Heater valve

[n2motorsports]

hi everyone, hope someone can chime in before i just throw parts at this thing.

at idle my temp reaches the high temp mark and only cools down if i rev it or the car is moving.

i suspected the thermostat so i swapped in a new one.  after filling up with coolant, i let the car idle and the temps eventually shot up high again.  i felt the hoses and the one from the expansion tank side was hot and the other side was cool.  is my water pump bad?  or did i get a bad thermostat?  the fan is running the whole time.  also, the heater inside blows cool, though it's on the heat setting and there is a hint of antifreeze smell to it.  

Oh, and no leaks from the water pump nor is it making a weird noise.

anyone else have this issue?

[hoevesruperd]

i would check the fan, even if it turns, it might be dead. you should be able to feel resistance when turning it by hand. if it stops before completing a full turn you're good.

also bleed try to bleed your system

remove the entluftung screw on top of the radiator, let all the air come out by adding coolant continuoulsy. when there are no more bubbles, screw the entluftung  back in and  start the car... repeat if needed.. i'm sure you can find a better DIY then what i just said

if you had a bad thermostat i believe you the car would overheat all the time not only on idle. then again, that means your pump works, maybe not strong enough though

if the car is in good shape and you want to protect the engine for a while, i'd suggest you change the pump and fan. if the M42 overheats you can be sure to have lot more headaches as it has a aluminum head prone to warp with excessive heat.

hope this helps
good luck

[n2motorsports]

i've bleed it 3 times, and took it on a spin, about 25 miles on the highway.  the car's temp needle is pegged on the high side and the heater blows cold air!  once thing i did notice is there isn't much resistance when i turn the hvac knob to the hot side.  could my heater be clogged?  

btw, the fan does spin, with very little resistance.  should i stick a rolled up piece of paper to see if it stops?  is that the test?

[hoevesruperd]

the heater could be clogged but i dont think that would make you engine run hot.
check the temperature knob and links under the dashboard. maybe you have something disconnected.

you could use a rolled newspaper and stick it in there, i dont think that test says much about your fan condition since it depends on how much the journalists in your town have to say! :p

if the fan seems to spin freely when you push it, chances are its fried

does the temperature get stable at a certain degree?

[n2motorsports]

yes.  it's stablizes about 1mm from the red notch.

i read another thread and someone says if the engine is hot and the air is cold, then it could be some temp control valve...i wonder if that's the same thing as this?  #16?

http://www.realoem.com/bmw/showparts.do?model=AF93&mospid=47305&btnr=64_0514&hg=64&fg=15

[n2motorsports]

maybe this? its a thermostat as well?

http://www.realoem.com/bmw/showparts.do?model=AJ93&mospid=47318&btnr=64_0135&hg=64&fg=99

[hoevesruperd]

yes.  it's stablizes about 1mm from the red notch.

i would check the thermostat first. see at what temperature it opens in boiling water

but dont know much about the temperature control

[bmwpower]

Leaky heater core or heater valve can let air in the system and cause an overheat, but in my experience it will overheat whether driving or at idle.

What about that recall heater valve thingy against the firewall?  If that siezes shut and doesn't flow coolant back to the head, it would seem that it could likely cause what you're seeing, no?

I would be careful in your troubleshooting.  These heads apparently do not take well to hot conditions for too long.

[n2motorsports]

okay, im lost, but i need to fix one issue at a time.  right now, there is no heat, it will blow hot air intitally then eventually become cold.  this leads me to believe that the heater valve is closed and won't allow hot coolant to flow thru the core.

what's the best way to test this?

I know that the heater valve is controlled electronically, so if i remove it, i suppose i can put some power to it and see if it opens?

is there a way to test it while it's on the car?  maybe stick a water hose into the inlet to see if it come out of the outlet?

what's this heater valve recall someone mentioned earlier, i couldn't find more info on it.

thnaks.

[hoevesruperd]

what if you bypass it?  hot air would go through the heater and you'd know its not blocked or leaking and that the valve is your problem.

i agree that you have 2 seperate problems and that you should take care of them as different issues but honestly i think the engine overheating is way more important for now than the no-heater... whatever temperature it is outside (i ran my car with no heat at -19 Celsius to go on a date with a girl and she's still turned on)

[n2motorsports]

I've been bleeding daily since Saturday and then magically, on Monday, the heater starts blowing hot air and the needle is solid at the notch right before the midway point.  

However, now I'll randomly see a dime size pool of coolant over night and I've had to on 2-3 occassion, refill the expansion tank, it was near empty 2x.  Today, I just topped it off to the indicator mark for "cold," it was about 2 inches below that mark.  Other than the dime size coolant, I am not seeing where else I can be losing coolant.  No damp areas in the cabin, no coolant lose behind tranny or under intake manifold. No smoke, no water in oil or vice versa.  Is the system just finally purged out all the excess air?  I did find it weird that when draining the coolant, I got nearly a gallon of old coolant, doesn't our cars have about 3 gallons?  
Typically I measure what goes out, so I know what to put back in, since flushing, I've put in well over double the amount of coolant taken out.
Sorry for the long post, hopefully, it'll end up helping someone else out.

[demon510]

I know my e36 holds almost two gallons.  I know you have bleed the system, but how are you doing it?

[n2motorsports]

fill it up, turn car on with heater on and let it idle and keep adding coolant.  then i'd rev it up a bit and add more coolant while letting air purge from the bleeder screw.  then i'd go for a drive, and let it cool down a bit then repeat the process.

[pifane]

Interresting post...but not fixed my problem:

I have changed :
-Fan clutch
-Thermostat
-Hose
-Radiator

I do :
-Bleeded the system
-Checked coolant

I push on the gaz. Sometimes, at 60 mph, my engine is overheating. Sometimes, when im at 100 mph, there's no problems!

Others times, when im running smootly in the street at 20 mph, my engine is overheating.

The heater core is fully working : When the engine is hot, IT like sahara in my car.

Timing chain cover gasket have been replaced after failing. My engine is about 335 000 Km (209 miles).

Someones have an idea?

[pifane]

Also...There 2 thermostat for this engine : 92 and 88 degree. It can make a difference?