Heater Core

[ptothej]

I would like to know what the difficulty level is, and what is involved in removing/cleaning/inspecting my heater core? I searched the forums and didnt seem to be able to find the info I was looking for, just wondering if anyone has done it themselves before.

[ARCHINSTL]

I don't think anyone has dived into this before.
I've been contemplating removing the AC core to improve the heating effect, as AC is/will stay superfluous with me (too many $), but have done nothing yet - other probs...
The FSM has info in the AC section only.
Tom M.

[ptothej]

I even went on my dads mitchell on demand or whatever its called and they dont even say anything about it either hahha, its not meant to be done! Lotsa people are just telling me to run some water thru the lines and be done with it (flush it), my brother said it worked good on his 85 with a/c, so I will give that a try.

[ARCHINSTL]

I have some help - actually, quite a bit of help:
http://www.autozone.com/shopping/repair ... 52800520ce
This has a whole section devoted to the heater and its parts. If you have AC, go to the AC section in the same menu (Chassis Electrical) and check that out. You will need to remove some of the AC stuff first to get to the heater core.
Note that this AZ site has photos of the HVAC systems, unlike the POS FSM!
If you do it - please - write a Guide with pix if possible.
Tom M

[takza]

Haven't done this car...but did do another where you literally have to remove the complete dash to get to the heater core. Unfortunately for me...I messed the core up or it was defective...so I'm right back where I started.

The cores are pretty fragile and you don't want to stress them any. All I can say is...have a good detailed manual...buy a quality core...be real careful when doing it not to stress the core...use new heater hoses and new clamps.

If it's not leaking...just buy the Prestone backflush kit and do that? Check the heater valve?

[xirdneh]

i've stripped several tercels and salvaged the heater cores in the process.
its no fun at all getting it out.
i dread the day i need to replace one where re-assembly is required.

[ptothej]

I took the valve off ran some water thru there, made sure that is free flowing, and took the garden hose at my dads and ran water and compressed air thru the heater core itself.. some yellow crap water came out intially.. not alot, and now my heater works without the car having to be fully warmed up, now obviously I wont be able to fully test this until the cold weather starts to hit us, but already it is like 50%ish better, so didnt have to remove the core yay! but I was scared getting those seized on hoses off of the cores piping there, I even crushed the inlet and outlet on the valve trying to get these stupid heater hoses off! I got them somewhat back to a round shape, but still mangled hahah, oh and I took compressed air and blew my heater ducting out.. all I seen was alot of dust, but between that and the core Im getting very good heat compared to previous.

[Petros]

I have removed two of these when I stripped parts cars Tercels. It is time consuming, but doable. the most difficult part I think is a lot of the plastic parts and rubber seals are old and brittle, and it is difficult to get some of the parts out without damage. You would have the same trouble getting them back in for the same reason. I would not do it unless you knew it had to come out, the whole center console and dash came out to make access better, but that was not the time consuming part. That was all the wires, cables and controls that have to be disconnected and removed.

If it is just flushing the core you need, you can do that in the car like you found. You can also fill it a weak acid like vinegar, with the hoses removed, for half an hour or so and flush it out. It will remove most scale and rust build-up. I have found this works well.

Verify your thermostat is working properly, if it opens too far, or does not close all the way you will not get a lot of heat.

You also might remove as many access panels and heat tubes you can from under the dash and blow out any leaves and other junk (like mouse nests) that gets caught in there. Make sure the control cables and flaps are connected and working, and lube them with spray dry lube.

These items usually solves most of the heat problems.

Good luck.

[jetswim]

I had mine flushed at a local rad shop yesterday for $20. He took off the hoses and attached smaller hoses for which he stuck a pressure washer in and blew out all the crap. My wife's 'no heat' problem wasn't fixed though. After the car was warm I checked both hoses to and from the core and they were pretty hot so I deduced it was inside the car. I took out the glove box to see what was happening and the flap (fresh air mix?) that moves the heat from the core to the vents was not operating properly. I manually opened it and voila, HEAT!

[andrea]

Last spring my water pump went and I consequently had everything in the cooling system replaced (hoses, thermostat,sensor). Ever since having that work done I have that sickening smell of anti freeze whenever I use the heater (which is everyday now that fall is here). I have been told this is a heater core issue. I found this website just today for the express purpose of understanding how the heater core works. Can somebody explain what the heater core is and how it functions? Do you think the smell of anti freeze is an indication of a fouled or malfunctioning heater core?

[ptothej]

Im thinking I can do a little bit more.. didnt know where to find/forgot my dads shop had a coolant flusher so I might try again flushing my core, I mean just with some compressed air and garden hose I was able to make it better.. Im not sure if thats the best Ill get or if I could get better.. but it may have come apart which is not happening unless something fails hahah.. but for you andrea the heater core is like your radiator but a 12"x12"x2" square box or smaller, and just like a radiator the hot coolant runs thru there and your heater fan blows the heat into and thru your vents to warm ya up.. so if you have a antifreeze smell, it could be seeping.. usually when they leak they will leak onto your floor, or some vehicles it will leak close to the firewall onto the ground, hope that gives you a general idea.

[ptothej]

Adding to that I suppose I could of said that it is usually located within your dashboard.

[Petros]

Andrea,

Your heater core is like a little radiator that circulates engine coolant through it, is in a plastic box under the dash. This box which takes in outside air and runs it through the heater core and then into the passanger cabin provides heat from the engine coolant. The plastic box usually has a drain for rainwater to exit where it gets in from the grill right in front of your windsheild.

The heater core, like the radiator, gets old and corrodes, and can eventually leak coolant. You may not see it leaking in the car because it goes out the drain, but you will smell it from the heat ducts, and it likely will also steam up your wind shield when you use the defroster.

The heater core needs to be replaced, and unfortunately it is a major job to remove the dash, controls and ducts to get to it. A much better temp fix is to get some radiator sealant or stop leak from an auto parts store (only about $5), and put it in the radiator. It will not harm the engine at all, and will seal up the leaking heater core. Then you have time to consider if you want to go to the expense of replacing it, or the car.

You can also remove the heater hoses and connect them together to by-pass the heater core, but that means no heater or defroster. I do not recommend that unless you live in a warm part of the world. I did that with a car with a leaky core when I was a collage student in southern California. My friends and I near froze to death when we went skiing in Utah that Christmas. I will never do that again!

Good luck

[takza]

Last spring my water pump went and I consequently had everything in the cooling system replaced (hoses, thermostat,sensor). Ever since having that work done I have that sickening smell of anti freeze whenever I use the heater (which is everyday now that fall is here). I have been told this is a heater core issue. I found this website just today for the express purpose of understanding how the heater core works. Can somebody explain what the heater core is and how it functions? Do you think the smell of anti freeze is an indication of a fouled or malfunctioning heater core?

Unfortunately...that smell is a good indication of a leaky core. You could try maybe 1/2 bottle of Bars Leaks to see if that would help it...and crack the windows some. I usually take a marker and draw a line on the coolant tank so when the car is cold...I can accurately check how much coolant it is using....this works as long as the small hose from the tank to the radiator is not leaking any.

With these old vehicles...you really DON'T want to be flushing the coolant system with chemicals or pressure testing it if you can help it.

[andrea]

Wow! Thank you all very much for your clarifications and advice. I am going to tackle the removal today. I have a very nice and underused mechanic that is willing to let me do the job in his shop so that he is there for anything I can't handle. He ordered me a new heater core and I'm determined...no more poisoning my family w/ antifreeze!!!
Happy Hallowe'en All!