How to check heater core?

[billygoat777]

Any write ups anywhere? Whats the easiest way to do this? and what else should I check for? I'm smelling coolant inside the car usually when I use the heater.

[zubbie]

The only way to "check" is to eliminate all other possibilities. Check for coolant leaks in the engine compartment, heater valves and then look for wet carpet. You may not find anything so you are left with the 4 hour task of carefully dissembling the lower center console.

[Binjammin]

Look under the car for the heater core drains. They're molded rubber, and just behind the bottom of the firewall. See if there's any coolant dripping from them.

[Mark185]

The heater core in my 89 535i had a small leak for over a year that never resulted in visible drips from the core area. It always smelled faintly when I turned the heat on and I had a constant small loss of anti-freeze over time. There were no visible leaks in the engine bay. I did not see signs of major drippage from the drains Binjammin refers to in his post but the drains were damp.

I had to finally tear apart the dash and heater core assembly to find the problem. In my case, there were O rings between the inlet and outlet connections to the core that were leaking. I had purchased a new core prior to the tear down so I did not have to keep the car apart longer than necessary but did not actually have to replace the core. This was one of the biggest PITA jobs I have ever attempted in 30+ years of turning wrenches. Plan for at least 10 hours of labor unless you have done this before. I could do it now in 3-4 hours but the first time is a bitch.

There is a write up on a web site by a guy named Gale. It is for E32 but the heater core job is the same. I forget the URL. You should be able to find with a web search. It was very helpful.

[billygoat777]

Alright guys, so my AC drain has coolant coming from it, and my coolant is going down a little faster now. I was talking to my friends dad about it who works at a chevy dealer and he said to take the in/out hoses out from the engine side of the firewall and just plug the thing, what would that do?


Does anybody want to help a fellow e34er do a DIY, or does anybody know booktime for this job at an indy shop?

[Binjammin]

Replace the heater core. Bypassing it is so ghetto.

[tka1]

This was one of the biggest PITA jobs I have ever attempted in 30+ years of turning wrenches. Plan for at least 10 hours of labor unless you have done this before. I could do it now in 3-4 hours but the first time is a bitch.


I did a heater core and and A/C coil in a couple of different cars. It's so true. If you ever have to do it a second time, it will take about 1/3 the time.

What really pissed me off was the A/C coil. I replaced it, evacuated and recharged the system and it was great. No more leak. I totalled the car a month later.

[billygoat777]

Replace the heater core. Bypassing it is so ghetto.


Does bypassing it mean there is no heat?

[Binjammin]

Does bypassing it mean there is no heat?

That's exactly what it means. Stop taking your car to whoever told you that was a good idea, except perhaps to run over the person that told you that.

[quick93]

I was talking to my friends dad about it who works at a chevy dealer and he said to take the in/out hoses out from the engine side of the firewall and just plug the thing, what would that do?
The guy works at a chevy dealer and you expect decent advise? :lol

[billygoat777]

That's exactly what it means. Stop taking your car to whoever told you that was a good idea, except perhaps to run over the person that told you that.


The guy works at a chevy dealer and you expect decent advise? :lol

lol low blows guys, I asked him how to stop the coolant loss and that's what he said I could do



BTW anybody in San Diego have any experience doing a heater core? And can help me?

[Binjammin]

lol low blows guys, I asked him how to stop the coolant loss and that's what he said I could do


Draining all the coolant from the car would stop the coolant loss too, but you at least know not to listen to advice like that. Someone telling you to bypass your heater core isn't helping you fix your car, he's just helping you avoid dealing with it. It's not the right way to go, and seriously, while I'm sure he's a good friend and a great guy and we should all walk on eggshells to avoid hurting his feelings, if you keep listening to him whenever something goes wrong with your car you'll end up with a car that has every light lit on the dash, nothing works, and you won't enjoy driving it.

Let him dick up someone else's car.

[billygoat777]

Draining all the coolant from the car would stop the coolant loss too, but you at least know not to listen to advice like that. Someone telling you to bypass your heater core isn't helping you fix your car, he's just helping you avoid dealing with it. It's not the right way to go, and seriously, while I'm sure he's a good friend and a great guy and we should all walk on eggshells to avoid hurting his feelings, if you keep listening to him whenever something goes wrong with your car you'll end up with a car that has every light lit on the dash, nothing works, and you won't enjoy driving it.

Let him dick up someone else's car.

True man, I get what you're saying.

I won't have to keep asking him, (or anyone) questions soon, next year I am going to be at some sort of technical training class to become a technician, and if that doesn't work out, then hey at least I will have learned a lot about working cars. Sometimes I feel stupid for having to ask you guys simple questions when I plan on working on cars but thanks for the advice man

[NbAmTwE]

I'm having similar coolant lose issues. Have you fully inspected radiator? Take radiator out and run water through it to see if there are any leaks. Like said previously, you want to eliminate all other possibilities before having to rip apart the dash. What about the smell issue? Does it smell a little like burning coolant when the heat is on. If you haven't tried yet, turn the heat on max and follow your nose.

[Binjammin]

True man, I get what you're saying.

I won't have to keep asking him, (or anyone) questions soon, next year I am going to be at some sort of technical training class to become a technician, and if that doesn't work out, then hey at least I will have learned a lot about working cars. Sometimes I feel stupid for having to ask you guys simple questions when I plan on working on cars but thanks for the advice man

Asking questions is how we learn. Keeping our mouths shut is how we stay stupid.

[eightynine535]

.....I could do it now in 3-4 hours but the first time is a bitch...............

wanna do mine?:shifty

[Binjammin]

wanna do mine?:shifty

I will if you want to make the drive to CT sometime.

[russiankid]

I would only bypass the heater if I was stuck somewhere far away from home and the heater core completely blew out. Otherwise, nope.

[andrewbattah]

i did a heater core and and a/c coil in a couple of different cars. It's so true. If you ever have to do it a second time, it will take about 1/3 the time.

What really pissed me off was the a/c coil. I replaced it, evacuated and recharged the system and it was great. No more leak. I totalled the car a month later.


... :/