You bought a new hooptie in the summer, and everything was going great. It starts first time, the temperature needle stays in the middle, and it even came with four decent tires. Only, there’s a problem. It’s winter, now, and you’ve noticed the heater’s out. You may have even noticed a dribble of coolant on your floorboard. Your mechanic buddy tells you it’s the heater core. “I’ll fix it myself, how bad could it be?” you say with confidence. Your wrenching friends look back at you with pained expressions, shaking their heads in dismay.
Wrenching on your own car isn’t always bad. It’s often a great way to learn things and save money. Changing your engine oil is an easy enough job, for example. From there, you might step up to more difficult task like replacing your shifter bushings or changing a water pump. Unless you’re an all-out masochist, though, there’s one job you probably want to avoid—swapping out a heater core.
A heater core is not expensive or complex — it’s basically just a small radiator under your dash with an inlet and outlet pipe. And yet, changing one out requires more work and more hassle than almost any other typical job on a modern automobile. Let’s explore why this cursed job is such a monumental pain in the ass.
Heater What Now?
A heater core is the heat exchanger tasked with turning engine heat into cabin heat to warm you and your passengers. Typically, it consists of two end tanks connected by a bunch of straight tubes that have lots of fins attached. Engine coolant flows through one end tank, then through the tubes, giving off heat to the air that passes through the fins, picking up heat to warm up the cabin. (The additional surface area of the fins attached to the tubes help the air pick up heat). In order to get that air through the heater core and into the cabin, a blower fan forces air through the heater core to warm it up and keep you nice and toasty.
Fundamentally, the heater core works exactly the same way as the radiator in the front of the engine bay. The difference is that it’s much smaller, and it’s not intended to actually cool the engine to any major degree (though it can help as a trick if you’re starting to overheat a bit). It’s just using the waste heat in the engine coolant as a convenient way to warm up the interior of your car.
You might like to ignore a busted heater core, but depending on the failure, you might not have much of a choice. If the heater core is leaking, your engine will be losing coolant—potentially quite quickly. If you get too low on coolant, you might end up overheating your engine. What’s worse is that the coolant will most likely be dripping down inside the cabin, underneath the dash and onto the carpet/floor mat. Less troublesome but still far from ideal is when the heater core clogs. Without coolant flowing through it, you don’t get any heat transfer to keep you warm. It’s troublesome, but less likely to pose a risk to your engine and interior.
Since they’re so simple, heater cores are actually pretty cheap, parts wise. They’re just small radiators, after all. You can find them for under $200 for most common models. They typically have one inlet and one outlet, so hooking them up is easy. So what is it that makes this job so hard?
Access Is Everything
The problem with heater cores is that they tend to live in an awful, inaccessible location deep under the dashboard. As a bonus, the inlet and outlet pipes typically feed through the firewall and into the engine bay. They usually end up tucked somewhere off to the side of the engine, buried so deep that you have to pull apart half the car to get to them.
Take a car like the BMW 3 Series—say, the E90 generation. Head over to the Bimmerpost forums, and you’ll find a helpful DIY guide explaining how to do the job. “Please allow for an entire weekend to get this done, even with a helper,” writes zigsman, noting the job took them a full 16 hours of wrenching to complete. Meanwhile, DIY Salvage Guy on YouTube says you can expect to spend 20 hours doing the work, or spend $3,000 to get a shop to do it.
Just reading the tools list, you get an idea of how bad this job can be. Beyond the usual screwdrivers and socket set, you’ll also need a whole set of air conditioner maintenance tools. We’re talking gauges, tanks, fresh refrigerant, the whole shebang. Why? Well, in this case, since the heater core pipes are a particularly inaccessible part of the engine bay, you have to remove parts of the AC system to get to them. This means that purging the air conditioner is just one part of this job, and you have to refill it—accurately!—when you’re finished, too. Recharging the AC is an ugly job for a first-time DIYer, and needing all those extra tools just adds to the cost and frustration of the job.
Other headaches include having to pull apart the steering—and don’t let the wheel rotate, or you’ll wreck the clock spring and add a whole other painful job to your list. Assuming you can tackle all that, you also have to pull apart the entire dashboard to handle the interior side of things, too. Assuming you can disassemble and reassemble everything without destroying any of the fragile plastic parts in the BMW engine bay, you might have a shot at pulling this off. Just don’t forget to have the BMW service software on hand to clear any frustrating codes that pop up when you’re done.
BMWs aren’t exactly known for being easy to work on, but the story is much the same elsewhere. Try swapping a heater core on a Chevy Malibu, as covered by Mississippi Wrenches. You’ll wind up doing the same amount of work. “I usually don’t say a lot of jobs are hard, but take my word on this one here—this job is not for the faint of heart,” says the exhausted wrencher. There’s no getting around it—you’ll need to pull the whole dash to get to where the heater core lives, deep under the dash. In the engine bay, it’s the same story—there’s a bunch of AC lines and other stuff that make it hard to get to the hoses on the hater core. Even when the plastic heater box was pulled out of the car, it had to be drilled in multiple places to pop it open and free the core for replacement.
Replacing a heater core is a lot of work, but it’s also ugly work. Uncomfortable, back-twisting, knuckle-busting work. Compare it to another job, like replacing a head gasket. That can be time consuming, but for most of the job, you’re attacking the engine from above. You’re unbolting things off the top of the engine, pulling the head, and then putting it all back together. Time consuming, but straightforward.
Doing a heater core is much worse. Have you ever had to contort yourself upside down into the footwell of a car to reach bolts under the dash? I promise you, it’s eight times worse than it sounds. Now picture doing that for hours on end as you pull the dash apart, piece by piece.
Meanwhile, unhooking the pipes on the firewall is sure to strip plenty of skin off and leave you raging as you drop your pliers into the depths for the fifteenth time.
Oh, and at the end of this job? You’re left with a bunch of broken plastic fasteners and trims that will never go back together the same way again. Heater cores typically fail on older cars with weaker plastics. You know the kind. Parts that have been baked in the sun for years and crumble if you look at them the wrong way. You’ll be lucky to have only cracked two or three major dashboard components before you’ve even figured out how to get the infotainment system out of the way.
When the customer asks why a 200 dollar heater core costs so much to put in
byu/Pitiful_Celebration inJustrolledintotheshop
Not every car is as bad as the examples above. If you’ve got something simpler, the job can be quicker with less fuss. You’re still likely gonna have to pull a whole dash apart. Older cars tend to have emptier engines bays with easier access, though. That might mean you don’t have to tangle with AC lines or a forest of sensors and wiring. Maybe.
Say you’ve got something like a TJ Jeep Wrangler, for example. Forum users quote prices around $200-ish in parts and 8 to 10 hours labor for getting the job done by an independent shop. If you get a quote for $1,000, that’s not a bad thing—that’s actually pretty good. On an NA Mazda Miata, you can do the job without even pulling the dash, as shown by GearHeads on YouTube. Even better, the coolant lines going to the firewall are really easy to get to, mounted nice and high in the engine bay. You might even get a sub-$1000 quote for a shop to do it, based on reports from owners on Reddit.
[Ed Note: Some vehicles, like old full-size Jeeps, have heater cores mounted to the firewall in the engine bay. These are a godsend:
Look at how easy that would be to replace! You don’t even have to touch the dash! -DT]
An old Chevy Tri-Five might have been a bit easier to swap a heater core on, as this diagram demonstrates. Plenty of room in that engine bay.https://www.youtube.com/watch?v=bFDkCjR1JqM
When it comes to awful heater cores, though, the title goes to the fifth-generation Chevrolet Camaro. Why? Before you can remove the dashboard to get to the core, first you must remove the windscreen! All because of two bolts in the dashboard that sit right at the base of the windshield. I wish I were making this up.
I wouldn’t be honest if I didn’t tell you there is technically a way around it. According to the Camaro5 forums, It just involves hacking away at some bolts with a Dremel cutoff wheel, a prybar, and a good chance of breaking the windscreen if you make a mistake. Still, the official GM instructions call for windshield removal.
heater cores you say? how about one on a 2011 camaro? (and yes the windshield has to be removed to remove the dash)
byu/zackdman inJustrolledintotheshop
Cheating
When a heater core replacement becomes necessary, it can be a killer for an old car. Few people want to invest $1,000 or more in fixing an old beater, after all. If you live in a cold climate and the heater is a must have, you’re out of luck at this point.
However, if you’re willing to forego the heater, a simple trick might save you. If your heater core is leaking coolant under the dash, you can simply choose to bypass it instead. You’ll still need to be able to get at the coolant hoses in the engine bay, but you won’t have to mess around with the dashboard at all.
This technique is called “bypassing” the heater core, or “looping the lines.” Basically, all you do is you disconnect the inlet and outlet hoses that go to the heater core. You then connect them to each other with a small U-pipe or other fitting. Alternatively, you remove the original hoses, and run a single new hoes from the heater supply port on the engine back to the return port. Either way, instead of the coolant flowing into the heater core and back out, you bypass it entirely. Generally, this won’t cause any harm and can keep your car running and roadworthy when it would otherwise have a serious coolant leak.
This fix is essentially free and it’s also not very time consuming. It also minimizes the chance of you breaking twelve other things on your car while you’re wrestling to free a filthy, leaking heater core.
Bad Times
Some automotive repair jobs are difficult because they require specialized knowledge or tools. Heater core replacement is difficult because it requires a ton of annoying intermediate steps just to get access to the part you actually want to work on. The more parts you touch on a job, the more likely you are to break something along the way, too.
Heater core replacement is perhaps the one wrenching job where it’s not cool to ask your buddies to come round and help. Friends don’t put friends through that kind of pain, even though a second pair of hands is extremely helpful. If your car has a busted heater core and you want it gone, I understand you. If your car has a busted heater core and you’re going to pay someone else to fix it, I understand you. If you choose to just wreck it instead, I get it, I do. Whatever happened, get yourself a cold beverage and try and put it behind you. Heater cores just suck.
Image credits: Lewin Day, Chris Vaughn via YouTube screenshot, Mississippi Wrenches via YouTube screenshot, DIY Salvage Guy via YouTube screenshot, eBay, Amazon, brosolution via YouTube screenshot, Chevrolet, Amazon
The heater core in my 1998 Jeep XJ was bypassed due to a leak when I used it to pick my (now) wife up for our first date, and I had to apologize for how cold it was on that January day.
A few months later, her and I pulled the front seats and the dash and replaced it ourselves, over a couple of days. 9 years later it’s still going strong.
When the heater core in her 1997 Jeep XJ failed a couple of years later, I nervously asked our local Jeep specialist how much he’d want to replace it. The answer was £300! I’ve no idea how he did it for that price, but it worked perfectly and I still haven’t found so much as a misplaced screw.
I decided not to ask why it was so cheap, but I was very thankful!
On a Leyland P76 the heater box assembly had to be removed to replace a heater core. A whole section of the firewall was part of the heater box, and the box was installed from the engine bay side. First step of the job would therefore be engine and transmission out! Luckily I never had problems with any of mine!
“that make it hard to get to the hoses on the hater core”
Hater core. Best Freudian slip.
ha! legit.
In Maine, a “beater with a heater” (and a fresh inspection sticker for the season) is a good deal. The ones listed as “no heat/AC” are a hard pass. I’ve passed up $400 cars that had no heat.
God I love that my M35A2 the entire heater assembly is in the engine bay. That being said due to lack of insulation the floor pan serves as a heater hah.
I had to swap the heater core in my ’95 S-10 and it wasn’t really that bad at all. Of course, my S-10 was a base LS regular-cab with a 5-speed and no A/C
.
I remember removing all the bolts around the dash, then lowering the steering column and just tipping the dash forward towards the seat. There was one bolt on the heater core cover that wouldn’t go back in, but it didn’t seem to matter.
The heater core cost me less than $30, but that was 10 years ago. I started the swap after work one evening, and had column down, the dash tipped down, and the old heater core out before dinner. I waited until morning to put it all back together, but the whole process took less than 6 hours total and less than $50 total including antifreeze.
The moral: Buy an inexpensive, manual-transmission, American-made pickup and maintenance should be less expensive.
“hater core”
You subliminally got it right…they should just change the name to this.
Also, yeah can’t have a “beater w/ a heater” w/o the heater part. Well, I guess you can since I have done it before years ago up north and just wore layers. Even tried one of those $10 plug in ceramic heaters and it hardly did anything of course
I’ve never had a leaking heater core be polite enough to just leave a little puddle on the floor. It’s more like all the sudden your windows fog up and will not clear and you’re just kind of screwed. And with everything you’ve said about how difficult the job is, on a bullnose Ford pickup it’s a 15-minute job. One of the few things a Ford engineer ever did right.
And parts for that job are not expensive. Remove hoses, remove glove box and 6-8 screws. I am sure it was some sort of a peace offering for how hard it is to replace valve cover gaskets…….
Instead of bypassing what would happen if you just put a heater core in the engine bay? I’m guessing it wouldn’t work as well, but should be better than the bypass.Never mind, that wouldn’t help get warm air into the heater system.
Because an engineer will walk past 40 virgins to fuck a mechanic.
> stuff that make it hard to get to the hoses on the *hater* core
Typo, or Freudian slip?
I’ve heard it said about more than one car that it’s built by hanging the heater core in mid air and adding the rest of the car around it
When I was a kid in the ’90’s I bought a 70’s Chevy K10 that had the heater core bypassed. It’s probably a cakewalk compared to most modern cars, but even on that truck the relacing the core was something of a PITA compared to everything else I did on it.
The NA Miata had a lot of issues with the heater core connections getting damaged easily. A common upgrade is to swap to one from a NB which is made of much sturdier material. If you’re crafty and flexible enough it can even be swapped without removing the dash.
Since the heater core is clogged on my 1999 XJ (and to replace it is a PITA) I’m thinking about running the heater hoses to the AC evaporator instead. The AC system is already toast – the PO replaced the compressor with an idler pulley. I don’t see why this wouldn’t work for heat… unless the evaporator also leaks. The tubing going in and out of the evaporator is somewhat smaller than the heater core but it should have some flow. I’m assuming I’ll be able to direct the warm air to where I need it with the controls. Thoughts?
dont let the forums scare you. an XJ can be done in 4 hours. I lower the steering column, and leave the dash hanging on bungie cords – it doesn’t have to come all of the way out.
Far better than using the evap core that is more meant for gas than thicker liquid coolant.
Years ago, I had a TR7 convertible that had a heater core spring a leak. It is not only a soul-draining job to take apart, with all the brittle plastics in the cabin, but Triumph used two pipes inserted with rubber seals into the core. The pipes and seals are unobtainium, so as I mostly drove the car in summer on nice days, the heater core got bypassed.
while no one now is likely to be using an early 60s ride as their winter rat, i did back in 1980s. bought my first car- 63 ford galaxie in 1984. then saw another rougher one- 2door & automatic trans vs my 4d hardtop. for sale on my employers bulletin boards. bought that to drive in salt. it had issues. 1 being – v little heat. but my dad had a 63 ford wagon version of the galaxie abandoned in his back yard. & on those cars, the core was easy to pull. did they consult with colin chapman & simplify? cuz, pulling it out was easy from the vast interior. heater unit was a big black fibered plastic thing not buried under decorative trim . right there below the metal dash. . unbolt from the firewall working inside -under dash & everything was right there. with replacement in hand, visited a friend with garage & heat stove inside. on a cold night, we did that winter rat’s remove clogged core & install harvested replacement core in an evening. even being amateurs & well hampered by Jim Beam lubricant. didnt leak. and heat worked. even better, we didnt run out of cuss words.
The first one I did was on a 1972 BMW 2002 and it took a couple of hours. The next one I did was on a 1982 Toyota Supra and it took up a Saturday. The third would have been a 2003 Mazda3 but I passed when I saw what had to be taken apart. Just did a bypass as noted in the article. On many of the pre 1980 cars you would often see a shutoff valve installed by a previous owner on the inlet hose to the heater core since it was just an offline of the cooling system not a part of the recirculation loop.
Not having heating in a car in Europe and N America in winter is an eye-opener. It very quickly gets uncomfortably cold, even if you dress like Michelin man.
Suddenly all those histories about people not moving in winter in the days of horse and waggon make sense, even having a brasier in the wagon would not help much, as well as being dangerous…
They all have their ups and downsides with heater cores….but Ford is the worst offender in MOST cases…mess of wires you need to get past.
I tried to do the heater core on my 1990 Thunderbird, but I gave up and had to bypass it. There was no chance I was going to be able to do it.
I see. Most cars do require dash removal to access it, but in the Malibu and the Northstar, I wil admit unless you are experienced it IS A PAIN due to design unlike a pushrod GMT800 or a 3.8 V6 (yes, that had its issues as well) to access the heater core. Again, experience matters for all, but this is a general statement.
I replaced the heater core on my dad’s 1982 Buick Skylark. I was younger so I got to lay on my back in the passenger footwell, hair in the coolant that was in the carpet. But I was able to get to it and replace it without a ton of effort. Certainly didn’t have to remove the dashboard like some of these new car photos. Few scraped knuckles and some cursing and we got it done. I would never consider tackling this job now on a newer car after seeing how involved it has become.
This line made my stomach clench. Literal physical reaction that I’m still feeling.
Yes I have done this. Yes I thought about just setting the car on fire. No, insurance of course wouldn’t have covered anything, but a cleansing fire would have solved the problem of me curled up in the footwell on the driver side cursing and asking why someone had decided to place a bolt there and why was it recessed so far???
This is the one job my mechanic flat-out told me not to get done, as it would be an expensive ordeal on labour costs alone, all for a heater core that famously didn’t even provide that much heating when fully functional. And it’s not like there’s an AC unit in a Renault 4 to make things harder; it’s just a time-consuming job on parts that are hard to access. Since mine is clogged and not leaking, I’m fine with not fixing it (it doesn’t really get impossibly cold here in southern Europe). I knew there and then this must be a very demanding job, as mechanics normally don’t advise against something that makes them money.
It is highly dependent on the vehicle.
Easiest heater core ever was the early Fox bodies.
Full instructions:
20 minutes plus warm up and burp time.
Many modern cars are assembled with a fully assembled dash that doesn’t take that much time to remove, if done correctly. However on many of those “dash out” vehicles you don’t actually have to remove the dash, just pull it back on the passenger side. The key is to loosen, not remove the main bolt/nut on the driver’s side.
That reminds me of a job I did several years ago. The Dakota came in on the hook from a customer who had started the job himself and tore the entire dash apart and all sorts of pieces and a ton of fasteners were on the floor only couple of which actually needed to be touched. The customer was not happy that the time to do it was now more than the “too high” price he was quoted that made him attempt to do it himself. I spent an hour or so putting everything he spent 3 hours taking apart, before starting on the actual stuff that needed to come out.
90s Ford probably were not that hard to work on. Now? Things have changed…
Well I was talking about late 70’s and early 80’s Foxes, not 90’s. Modern Fords are on the easier side of things. The dash was installed at the factory fully assembled and it comes out quick and easy as they always include an antenna disconnect in the vicinity of the other passenger side harness connectors. Plus as I mentioned you usually don’t have to actually pull the dash you just pull back the passenger side and leave pretty much everything on the driver’s side still connected.
What about other mechanical bits? Modern Fords keep changing their design…I hear that they are hard to work on compared to let us say, a pushrod engine…
Cost for repair is also much higher according to repairpal…
Same procedure on a bullnose pickup. Changed the heater core in my 88 f250 in a parking garage after work with a pair of vise grips. Took 20 minutes.
80-97 Trucks were much simpler…I do like them….
Man, I don’t get this line of thinking. Stuff like that is exactly what friends are for. I’ve done a couple of two-day PITA heater core swaps (and driven for an embarrassingly long time with a bypass hose in place, more than once), and I know it’s a rough and infuriating job. But if a buddy asked me to help, I’d be honored to volunteer.
Then again, I’m also more than happy to help friends move or give them a ride to or from the airport, two other things that are apparently Too Big An Ask for the modern generations. It’s a bummer. My friends and I did this kind of stuff for each other all the time, and I still will.
Heater and AC repairs are a bitch! You don’t want something dripping in the nether regions of your car.
I have learned through experience that if something on the AC side needs replacing, just replace everything at one time. Otherwise you’ll be back replacing the compressor/evaporator/whatever you didn’t replace the first time.