Replacing the E30 Heater Core and Valve

[JinormusJ]

Thermostat has to reach a certain temperature to open and allow coolant flow to enter the heater core if the system has been allowed to depressurize (you've allowed a large amount of coolant to drain/escape). Air trapped in the system almost ALWAYS gets stuck in the heater core and will not allow heat to blow; a working heater is one of the things that you can use to verify you've bled your system correctly and your thermostat functions

[DatUtahGuy]

So if you bleed the air out of the cooling system and allow the vehicle to get fully warmed up(halway on the temp gauge) after replacing the core and valve but DONT drive the car you wont have heat? That's what happened on mine.

[blazinxpk]

So if you bleed the air out of the cooling system and allow the vehicle to get fully warmed up(halway on the temp gauge) after replacing the core and valve but DONT drive the car you wont have heat? That's what happened on mine.

i replaced my heater valve a few weeks back. after putting everything back together, i started my car and filled up coolant. it felt like the air still wasnt hot, so i thought the valve that i replaced wasnt the problem. i still continued with filliing up coolant and went for a drive. the air was now getting hot and this was the solution to my problem.

so i guess you and i had the same issue.

[JinormusJ]

Kind of...

During idle, the engine never actually gets to rated operating temperature. Say, the thermostat is rated at 80*: the engine, at idle, gets to about 75 or so, and is not hot enough to open the thermostat after a fresh bleed. Normally, idling the the engine at 3k increases flow and temperature enough to open the thermostat. Driving the car after a fresh bleed is much the same concept

Top off coolant
Bleed
Rev to 3k rpm til heat blows
Enjoy fresh heater

[bastianshaw]

i was under the impression that the coolant that goes to the heatercore bypasses the thermo

[steve68]

Getting ready to perform this myself,

I have the interior stripped, fixing some rust and small holes in the drivers side floor board, today I broke out the welder and when I opened the door the was the funny green fluid on the nice white floor,

where the best place to get a heater core??

[sweet6e30]

i did this and ripped out the pooched valve, i plumbed direct new rubber coolant lines as a coupler between a pair of aluminum pipes and the heater core outlets ..that passes through the firewall, clamps and rightstuff sealant..... 3 years later, no problems at all.

Only thing with the way i did this is that it blows hot air when fan is on in summer too, but hey my AC was removed anyways, its a 4 door with a sun roof,....everything goes down and open to enjoy the road on a drive anyways.

[sandlock]

Any leads on places to purchase new valves? they seem to be unobtanium these days. Behr supposedly won't make more for a while; there has to be some place that stocks them.

[blazinxpk]

Any leads on places to purchase new valves? they seem to be unobtanium these days. Behr supposedly won't make more for a while; there has to be some place that stocks them.

i went to pick n pull (junkyard) bought two of them incase one didnt work. $15 each. purchasing them new might be pricey.

[steve68]

or hard to find, along with the heater core,

[dogsbark26]

Try here.

[steve68]

thats it but man there expensive,

[cholyoke]

I got everything out and the original o-rings have a square cross section and the new ones that I got have a circular cross section. They have the same ID/OD. Are the new ones the wrong o-rings?

Edit-got them from Pelican (here). Part number is different than what Real OEM says to use (12 on diagram here).

[DatUtahGuy]

My o-rings were "squared" or pancaked because they were so old, the new circular ones worked just fine

[cholyoke]

Thank you. I don't want to have to do this twice. Did you just use motor oil to wet the o-rings?