Overheating and Leak under Thermostat Housing..

[BMWLOCO]

Fellow Enthusiasts:

Putting the E30 back together after Timing Belt, Thermostat, Belts, Hoses, Water Pump... etc..

Started to fill it up with coolant and the expansion tank is full, Idled it for a few, Overheating a little, shut it down and let it cool off the the night.. Today, Expansion tank empty and started filled it.. Ran the engine and it overheated again, almost to the red. Hoses are tight and then I notice a slight leak at the bottom of the thermostat housing, right above the hose. I don't see anything from the hoses.. I know there is probably some air in the system that need to be bled out, but what about the thermostat housing? I believe it's torqued pretty well. I believe there is a rubber seal there, might not be settled in..

Should both sides of the thermostat housing touch each other when properly tight? I have a small gap and I can see the thermostat..

Also..

The console is out and so is the dash. I'm just trying to slide the windows down to get some air while I work in the interior and NOTHING.. Feels like there is no power to the windows.. I tried all the sides and interchanged the switches.. NOTHING.. No Blown fuses.. etc.. Any Ideas?

Thanks in advance!

[jlevie]

While other causes are possible, the first things that comes to mind is a failure to properly bleed the cooling system and/or a thermostat that is in backwards. the spring end of the thermosat must be facing the engine. The best way to bleed the cooling system is to use a vacuum fil system, but lacking that use:

1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500rpm for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.

If this is an 88 or later car, in-op windows (and HVAC blower) can be caused by bad unloader relays or a bad starter unloader switch.

[BMWLOCO]

Thanks Jim.. I'll try that tomorrow.

BTW.. My Blower is good, I started the AC. Where are these relays that i need to check, and the unloader switch?

R>.

[jlevie]

The unloader relays are in the fuse box. The unloader switch is part of the starter solenoid on an 88 or later car. Cars built before 9/87 don't have an unloader switch.

[BMWLOCO]

Sounds Great.. I'll get on that as soon as I get the cooling issues solved.

Anyone have a picture of the thermostat housing and the gap that's in between the two parts?

Thanks..

[jlevie]

When correctly assembled there should be no gap between the cover and thermostat housing.

[Huff]

You might have the seal on the wrong side. I've done that before..

[jlevie]

You might have the seal on the wrong side. I've done that before..

I don't see that causing a gap. Failure to remove the old seal (installed on the wrong side), the wrong seal, or even the wrong thermostat seems more likely.

[BMWLOCO]

Seal was in correct, thermostat was in backwards. No more gap and no more leak. Refilled, ran it, heater on and got to normal temperature. Now for the windows.

Thanks a bunch.