no HEAT, after waterpump seized....help!

[audiquattrot]

Last week I was driving, and all of a sudden a loud screeching noise & my dash lights came on (battery, brake, etc). Pulled over, and had the car towed to my local E30 shop.

Upon investigation, it turned out the waterpump pulley had seized. It was replaced w/ a new one, and the car drove fine....until I realized there was no HEAT at all.

Heat worked fine prior to this incident, so today my shop replaced the thermostat, bled the system for almost 2hrs (tons of air pockets in the system), and replaced a couple sensors by the thermostat (not exactly sure which ones).

None of the above solved the issue. Any ideas what the problem could be before I start replacing every part under the hood?

TIA.

[browntown]

Huh, that's odd. I'd squeeze the coolant hoses to the firewall. Usually you can hear the fluid moving back and forth. Might be possible one of the linkages from the hvac controls broke. I'd consider taking a peak to see if the heat control is actually activating the heater box.

[Farbin Kaiber]

Did the overheat or pressure cause damage to the heater valve?

[jlevie]

Bleed for two hours? Tons of air pockets in the system?

Done the correct way it shouldn't take more than 20 minutes to bleed the cooling system and most of that time is waiting for the engine to reach operating temperature. Difficulty in getting all of the air out makes me wonder if there isn't a head gasket leak that is pumping air into the cooling system. Air in the cooling system can result in no heat.

[audiquattrot]

yeah we thought that might be the case as well, but there is no evidence of oil in the coolant, nor is the coolant level going down. Wouldn't the car blow smoke if the head gasket was toast?

Is it possible the heater core could be clogged up w 20yr old gunk, and just needs to be flushed out? The heat was working fine prior to the waterpump install. I know the radiator was removed to have that replaced.

[audiquattrot]

btw the car never overheated.

[Ceeker]

btw the car never overheated.

u may still have air trapped in the heater core or the block. not uncommon. did you bleed the system with heat full on defrost?
Also helps to rev the engine while the bleeder screw is open once the car reaches op temp. it help push air from areas further back in the system forward.
You replaced the waterpump, maybe faulty? but doubt it.

Before you go to all the trouble. I just went through this with my car: low heat issue.

changed: thermostat, heater core, heater tap, dash heater switch, heater valve in engine bay, bled system. my thermostat was the culprit. Make sure you get an 80 degree Celsius or 196 F. stat and make sure the arrow is pointing up. Sometimes aftermarket stats don't work properly. then make sure you bleed the system thoroughly. Now I have warm air at least in -10 degree weather. Recirculate helps it to get hotter.

[audiquattrot]

u may still have air trapped in the heater core or the block. not uncommon. did you bleed the system with heat full on defrost?
Also helps to rev the engine while the bleeder screw is open once the car reaches op temp. it help push air from areas further back in the system forward.
You replaced the waterpump pulley but did you ever think your waterpump has packed it in?

yeah we bled the system w/ the heat full & rev'd the engine constantly w/ the bleeder screw open once it was up to temp.

Any other suggestions on how bleeding the system better (assuming there isn't another issue)?

[jlevie]

yeah we thought that might be the case as well, but there is no evidence of oil in the coolant, nor is the coolant level going down. Wouldn't the car blow smoke if the head gasket was toast?

Those are only three of the possible symptoms of a head gasket failure. The most common is a failure that only pumps air into the cooling system.

[jlevie]

yeah we bled the system w/ the heat full & rev'd the engine constantly w/ the bleeder screw open once it was up to temp.

Any other suggestions on how bleeding the system better (assuming there isn't another issue)?

Try:

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 2000-2500 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.

[Ceeker]

great write up!:)

[Need4Speed1299]

jlevie kicks ass!

[audiquattrot]

thanks for the writeup jlevie. I tried bleeding the car again w/ the front jacked up using jlevie's writeup, some air came out and then a constant stream which indicated the system was bled. Unfortunately no heat still. I felt the hoses going in/out thru the firewall, and only one was hot.

That leads me to believe that a valve controlling the heat must have broken? The blower motor works at all speeds.

I had a friend look over the car as well, and he pretty much ruled out a blown headgasket.....

[audiquattrot]

i had an issue w/ my old iX's heater not working (but that was fan related)...so I replaced the blower motor and all was good.

As I search old threads, I came across someone who had a similar issue as mine, but his fan would intermitently work....and blow cold. He replaced the blower motor, and it started blowing hot.

Logically it doesn't make sense, but wondering if any of this has to do w/ a possible bad blower motor?

[jlevie]

thanks for the writeup jlevie. I tried bleeding the car again w/ the front jacked up using jlevie's writeup, some air came out and then a constant stream which indicated the system was bled. Unfortunately no heat still. I felt the hoses going in/out thru the firewall, and only one was hot.

That leads me to believe that a valve controlling the heat must have broken? The blower motor works at all speeds.

I had a friend look over the car as well, and he pretty much ruled out a blown headgasket.....

With the engine off and ignition on, you should be able to hear the heater valve click as you turn up the temperature knob from full cold.