Turning an engine 90 degrees for use in a different application usually results in fairly harmless engineering compromises. It’s why Nissan 350Zs starve their front two cylinders of air, and why you can’t simply use a front-wheel-drive LS4 V8 from a Grand Prix GXP in an old Camaro without some modifications, but neither of these quirks are anywhere near catastrophic. However, notice I wrote “usually”? There’s an exception to every rule, and Ford cars and crossovers equipped with 3.5-liter and 3.7-liter V6s are an exception, because they can be mechanically totalled due to simple water pump failure. Here’s how.
On most cars, the water pump is driven by either the serpentine belt or the timing belt/chain, two arrangements that have their own pros and cons and take slightly different approaches to water pump replacement. In the case of the former, losing a serpentine belt means you also lose drive to the water pump. If this happens, you may notice a 12-volt charging system fault light on the dashboard before the car starts to overheat, or notice heavier hydraulic power steering if your vehicle’s so equipped. Another plus besides these pre-overheat warnings is that if a serpentine belt-driven water pump starts to leak, replacement it is generally fairly easy because it’s bolted to the outside of the engine block. For instance, a 2008 Toyota Camry with the 3.5-liter V6 engine uses this arrangement, and even though you need to pull an engine mount to change the water pump, book labor time comes in at a reasonable 4.2 hours.
In the case of a vehicle with a water pump driven by the timing belt, that belt will have a fixed replacement interval and the water pump almost always gets changed with the belt as part of a preventative maintenance regimen. The 2008 Honda Accord V6 uses this arrangement, has a timing belt interval of 100,000 miles, and the whole job requires just four hours of book labor. Not too bad for a timing system-driven pump swap.
Screenshot: YouTube/C.L.S. All-In-OneHowever, then we get to Ford’s transversely mounted 3.5 liter and 3.7-liter Cyclone V6. While timing chains from non-German manufacturers are generally maintenance-free for the life of the vehicle, Ford went with an internal water pump design, i.e. the water pump is driven by the timing system like on the aforementioned Accord (except a chain instead of a belt).
This wouldn’t be a huge problem if water pumps lasted forever, but they don’t. Seals can age out causing leaks, water pump drive bearings can wear out, and plastic vanes on the water pump impeller can break. I’m not going to clown on plastic water pump vanes, as bits of plastic in cooling passageways sound less bad than having bearings in a metal impeller pump go bad, leading to the vanes chewing up their cavity and sending bits of metal everywhere, but I am going to highlight why Ford’s specific design has some serious flaws.
Firstly, access to the pump takes a while if you need to change it, as this extremely helpful DIY video from YouTube channel C.L.S. All-In-One shows. On an all-wheel-drive 2011 Ford Flex with the naturally aspirated 3.5-liter V6 engine, water pump replacement calls for 10.8 hours of book labor. 10.8!
Assuming a relatively inexpensive labor rate of $120 an hour at an independent shop, that’s definitely more than a grand in labor alone. Turbocharged models are even worse, with a 2011 Flex Ecoboost water pump replacement calling for 12.3 hours of labor. However, that’s assuming a water pump suffered from vane failure or if a water pump leaks caught early enough from the tiny weep hole to not cause further damage. There’s another failure mode that could be much worse.
Remember those seals we talked about earlier? Well, because the water pump on a transversely mounted Cyclone V6 is driven by the timing chain, on the other side of a series of seals and bearings from the coolant sits an oil-lubricated cavity for the timing chain. If you’ve ever seen the results of an internally blown head gasket, you can probably see where this is going.
Should the seals fail and an owner keeps topping up the coolant instead of dealing with the problem, coolant can mix with the engine oil, potentially resulting in engine damage due to compromised lubrication. In the event this happens, and it certainly has to owners, the most sensible path forward is replacing the entire engine with a good used unit. This Ford Edge owner’s story runs along those lines, stating that “I ended up having the entire motor replaced” due to coolant mixing with oil.
Taking a look at complaints owners have made to NHTSA, it seems that this worst-case scenario can get seriously expensive, and it certainly isn’t a fluke event. This 2010 Flex owner was quoted $5,000 for engine replacement, and that seems to be on the medium end of things. Some owners claim to have been quoted upward of $7,000 for engine replacement due to water pump failure, and even in today’s market, that’s entire used car money.
If you have a 2011-2019 Ford Explorer, 2007-2018 Ford Edge, Ford Flex, Ford Taurus X, 2008-2019 Ford Taurus, 2010-2012 Ford Fusion Sport, 2007-2016 Lincoln MKZ, 2007-2018 Lincoln MKX, Lincoln MKT, Lincoln MKS, 2017-2020 Lincoln Continental, 2008-2009 Mercury Sable, 2009-2013 Mazda 6, or 2007-2015 Mazda CX-9 with one of these engines, water pump replacement could be in your future.
With older and especially high-mileage models, chances are it isn’t worth much if it’s knocking on the door of 15 years old. It’s no secret that depreciation happens, but as cars reach that well-used point, a big repair can sometimes cost more than half of the vehicle’s value.
For instance, assuming $1,296 in labor, a list price of $152.91 for an OEM water pump, fresh coolant to top up the system, and a few miscellaneous shop supplies like RTV gasket maker to reseal the timing cover, this repair will end up hitting the $1,500 mark on the low end if you catch the failure early.
Some owners are reporting repair bills costing more than $2,000 to fix a failed water pump, possibly due to higher labor rates. On a 200,000-mile 2011 Ford Flex that’s worth $3,900 in good condition, that’s a tough pill to swallow for a best-case scenario in which water pump failure is caught early and treated before coolant can mix with the oil.
Lots of Fords with these transversely mounted 3.5-liter and 3.7-liter engines were great vehicles when they were new, and I have a particular soft spot for the Ford Flex. However, I probably wouldn’t recommend a high-mileage car with one of these engines, and if you do find a Flex Ecoboost you want in nice condition, it’s a good idea to keep a few grand around for water pump replacement so you won’t be caught off guard with a crazy repair bill.
Top graphic credit: Ford
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A good friend’s wife had a Ford Flex. Luckily they got an extended warranty on it when buying it new… the water pump let go and it was completely covered (it was a big ordeal and cost $5k I believe). 5000 miles before the warranty was up they dumped it for lowest mileage and cleanest V6 Toyota Highlander they could find. He said he wouldn’t get a new 4-cylinder turbo Highlander after his F150’s eco boost V6 turbo nightmare. He dumped the F150 to grab one of the last 2024 Toyota 4runner models before they were gone.
He claims he will never consider Ford ever again, as he was a ‘ford guy’.
Subaru has entered the chat. Apparently the OP hasn’t heard of the cooling system plague that is the NA EJ25 motors from 1998-2013 and the EZ30 AND EZ36 6-cylinder motors. The EJs are notorious for cooling system issues, namely head gaskets, but they, along with the EZ-series motors suffer terribly from internal WP failures turning your oil into chocolate milk. The EJ motors have a WP driven off a timing belt and is swapped during a timing service at 105k, so its isn’t terrible considering.
The EZ series is worse than the aforementioned Ford 3.5 and 3.7 motors. The WP is run off one of the two mile long timing chains and there are two gaskets for the water pump, an internal o-ring and an internal cover gasket (which is the one that leaks the most). The water pump is submerged in oil behind the front timing cover. Oh and that timing cover requires you remove the radiator, fans, belts, move the accessories out of the way (alternator and power steering pump), and remove 59 bolts all around cover and separate the bolts into the 4 different sizes and types. To replace the gaskets for the water pump, you need to remove the entire timing hardware, guides, chains, gears, oil pump, and the rear cover to the tune of 105 total bolts in 9 different sizes that need to be separated.
Then once you replace the pump and gaskets and reassemble the front of the motor and pray to the Subie gods the RTV didn’t smear on either the inner or outer covers before it was reattached so you don’t leak oil, you need torque the cover bolts in a specific sequence at different specs for each bolt type. The dealer recommends removing the engine to perform this service because of the complexity of doing it in the car. The book time is 18.9 hours for the full service. I used to charge $2500 to do this job, dealer would charge upwards of $3k-4k to do it. I’d rather do a couple Ford water pumps than do any more H6 pumps.
Classic Ford. Great ideas, terrible execution (quality /longevity). Bring on the Chinese cars since these legacy automakers can’t seem to figure it out
Note to self: Never buy a Ford.
Good thing no other makes ever have weird, serious, and expensive issues. Sounds like a solid plan.
Wait until the Highlander’s cam phasers go bad. Cost one of my customers 4 grand to fix.
This very failure took out my husband’s 2014 Explorer … fortunately, the pump failed while he was idling in a parking lot less than a mile from a Ford dealer and not, say, driving outbound on the Eisenhower Expressway.
Better call CarShield before you need a replacement engine – Tell them Vivica A Fox sent you.
In other words send the bill to Vivica A Fox when the aftermarket warranty company refuses to cover the repair.
Ugh, this specific failure has kept me away from a bunch of these cars I otherwise really like.
Explorers and timing chains, a tale as old as time.
The SOHC 4.0 was also notorious for timing chain and tensioner issues but at least the water pump wasn’t chain driven.
The good thing is that these 3.5s and 3.7s can last a long time on the original water pump. I’d just factor in a replacement at 120-150k if I had one of these.
5th gen Explorers are otherwise pretty good and relatively affordable these days, this is one example where preventative maintenance is worth it.
It’s still short-sighted to focus on selling new cars when including a known troubling design element. It is human nature to tell others about bad experiences. If this happened to me I would be telling anyone I met to stay away from Ford products. Some manufacturers don’t seem to make cars, they make market-shrinking devices – GM, Ford, etc. At the same time, people do share great experiences. Many families left the Big 3 years ago and will never be back. Quite a legacy.
I am.sure some engineer said this was a bad idea and was overruled. This happens all the time. Ex: that o-ring will hold up at below freezing temps; don’t worry about loose foam. Three out of five ain’t bad. Participation trophies all around!
The Miata in my photo is actually an example of this, and wouldn’t you know it, the compromise was a cooling system issue.
The 1.8 liter in a 1994-2005 Miata was originally used transversely in other applications. In order to get the weight balance right in a longitudinal application, Mazda shoved it as far back in the engine bay as possible, leaving no space between the rear of the engine and the firewall. The consequence of this was that the coolant could no longer pass directly through one end of the engine to the other, so the two rear cylinders ran hotter than the fronts. No problem with 140 horsepower but …
… once you start adding horsepower or running heavy duty cycles, it can bite you in the butt later down the line. I learned this the hard way. I kept adding horsepower to mine and regularly flogged it in the canyons. Oh I did a lot of reliability mods, like an improved oil pump (stock pumps had teeth that would shatter due to vibration and eat the engine). I also replaced the water pump and timing belt, added an oil pan baffle, an aluminum radiator, etc. When I found out about the uneven cooling issue, I researched coolant reroute kits which had a low profile elbow that restored the coolant flow from one side of the engine to the other. I bought one too, but I was too late.
Right after buying the reroute kit (around 160,000 miles, 30,000 of them mine), it started having difficulty starting and didn’t run right until it was warmed up. Eventually it wouldn’t start at all. A compression test revealed the problem: 120 psi on the cylinder closest to the radiator, getting steadily worse as you want rearward, with the last cylinder reading at maybe 30 psi. The heat had done the rear cylinders in. At this point I had to commit to either rebuild the engine or sell it as a roller. I chose the latter. It already was too modified to pass smog and it wasn’t worth it.
Sold it for $1000 to my mechanic who rebuilt the engine (with the reroute) and sold it to a guy in Texas. I checked the VIN number a few months ago, and apparently someone in Montana bought it and painted it green (it was silver before). Glad to know it’s still out there putting a smile on someone’s face.
Crap like this is just one of the reasons why electric motors are our future. Eh, once they figure out how to put out those lithium fires…
Engineering trade-offs can be a wild game.
Are all the Lincoln Continental engines affected by this? I will be looking at picking one of those up in the next year or two (hopefully the twin turbo) , and this would definitely factor into that decision .
Only the NA V6s are. The turbo ones are a different design and do not suffer from this flaw.
“The turbo ones are a different design and do not suffer from this flaw.”
Yeah they replaced it with a different flaw… wet rubber belt driving the oil pump… at least on some versions of the 2.7L turbo.
Wow very interesting; thanks for pointing that out!
It’s the big V6s with the issue (3.5 + 3.7) the 2.7 is a different design. So if it matters to you, check your specs.
Don’t worry. All good cars (and bad) go to heaven. And Fords keep me very busy in the salvage car biz. And Hyundai. And Kia. And Chevrolet. And…
I see you didn’t mention Nissan and their amazing CVT’s
I see a lot less of them on the salvage market than you would think. Many owners/bhph dealers (many?) fix them as they remain very popular. The Korean makes, not so much.
Haha! I have a 2013 Taurus SHO. Started getting the CEL for a stretched chain at 95k miles. Water pump, chains, phasers, etc. were ~$3500. What a stupid, stupid design.
My work vehicle is a de-copped Exploder PI with the 3.7. Sometimes, I could swear I smell coolant.
I always have this moment where I wonder what happened in the engineering meeting for things like this.
Water pumps fail. Timing chains shouldn’t. Why drive the failure prone element that could fail with the part that should never have to be serviced? Especially since water pumps have a failure mode that could destroy the lubrication system (and the engine)?
I know the answer was cost and packaging. But you think Ford would have learned something from Chrysler’s 2.7L V6 debacle.
They did learn. They learned the cost of failure and selected their preferred failure point based on the fact that it was the most profitable.
This is the same company that made the 1.0 Ecoboost with the wet timing belt, this water pump fiasco is on brand
The engineering meetings are where all the engineers agreed, whether reluctantly or otherwise, this was a bad idea and they’d take it back to Product to confirm we won’t be doing this, as it’s a bad idea.
Engineering’s mistake was admitting it’d save $2.70 per unit in tooling and machining, whereupon Product informed them that’s exactly what they’ll be doing.
Less punchy caveat: I’ve seen some engineers make some goddamn terrible decisions too. I just know that Ford especially has been refusing to step up on quality for a long, long time now.
-Signed, a guy that had to replace a failed plastic coolant tee that connects directly to the block on my F-150.
This is clear to owners and mechanics but is unlikely to be considered by anyone at a corporate level. Doing so isn’t part of any P&L calculation that matters. It was beyond the warranty and car companies sell new cars, not used ones. Never forget that fact and learn to appreciate any longevity that exists as the gift it is—or at least factor it in to your budgeting calculations.
It would be nice to get a repeat customer now and then, though. This EcoBust design has people swearing off Fords forever.
That would seem reasonable, and car companies make some effort to make things that will last 8-9 years without too many issues since people keep their cars for about 8 years on average. However, most people don’t pay enough attention to overall reliability trends to know if they just had bad luck or if it is a systemic issue with the brand. Just look at BMW, which for years had by far the highest cost of ownership due to maintenance issues, yet people who like cars will defend them with lines like “with regular maintenance..” “mine has never given me an issue…”
Part of the calculation is that things like repeat customers that might impact sales 8-10 years down the road carry far less weight than immediate costs. The savings are real and immediate, and the risks are far off, with only a small percentage chance of happening.
Just never forget that the goal of every corporation is to separate as much money from their customers as possible at the lowest possible cost. Nothing else.
Just say no to transverse V6’s 🙁
Had two VQ35’s in our Nissan Quests. Over 260k miles. Transverse is ok, poor design is not. See Nissan CVT before 2018. lol.
The Chrysler 3.6L Pentastar V6 has the same issue in FWD applications.
4 hours for an Accord timing belt??
So, you’re telling me that it’s only 2 hours after you get that $@#%* crank pulley bolt loose?
Volvo inline 5 turbos FTW. You can remove the timing belt without having to remove the crank pulley bolt.
I had to do one on our Volvo wagon plus water pump and I was done in four hours even though it was my first timing belt replacement, went super slow and triple checked everything. Now that I know what I am doing I can get it done in one hour if ever need to do it again.
Nice!
Fastest timing belt(s) I ever did was on an 87 Subaru DOHC. 45 min from hood up to closing hood after starting motor.
While I owned it, I fixed the troublesome Hitatchi carb by tossing it for a Weber—which then necessitated deleting power steering pump (or a wonky throttle linkage). And tossed the AC as well for simplicity. Nothing but an alternator on the front of the motor when I sold it to my sil.
4-5 years later, when she called me & said it ‘sounded funny cranking’, I took both belts and the driver’s side tensioner out there. It’s nice working behind yourself when everything is torqued correctly, anti-seized, etc, no?
>sorta makes up for the weekend of misery after snapping that one stupid water pump bolt
Timely article with the earlier one today asking for 3-row advice.
This precise problem occurred around 180,000 miles on my parents’ Flex and around 190,000 miles on a sibling’s Flex, and is why we no longer have either. Quite upsetting because they’re decent vehicles otherwise.
“Achilles” would be a great name for a car if it weren’t for karma (and car reviews).
For that matter, so would “Karma.” Oh boy.
VW Karma Ghia.
Had the timing belt go out on my wife 2014 Flex Limited EcoBoost engine at 110k miles & thankfully the dealership offered (honestly damn near insisted) to do the water pump at the same time. It wasn’t cheap but it’s been running like a top since & she loves the car so I think it was well worth the money. I appreciated the dealership pushing me on it & it only took a few minutes of googling Ford Flex water pump to know why.
My wife’s younger sister is 16 and just got a 2011 Edge as her first car. 🙁 I *think* the small business they bought it from (that used it as an occasional delivery car) already had the water pump done, though. Fingers crossed, at least.
I have a 2012 Explorer that my son drives that has 235k miles on it, and my brother and I replaced the water pump on it a year ago. It isn’t that it’s hard, it’s just that it takes so long to actually get to it. You may as well plan to change out every wearable part anywhere along the path, because God forbid you have to get back in there again. I would plan a solid two days, and definitely have another car to drive just in case anything goes wrong.