so its still over heating [Archive] - Bimmerfest - BMW Forums

: so its still over heating

10-21-2008, 09:15 AM
i have bleed bleed and re bleed the coolant changed the hoses is thier anyhting else when i changed the head i did the thermostat as well could it have broken the thermostat when it over heated from air in the coolant ??

10-21-2008, 09:20 AM
The Fan clutch is another thing that could be bad. Does it cool down to almost normal wile driving at highway speed and only over heat at idle? If so, the fan clutch is a very good bet.

10-21-2008, 09:22 AM
iits over heats no matter what its doing it sucks whats a good way to test teh fan clutch?

10-21-2008, 09:28 AM
If it over heats when at highway speeds then your fan clutch is not the problem or not the only problem. I have never tested a fan clutch. I went by the symptom and just replaced it. And it worked. But in your case there is some other cause. Remove the thermostat and put every thing back together (Leaving the thermostat out. Start it up and see what happens. if it does not over heat then your thermostat is bad or was put in backward.

10-21-2008, 09:30 AM
im gonna hate my self if te thermostat is in backwards im just scared cuz i jsut built a new head and putt it on and its been over heating since then and i dont wanana **** up the head cuz i put to much time into porting and polishing it

10-21-2008, 09:34 AM
Well, you would not be the first to put one in like that. It is an easy mistake to make if we are going to fast just to get er done. LOL...

10-21-2008, 09:54 AM
well i just took the thermostat out and ran it it still over heats so im completly lost on what to do

10-21-2008, 05:34 PM

I don't know if this helps,,,, but try this, if you have the system (cooling) torn down at the moment, remove both the top (out from block) and bottom (into water-pump, block) hoses at radiator, then take your garden hose at really high and put into radiator at top opening, see how fast and clear the water circulates out the bottom opening ( the one which goes to the waterpump/thermo. if it is clear and little to no hesitation of exiting the radiator, then try this,,, do you have a coolant drain bolt/plug on the block? if so, get it open and drain it.
then using the garden hose again, leaving the block plug open, put the bottom hose back on the radiator(waterpump/thermo hose), then fill the radiator (its ok if water spills out from the top as you are doing this as you havent started the car yet. (oh yeah, keep the thermostat out of the system for the moment), now start the car and run just for a few minutes, just long enough for the water to get sucked into the motor from the radiator and swirled through the block, it will exit the top hose which you have disconnect from the radiator, and also the coolant plug space at the block which you took out earlier.

I know this works , cuz I did it on mine and the system bled perfect after doing that procedure. as i had effectively "flushed" the block and radiator.

only run the car for a few minutes when you do this, it wont take long to flush out.

then remove the garden hose from the top opening of the radiator, and only run the car for about ten more seconds to push the plain water out, or as much as it will in that ten second time frame.

hope it helps,