking, ridiculously high-mileage Toyotas than there are decent-looking, ridiculously high-mileage Jeeps. I don’t think anyone will argue against me, there.
That brings me back to my friend Jamie’s 4Runner. This thing is an absolute cherry. The black paint looks great even after over 20 years, the interior — whose seats I assume have been freshened up, though I bet most of the rest is untouched — looks gorgeous. The body looks completely rust free.
And then you get behind the wheel. The 4.7-liter 2UZ-FE just sings. There’s a tiny exhaust leak that I can hear when the engine is cold, but once the vehicle has been running for a few minutes, the driving experience makes it seem like the vehicle just came off the showroom floor. The engine is silky smooth, and will accelerate the 4Runner faster than I expected; the five-speed Aisin A750E shifts perfectly, with no weird crashing or stuttering; the seats are cushy; the steering is tight. Yes, much of this has to do with how well Jamie maintains his cars, but some of this is just classic Toyota 4Runner/Land Cruiser.
If you pay the money to maintain them, the things just drive and drive and drive, and they do so in a way that has swagger. Their ability to not look like shit despite having gone through 260,000 miles of salty, slushy, icy Michigan Wintry Hell is unparalleled.
The result is that few vehicles ever made hide their danger like a Toyota 4Runner can.
Again, look at how nice this machine looks. It’s so shiny, its suspension stands perfectly level, the interior is awesome. My partner who’s with me on this Detroit thinks it’s a surprisingly nice machine, and she’s right! Except, she hasn’t looked underneath:
It looks like the Titanic down there! The frame is completely rotted out, especially the bottoms of the box-sections and the body mounts.
 
Look at how much rust Jamie pulled out of his frame!:
This, by the way, is not atypical for a body-on-frame Toyota. It wasn’t that long ago that Toyota agreed to spend over $3 billion recalling 2005–2010 Tacomas, 2007–2008 Tundras, and 2005–2008 Sequoias do to frames that were prone to severe corrosion. Toyota actually replaced the frames of these vehicles in what has to be one of the most absurd recall of all time (I mean, you’d think the company might as well just give the owners new trucks, but somehow frame replacement made sense). A few years ago there was news of a Class Action suit against Toyota due to 2003-2009 (fourth gen) 4Runners rusting out prematurely, and looking at Jamie’s vehicle, I understand why.
The vehicle looks so damn good, and it drive so well. But hot damn is it a rustbucket! Some of this is just a product of this vehicle having been driven in ridiculously adverse, salty, wintry conditions in Michigan and Illinois (seriously, even the brake lines rusted out), so I’m not going to go so far as to say “Toyota frames are rusty garbage,” but I will say that nobody can maximize the contrast between how badly rusted a car is and how beautiful it looks and drives like Toyota can with a 4Runner.
I mean damn, I could not believe my eyes when I stepped out of that smooth-running 4×4 and slid underneath. Luckily, Jamie has completely replaced all the brake lines, and fixed some of the rust:
But still: Yikes!
The Toyota 4Runner Traces Its Roots Back To A Long-Forgotten Camper
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I Crawled Under The 2025 Toyota 4Runner To Look At The Hardware. Here’s What I Found
Yikes! Speaking of rust, my Astra’s brake dust sheilds were held together by hopes and dreams and I finally ripped the second one off when changing the rusted to hell shocks (the first one knocked off when I nudged it when installing a wheel a week or so prior). Hopefully the new shields come in soon but it may be mid October until I can actually get to replacing them. The rust belt is so much fun 🙂
I think the kids are calling “held together by hopes and dreams” “wifi.”
Bluetooth
We found our Gen Z’er!
I was just going to say what Sklooner said: my Ranger’s crossmember was bluetooth, apparently
My dad’s old 95 D21 had a bluetooth rear axle mount. One day we came around the corner to the house and felt a little jolt and when we got into the driveway he asked me to look at the wheel and right above the wheel was a rusty chunk missing from the frame where the axle attached
We say it like that because we have no hopes or dreams.
This just looks like any 8+ year old car in Ontario that hasn’t ever been oil sprayed. I get not necessarily having to do it in other places but anywhere that experiences winter, it’s a literal vehicle saver.
Lol my Idaho cars (many of them 30+ years old) have been driving through winters their entire life without a single oil undercoating and most of them don’t even have superficial rust.
Winter isn’t what rots cars. Criminally excessive overuse of salt starts surface rust, and high humidity and rainfall the rest of the year is what turns that surface rust into structural rot. We have winter in Idaho, but not much salt and extremely little humidity and rainfall for almost all of the year.
“No Car Can Hide How Dangerous It Is Like A 300,000 Mile Toyota 4Runner Can.”
GM’s plastic-bodied cars would like a word with you. As gorgeous as the S-series always looks, there are several hidden areas that rust out. Including *three* of the control arm sockets (which aren’t as easily patched as the examples shown in this article).
Breaking the middle section of a frame makes a bad day, but it’s much less likely to kill you than losing a front control arm. And the 4Runner will eventually show visible rust on the outside, unlike the plastic-bodied cars. Maybe the 4Runner can have runner-up status.
Or would that be 4Runner-up status?
But those cars kinda fall apart elsewhere, right? Like, does the paint hold up well? The interiors? Dashboards?
Meh. The interiors from that era of GM product don’t degrade much. They start out mediocre, and 200,000 miles later they’re still mediocre. In math terms, the derivative is zero (or close to it). The paint holds up pretty well (better than other GM products of that era, and much better than the underbody). Neither one gives a real indication of how safe or dangerous the underside is, which is unfortunate
I say this having owned 4 of these cars, and having been caught off guard the first time I needed to repair one (after that I knew what to look for). It’s really easy to miss, even for a gear head. The Toyota frame rail is comparatively easy to inspect, so you can know what you’re buying just by spending a moment looking underneath.
However – I have little doubt that this 20-year-old high-mile Toyota rides more nicely than a 30-year-old high-mile Saturn!
Saturns and 4runners are not really comparable.
A better comparison would be a Trailblazer BOF or a Tahoe. Those two also had rust issues as well…and I DO NOT want to hear Toyota fixed the rust issues.. so they are the best. NO. They had a frame lawsuit also.
well, those Toyotas are known to lose control arms and ball joints on the run. My in-laws 99 Tacoma have had both replaced at different times. The difference was rust had already appeared on the roof and around the CHMSL. Mind you, there is no snow right here but the Pacific salt does its thing at a slower pace.
I’ve also seen a handful of perfectly looking Tundras and Sequoias on the side of the road with one of the front tires stripped out. I can’t recall 4Runners, though
A lot of the reason for ball joint failure in early Tacomas and 4Runners is because they don’t show wear as easily as others (I’m not sure exactly why). You need to visually look for any play in the ball joint instead of just trying to rock the tire, as the ball joint will fail long before play can be felt by a traditional check.
The real question everyone wants to know the answer to, could $7k worth of PPF have saved this 4Runner from such a fate?
No, but Krown undercoating would have definitely helped.
I’ve become a fan of WoolWax. And it smells so nice. Not sure if it’s economical if you have to pay somebody to apply it every couple years, but for the self sufficient, it’s great stuff.
I prefer CorrosionFree3000, but yes, undercoating goes a long way. I live in the Ontario salt belt so I’m unfortunately very familiar
Damnit I TOLD you to get the Trucoat!!!
They put that Truecoat on at the factory.
So they say.
Now It’ll cost you a heck of a lot more than $500!!
Let’s talk about rust-proofing. These Colecos will rust up on you like that.
In before the Ameriaan Fanboi’s blame Toyota… the faulty frames were made by Dana under contract to Toyota…. Toyota successfully sued them for failing to meet the specifications.
Dana Corp of beautiful Maumee, Ohio has been ordered to pay $25 million to Toyota for problems with parts provided by Dana to Toyota which resulted in the 1995-2000 Tacoma pickup frame-rust recall.
https://www.torquenews.com/106/dana-corp-ordered-pay-toyota-25m-frame-rust-issues
Yes, it’s quite common for recalls to involve failure of a part sourced from a supplier.
Takata!
Gesundheit
The OEM is still responsible. Supplier quality control is a thing. If Dana provided frames that were not to specification, Toyota is ultimately responsible to the customer.
And Toyota took responsibility, didn’t they?
sure they did. Last time I saw $3B >>>> $25M
“In before the Ameriaan Fanboi’s blame Toyota”
Are timing belts really that loathsome? I’d prefer to change a timing belt then deal with chain guide failure.
You are correct.
Compared to an engine that requires no timing service, yes, it really is that loathsome. There’s a reason timing belts are gone.
Gear driven cams are few and far between. Probably for reasons, like cost.
Honda’s RC45 engine (and it’s later iterations) stands out for me as a beautiful and beautiful sounding engine.
I do love a timing gear, though yeah, they’re loud, and also, for overhead cam engines, they’re just not feasible.
V10 TDI’s
[cringe!]
I’ll be in my bunk…
That Honda engine, and later VFR engines, are OHC. But it does have a characteristic whine to it as your rev it up.
The 300-6 in my 92 F250 has a phenolic timing gear. It’s apparently the one weak spot in that whole design.
Early Iron Dukes used a nylon cam gear while the crank gear was steel. No wonder why they switched to a timing chain later on.
Gear driven cams are far and few between *on the kinda of cars you’re probably thinking of*.
They’re actually relatively common on pickups, the Ford 300 has a gear drive cam and so does every 3/4 ton diesel. Anything bigger than an f350 always has a gear drive cam, they are universal in medium and heavy duty applications.
So why aren’t timing shafts a thing? Why chains which can stretch and need tensioners?
Gear driven cams in a modern pass car would need to be helicals for noise considerations, which introduces the need for thrust bearings and assorted support all adding length (width) and weight. Although some chain driven cam systems have had wear issues, the current versions seem to be pretty robust. Also the lube oil specs have been upgraded to help chain/sprocket life.
So use a herringbone gear:
A herringbone gear, a specific type of double helical gear,[1] is a side-to-side, rather than face-to-face, combination of two helical gears of opposite hands.[2] From the top, each helical groove of this gear looks like the letter V, and many together form a herringbone pattern (resembling the bones of a fish such as a herring). Unlike helical gears, herringbone gears do not produce an additional axial load.
Like helical gears, they have the advantage of transferring power smoothly, because more than two teeth will be enmeshed at any moment in time. Their advantage over the helical gears is that the side-thrust of one half is balanced by that of the other half. This means that herringbone gears can be used in torque gearboxes without requiring a substantial thrust bearing.
https://en.wikipedia.org/wiki/Herringbone_gear
That’s what double helical gear sets are for! (When you’re spending unlimited $$)
Why would it need unlimited $$ when it’s just two mirrored half thick helical gears stuck together?
Gear driven cams in passenger cars exist, yes they use helical gears, no it’s not a problem. The camshaft already has thrust bearings on it, and the cam drive carries relatively little torque so the axial forces from the helical gear aren’t that large.
I imagine it must suck if you are wrenching on as many cars as you do, but the longevity of modern belts are underappreciated miracles. The maintenance schedule on the 1.6L Ecoboost doesn’t say to replace the timing belt until 150,000 miles! Heck, even the accessory belt says just to give it an inspection at 100,000 with no mandatory replacement. These are effectively lifetime belts for most consumers these days.
I owned a Fiesta with the non-Ecoboost version of the 1.6 and from what I recall in the forums that long interval was a stretch to say the least. Personally I had mine done at 90K and had the water pump done at the same time. There were a few horror stories from a few owners having the belt snap before 150K and that seems to be the case with many other high interval TB regardless of brand.
The main reason some brands extended their TB intervals was to claim lower maintenance costs. Some of these TB actually have much shorter lifespans per the manufacturer. Just have a look to what Continental or Gates have to say about their particular belts. If I recall one of these was Ford’s supplier.
No wonder why Honda and VW call for a lower interval. Not sure what Toyota interval is but I guess it’s quite shorter than Ford’s
My mom’s got a 2008 4Runner Urban Runner with just over 200K on it. She’s still driving it to AZ and TN and LA and TX and everywhere else. Right before she retired I mentioned she should save up some money in case it needed replacing. I mean it was over 10 years old at that point so you should be expecting it anyways, but it’s still trucking.
In the decade plus she’s owned the thing the biggest problem she’s had with it is the rubber button to open the tailgate did that thing where the rubber depolymerized and “melted” and got all over absolutely everything. But under the hood, no problems. *touch wood*
Body on frame Toyota’s made in the US suffer from rust issues. Body on Frame Toyotas made in Japan (GX, Landcruiser, 50% of older Sequoias) do not suffer from the same rust issues as the US models.
Do they salt the roads in Japan?
None of these 4runners were made in the U.S.
So… nope
This was about a singular 4runners rust, any one vehicle can not live up to it’s reputation. However the idea that floats around of BoF Toyotas ALL having rust issues are not true. The American made frames were the ones subject to recall, and all the associated problems, but the foreign built frames act like every other manufacturer’s frame and rust at appropriate levels for the locale.
Vehicles also don’t survive on the road in Japan quite as long as in the US, on average, they get junked (or exported as used cars) about 4 or 5 years earlier than here, which prevents some age related maladies from showing up in large numbers.
If you find a cheap land cruiser the odds are the frame is completely gone. There are literally tons of these on FB marketplace everyday.
and every single one of those has done close too or over 300k miles over 20-30 years. That is natural wear and tear for anything made of steel that interacts with water and/or salt.
My ’04 GX would have liked a word. As would have many others
Land Cruisers and GXs DO SUFFER from rust issues…you can go and search it up.
Even with that much rust it’s still too good for you LOL
Also, Dana supplied rusty frames to both Ford and Toyota. The difference is that Toyota used the money to fix the problem, while Ford tried to pocket the money.
For the exhaust, I’m sure Borla makes a nice replacement for it, and it’s 304 so it will never rust 😀
I think it’s mint!
Ford sells a lot more than Toyota did, so they cannot SIMPLY fix every single one on the road…Toyota did the job, and they RAISED the costs of their products to do it.
Glad you got to be near some of the best rust in the United States, David. I know of your fondness for that stuff. It’s like getting citrus fruits in California or chocolate in Switzerland. Sometimes you have to go back to the motherland for the best rust. Make sure you take a supply back to California. They have no idea what they’re missing there.
Rust to David is like native soil to a vampire.
I hear he has a special Jeep filled with the stuff in the Galpin parking lot he naps in sometimes.
He’s a rust vampire?
He’s SOMETHING, that much we know for sure.
I’m guessing Elise (not her real name) found out this weekend that spending time with that much rust has the same effect on David that’s usually attributed to eating oysters. Lots and lots of oysters.
It’s USDA Prime Choice Grade A+ out here!
Not gonna lie, I thought that was a giant hairy nug on a shovel for a second there.
Phew, thought for a moment you and Elise drove it around pre-repairs. I give Jamie credit for fixing that up. I give up on them when they start to look like that.
Bought a rust free 99 Cherokee with 250k miles that lived most of its life in VA. There aren’t many vehicles I’d buy with that mileage but, like David, I have faith in the 4.0 drivetrain. It’s now retired on Cape Cod for dump runs and trips to the beach, lucky to get 1000 miles a year.
I don’t get it. David swears by the 4.0 and its unkillable nature, but he has had, what? three of them run lean and grenade? I know plenty of people that have had lean conditions that ended those motors. I know I am just anecdotes here, but I don’t get how he still believes that with his personal experience being so bad.
It’s a Jeep Thing(tm)
I’ve never had a 4.0 let me down. I’ve bought a few Jeeps with poorly-maintained cooling systems, but even those couldn’t kill the motors. The only time I actually straightup killed a 4.0 was when I drove through a swamp and hydrolocked my 250K mile XJ’s original motor! Man that was silly.
Sorry, I didn’t think you would see this. I said the same thing below. Apologies.
the 2006 non lubricated “Distributorless timing distributor, TUPY heads and a few freeze plugs sending themselves are the major issues I have ran into on the 4.0.
Lean conditions? I don’t recall David ever having had issues with that, and I have never heard of that happening.
My family has put a couple hundred thousand miles on several 4.0s and the only issue we have had even kind of related to the engine is the bad motor mount design used in XJs. Well, that and a bad oil pump in the (severely abused) Comanche. I recently had to replace a 35-year-old injector O ring if you want to call that an engine problem?
Jeep 4.0s, and the earlier 258 that’s basically the same engine, are legendarily dependable motors. We have one with 230k miles and counting because it still runs like a top. Come to think of it, that one has had an oil pan gasket and a rear main seal at some point in the last 30 years. My point stands that the engines are highly durable and dependable.
Pretty sure these pictures just gave me tetanus.
GMT800 Pre-AFM/DFM is pretty decent, but they always rust around the cab corners and usually around the wheel wells. Testament to this is the amazon plastic rust covers. they would not make them if the vehicles did not survive as lng as they do. Mine is around 280K and runs well. AC works, and 4WD is functional. I only kept it around after it was passed down when gramps left this world, to occasionally use it for truck stuff and to haul a jeep around to the trails. but I find myself just hopping in and driving quite a lot more than I figured I would.
2010 (4.8 so VVT only) with 202k on it as described- though broken AC. Guy near me in western NY fixes frames and based on his Facebook page he does about 2-3 GMT800s a week. Frames rot out around the gas tank or the front suspension. A buddy of mine had roughly 30” of frame fixed or replaced on his 2013. Trucks totally fine otherwise, just design flaws and undersized drain holes trap water inside the frame.
I have seen a couple with the tubular cross bar just in front of the gas tank completely rusted through at the frame rail. I don’t see it on mine, but yeah, weird design flaws.
My younger sibling had almost the same 4runner (V8) but was maybe a year or two older, and it was white.
My father said that the mechanic said the frame was so bad it wasn’t safe to drive… I was (mostly) surprised to hear this, but was aware of Toyota frame rot issues.
I climbed underneath and it looked almost identical to the pictures you have above, I could easily push my finger through several places in the frame box section.
….and it only had about 130,000 miles on it. Everything worked, and we loved how that thing would drive (that torsen center diff in all of these was truely the best).
It lived its entire life in the northeast (NJ, NY, and MA). We think the proximity to the ocean + winter roads vastly accelerated its demise…
frame swap it is! Easy, right? /s
Haha
Normally, I come running to Toyota’s defense, and this will be partially true today…
“Any of my Jeeps equipped with the unkillable and truly reliable 4.0-liter straight six bolted up to an Aisin AX-15 manual will run and drive longer than these Toyotas…”
Yeah, no.
Sure the 2UZ requires the occasional Timing Belt, and they are interference engines, but you don’t often hear of Wranglers and Cherokees lasting as long as Toyotas (there are several documented million-mile 2UZ engines out there). Sure the 4.0 is fairly reliable and simple, but the stuff bolted to the engine will fail long before anything from Toyota (water pumps, oil pumps, any gasket/seal). Let’s not forget that the transfer case behind many 4.0’s will explode if you don’t do the slip yoke eliminator. Chrysler products will never be as stout long-term as the Toyota equivalent except…
Yup, the frames on these 4runners (and pretty much all body on frame Toyotas) are awful in wintery-salted road states. A buddy of mine had a really nice 4th gen 4runner (like the one above), until I looked underneath. Not as bad as your example, but it was still the worst brake job of my life (for this desert-born dude). That being said, let’s not pretend that TJ Wrangler frames are much better.
The interval on the 2UZ-FE from toyota is 9 years/90,000 miles to boot. The one on my 03 GX wasn’t changed by the original owners until 2017 at 135k miles. While I’d absolutely never go that long, and am due in about a year on time, but far from it on miles. Meanwhile there are VWs and Audis with timing chain guides that have shorter lifespans, and several BMWs with Rod Bearings that are more consumable than that. While yes its invasive and a pain, every decade and nearly 100k miles is a pretty lax interval.
At least T-Belts are relatively serviceable, versus many timing chains. I lose sleep at night thinking of the timing chains on many Audis that require an engine out.
Thank you, I was coming to say the same thing.
We all have our blind spots and the 4.0 seems to be DT’s. It’s no doubt reliable for the time it was designed, but that doesn’t mean it’s reliable in the million mile sense.
I get it, saying a Jeep can outlast a Toyota is gonna get me some guff, but I’m an engineer. I’m tellin’ you like I see it based on the hardware/service needed on both engines. The 4.0 doesn’t have an obvious weakness. It’s sometimes put in vehicles with undersized cooling systems (like the XJ), but when put into a vehicle like a ZJ, well, just look at it.
They truly are as reliable if not more reliable than a 2UZ-FE. You don’t have to tear the engine apart every 90,000 miles, which is a big deal.
Not to relitigate the other post, but to me this is not relevant to the question of which engine is more reliable. It matters to the cost of ownership, but not to the ultimate expected life of the engine.
How much maintenance/repair you have to do to an engine is a key part of what makes it reliable, but again, that’s gonna take us down the rabbit hole of the old post.
Having just replaced broken timing chain tensioners on a Jeep for a friend (I would never own one), which was way worse than doing a timing belt, I really don’t understand the argument at all.
There’s nothing not to understand; you and I are in agreement that a badly-designed timing chain engine is worse than a timing belt engine.
We are simply using the word differently then.
Even so, I would bet real money on a Toyota V8 costing less than an AMC 4.0 to run for 500,000 or 1,000,000 miles.
I’d definitely take that bet.
Well there unfortunately isn’t any way to know for sure, but the stories about million mile Tundras with no engine rebuilds seem to be everywhere, while I can’t find even a single Jeep at a million.
Maybe a goal for one of your Jeeps?
Nope, count me out. Jeeps rarely make it to 1 million miles for a reason, and even though it’s not the 4.0 or the drivetrain, it’s pretty much everything else.
They are simply not designed for the job.
There could be million mile Tundras that HAD rebuilds also and their owners may not be on social media to explain it…and there is zero guarantee that Toyota owners ALWAYS can be trusted to say the truth.
There can also be million mile 5.3 and 6.2 AFM/DFM engines intact with their original transmission used for hard work, but not a SINGLE owner comes forth and says I have one and its great etc etc and is interviewed by the media…because they do NOT need to , or they keep driving it….
THIS ALSO DOES NOT mean the engine is a failure either(even with its known problems), Toyota owners need self-validation, which is something that ANNOYS me to no end).
I’d rather change the starter on the 4.0 though.
I’d rather do the Toyota 4.7 starter over a 5.7 starter. That is 7 hours I will never get back.
Add in labor, and you’re spot on. Sure the Toyota will require maintenance and parts, but it won’t nickel and dime you to death.
With age, they will nickel and dime you to death for sure, like any other car does. Not everyone will admit it. Now…try to prove me wrong…
And it feels like it’s worth noting that the standard engine in this gen of 4Runner was a chain-driven 4.0L V6 which the majority (along with other Toyotas) were powered by, not unlike the Jeep 4.0 powering the majority of its offerings for years. At this point the Toyota 4.0 has been in production longer than the Jeep 4.0 I6 too.
None of that is a knock to the Jeep motor, and the Toyota 4.0 was never known for its character really; I get that the V8 is the subject of this 4Runner and the past Land Cruiser/LX experience but it’s not like it’s the only motor that carries the rep for Toyota.
David. I mean this without shade, since I like what you do.
You need to understand that there is a difference between what an engineer wants, what is produced, and how the end user treats the product.
I feel very strongly that if you were getting paid to work on loads of engines at a dealer or indy shop, and you worked on a 50/50 ratio of timing chain equipped OHC engines and timing belt equipped engines… you might not hate timing belts so much.
Disagree with me all you want. But I hated a lot more timing chain equipped OHC engines for their timing system vs. belt driven ones when I had to service it.
But I think that we can both agree on one thing…”wet” belt systems are probably the worst of all types.
I don’t disagree with you. Of the two — poorly designed timing-chain engines and timing belt engines — I’m going to hate poorly designed timing-chain engines more.
David, I feel pretty badly about you having the 4.0 questioned, whether it is its application or its engineering, since I know you love them.
I do have to ask: How many have you had fail for running lean during your time as a blogger?
Anecdotally, I know several people that have had lean problems with them. By problems, I mean failure.
Couldn’t we argue that putting the AIT in the manifold causes lean conditions due to heat soak? Jeep admitted it when they finally moved the AIT probe upstream in ’06 ish, just a few years before the engine stopped being made. That, to me, is an engineering failure.
Maybe there is data that says otherwise, but I think their best value is in how easy they are to replace.
Zero. I’ve never had that issue on the 13 straight-six motors I’ve owned.
The biggest issue with the 4.0 is that it was put in the XJ, which was designed for much less powerful engines with less heat-rejection. The result is that the XJ’s cooling system is just marginal. Any amount of contamination in it and you could pop that head gasket like I’ve done a few times. (Not an issue in the ZJ, hence why I’m such a fan).
I stand corrected. I thought I read something about a heat stress riser in one of yours that couldn’t be machined out, but I guess it was a motor you had bought, not run.
I will press the issue no more. I genuinely hope you get to enjoy these for a long time.
Hmm. I wonder which engine that was… Maybe my FC engine?
Anyway, they’re not perfect engines, I’ll readily admit. But you get a lot out of them if you can just keep them cool. (I’ve cracked multiple heads in my day from overheating!).
There were multiple issues that occurred with the Golden Eagle’s head over the years. That may be what you are thinking of.
That was the AMC 360. I hate that engine.
It’s just really weird how you ignore the chronic and very common issues the 4.0 Jeep has. If you ignore all of the cracked piston skirts, cracked cylinder heads, exhaust valve carbon build up issues (due to valvetrain issues preventing valve rotation), hard starting from injector overheating, cracked exhaust manifolds and crank position sensor issues the 4.0s have – it’s a perfect engine! It’s not like I’m making this stuff up either. Everything I’ve mentioned is all over the internet as very common Jeep 4.0 issues.
The amount of rattly late-model 4.0s I still see driving around that have obvious piston skirt failure is insane. I would put money on that almost every ’99+ Jeep 4.0 with 200k+ miles has at least one cracked piston whether the owner knows it or not. They will run for a long time with cracked pistons – often time it only manifests itself as the engine sounding a bit rattly on cold start. Most owners will chalk it up to lifters or piston slap, but it’s almost always cracked pistons.
For me, and my car friend group personally: We’ve changed out late model 4.0s where the cracked pistons finally detonated, we’ve dealt with 4.0s that misfired at idle because of carbon’d up valves, we’ve crawled under XJs in the snow with 5 feet of extensions to change a crank position sensor. We’ve dealt with countless cracked exhaust manifolds.
The Jeep guys just like to say “Well there were a few bad years”, and then give you give you a list of years and common issues that essentially spans from ’96-’06
On the other hand, there is no such list of issues for the 2UZ. There are no “bad years” of 2UZ. There are no “bad head castings prone to cracking”, there are no “valve rotation” issues, there is no risk of a piston skirt cracking.I’ll GLADLY deal with changing a cheap belt and two idler pulleys every 100k over dealing with cracked heads and pistons.
There is a reason why the 2UZ has the reputation it does.
These just aren’t issues on the vast majority of straight six engines. The AMC inline sixes I’ve owned are between 1976 and 1996, and these engines are truly flawless. No piston skirt issues, no head issues unless overheated. And I don’t have to tear the motor apart every 7 years. They just run with minimal maintenance.
Consider when AMC straight sixes entered production, and you basically have 40 years of flawless straight sixes, followed by a few issues here and there on 99-2006 motors – issues that tend to present themselves at 200,000 miles.
So, you’re definitely stretching a bit, but again, anytime anyone says an American engine can outlast a Japanese one, they’re gonna get some pushback. So I was expecting it!
Now you’re redefining the parameters.
You said, specifically, “Jeep 4.0 + AX15″. That engine was in production from ’86 to ’06. You can’t just hand-wave away literally HALF of its production run and say “those years don’t count!”
Crank sensors, cylinder heads, valves, piston skirts, exhaust manifolds, injectors overheating, cam sensor/OPDA failures (infamous “laughing monkeys” and stripped out drive gear). Most of these issues present themselves well before 200k as well. A lot of 05/06 TJ guys keep a spare OPDA on the shelf unless they upgraded to the aftermarket one.
Once again, the 2UZ had no such issues throughout its entire production run and neither do the 1UZ/3UZ variants. The entire Lexus brand was riding on the UZ engines being reliable. The UZ + A340 powertrain is basically as bullet-proof as it gets. Actually, ironically enough, the A340 (with an AW4 sticker on it) is basically the most reliable part of any ’96+ XJ.
…and it’s hardly “tearing the motor apart” to do a timing belt. You literally remove 2 brackets, a few plastic covers and everything is right there. The majority of the labor doing a timing belt on these vehicles is getting the truck itself out of the way of the engine – but that’s not the engine’s fault.
I can tell you for a fact that it takes just over an hour to do a timing belt on a 1UZ in a Jeep application 😉
Maybe 99+ AMC straight six engines have piston cracking issues, but 1963-1996(33 years if you’re counting) motors rarely do. I have never experienced one in my six AMC straight six engines. Same goes for cracked heads.
It also seems that you are overestimating the prevalence of exhaust manifold and crank position sensor issues. I have a 230k mile Cherokee that’s running a factory crank position sensor and a factory manifold. I had to replace both on another Cherokee I owned. I also had to replace both of those things on a 2008 Grand Caravan I owned, because those are normal failures for a high mileage car to have.
I have never even heard of the injector overheating issue you’re talking about, all I know is that all my Jeeps have super crusty 30 year old factory injectors and they run great.
The injector overheating issue caused hot starting problems. There were multiple TSBs and attempts to fix the issue. Usually involved a dealer installing extra insulation around the injectors.
Yet there are 2UZs that blew up even though they were perfectly maintained. And, the 5.3 LM7 of that time was the ONLY motor that came close to the 2UZ…also. And, not everyone can pay for a 2UZ truck or SUV.
Now, let us see if the twin turbo V6 TT is AS simple to fix as the 2UZ is.
It’s not a blind spot, the 4.0 really is incredibly reliable and really can go a million miles. Not just for the time is was designed(which was the mid sixties btw), but for all of time.
Slip yokes are totally fine! Sure, you’ll be doing water pumps here and there, but you don’t have to do timing belts, and besides an occasional water pump, the whole powertrain and drivetrain will never fail you. It’ll leak, sure, but fail? Nope. Few things are more solid than 4.0-AX15-NP231-Chrysler 8.25 rear axle. None of them has an obvious failure point if you just swap the fluids and do an occasional accessory item.
Rest of the vehicle (like interior plastics and paint)? That’s a different story.
Early 2UZs without VVT are not interference, which helps a little.
Even the VVT ones are partial interference engines, from what I understand. Depends what stage the VVT is when the belt fails on whether you need valves or not.
Right, that’s what I’ve heard too.
I don’t know what transfer case you are talking about, but the most common NP231 is famous for being strong and reliable and long-lasting and NOT exploding if you don’t do a slip yoke eliminator.
Personally, I will take an SBC 5.7 over a 4.0 Wrangler I6. Sure, they have their own problems like the optispark (just like the 4.7 2UZ has the timing belt…and starter UNDERNEATH the manifold), but a C/K 1500 4WD w/5.7 at least does not have the “female” stereotype that a Wrangler with the 4.0 I6 has.
The same thing happened with my Saturn VUE. The J35 under the hood ran beautifully, the transmission was smooth, the interior held up well, and the body panels looked great (though tbf some of them were plastic).
However, the structure turned into a horror show and the car had to be decommissioned.
Corvettes and aluminum F-150s would like to have a word.
I will say, as a former truck salesman, getting undercoating done on any vehicle that will live in the midwest/anywhere with salt (oceans/roads) is SUPER effective. I just bought a 2016 Sierra and the old-timer that owned it before me had it undercoated. Sucker is MINT underneath after 8 Minnesota winters. It just works. I’ve crawled around under 8 year old MN vehicles and they are usually trashed by then.
I think a lot of 2015 era F150 buyers didn’t bother with any rust proofing because the dealer sold them on the idea that the truck ‘can’t rust’…
Definitely worth the effort to spray the frame.
Ziebart is still a thing for a reason.
I’m in Minnesota and this is the first year I picked up a bunch of Fluid Film to try to DIY some protection. Applying it is kind of gross, and it stinks, but I’m hoping it prevents anything too horrendous from growing under there.
It’s worth whatever it costs, and it’s not that much! Krown is my go-to.
Considering that K2 trucks are also prone to rust when BADLY maintained…what you got was VERY impressive. Keep up the maintenance and it will last….
Avantis have a similar thing going on, thanks to their fiberglass bodies, but those hog troughs rust out like it’s their job. And people still want top dollar for minty looking ones, perhaps assuming that all buyers are somehow physically unable to crouch down and look underneath
There was even a guy on Cars and Bids who got his auction cancelled and account banned because he blatantly spray painted the frame of his FJ Cruiser before taking pictures. Believe he even had the rust oleum cap in one of the pictures. Here’s the auction, check picture 87, and that car didn’t even have 200k on the clock – https://carsandbids.com/auctions/rwyEyvNw/2007-toyota-fj-cruiser
Yeah, FJ’s are pretty bad about that. The truth serum for those is how clean the rear diff looks.
No friggin’ way I am ever buying another used car from the Great Lakes Salt Paradise. I’ll spring for a couple of hotel nights in Memphis or Nashville and find something that hasn’t been blasted with a Klingon disruptor.
My GX did the same thing, but eventually, had to sell it while it still had some value.
I snagged a 2017 GX and will be doing undercoating this year. Already I had to address the welding seams all the places where I put on sliders. Toyota frame seams are apocalyptically bad, but some off road accessories are so much worse.
I’ve got an 03 GX 470, and while mine was clearly garage kept for most of it’s life and has a nearly immaculate undercarriage, I intend on getting it treated soon. I want to do some light to medium off-roading, and want some puddle protection.
My 470 was an 04′ and had some frame treatment done at some point, which left it in very good shape: even an independent inspection was impressed.
But that coating wore off, and where I live, they use fracking brine (or, plain brine) in some places, so it just kills stuff. The rear crossmember was pretty rough, though still would pass inspection that year. There would be no second year.
So I found a 460 in the south with no accidents and dove back in. Did I say no accidents? I meant no reported accidents. Front crash bar was sommmmething, but I swapped it out for a bumper anyway. Nonetheless, it was a good swap and been a great rig.
That does unfortunately seem to be what kills many GXs. Mine was a one owner suburban Maryland car from new until 2017 according to the Lexus website service history, and had one minor “incident” on the Carfax which appears to have been a minor deer strike given the hood, fog lamp lenses and grill appear original, but has one new headlight on it.
Having lives most of it’s life in a salt-free county and being garage kept no doubt saved it from a much worse fait. Too dang nice of a vehicle to risk trashing due to being reckless now.
When the underbody pictures appeared, I heard the Psycho shower theme in my head.
Did they make you feel stabby?
It occurred to me that I am overdue for a tetanus booster.
I heard it too, and I had visions of someone going all stabby with a screwdriver.
My sphincter tightened considerably and did not relax to nearly its normal level until you said he had replaced the brake lines.