overheating

[LKTe30]

I have a 90 325i and it has an overheating problem that i can not figure out. I replaced the water pump, thermo and radiator already. The clutch fan seems to be ok but the car seems to be overheating to quikly for that to be the problem.
So here is what happened one day when I was checking my fluids I forgot to put the resevoir cap back on. I drove the car for a little while and when i noticed the car getting hopt i stopped saw the cap and put it back on. The tank had not run dry yet but since then it overheats all the time. I tried replcaing all the above parts and bleeding the system all to no avail. The car will sit at idle and not overheat to quikly might take 15 minutes but as soon as you start to drive or rev the engine the temp goes right to the red within a couple of minutes even when driving. Also it seems when the car is idling that water is not flowing through the hoses. And I am not getting hot hot air ever from the vents with the heater on high.
Thanks for any help.
mike

[kowalski]

try bleeding the system you probably have air pockets in the block. also could be a jammed thermostat when you isntalled it might be worth it to check that as well. good luck. your in richmond eh? im in white rock.

[e30Matt]

Make sure your thermostat is a) good and b) not in backwards.

[LKTe30]

i am almost positive it isnt the thermo. as for bleeding it i'm pretty sure i had gotten the air pockets all out. i am leaning toward it being a clogged heater core, but if any one has any other ideas i would appreciate the help.
thanks
mike

[LKTe30]

so i removed the heater core today and i think i am getting close to where the clog is since when i started to disconnect the hoses to the core the top on started leaking coolant and i have only been using water while trouble shooting the problem. is there an easy way to check if the core is clogged and of the 2 hoses the one black and one silver which id the return and which is the feed.
thanks again for the help
mike

[T.Dot E30]

You could have just by passed the heatercore to check to see if that was your prob.

The two coolant lines going into the car, just use a connecter and join them.

Also I dont think its the heater core, it doesn't do much for the cooling system just gives you heat.

[bichmgnt]

I had the same problem recently. Bleeding was the answer. But not your ordinary let the air out at the bleed valve kind of bleeding. I did that at least six or seven times. I even tried running without the thermostat, bleeding it, and then running it and it seemed worse, if possible.

What I eventually did was, with the thermostat out, take off the upper end of the hose between the thermostat and the water pump and make that the top of the water pillar. I closed off the gaping hole on the thermostat with a bag and a rubber band. I then took the hose off the upper heater outlet (which is fed from the back of the engine), closed it with a bolt, and put a hose on the now open heater core outlet to make its end higher than the top of the engine. Then I poured water into the hose going to the water pump and blew through it to get water coming out of the heater and out of the reservoir. Once that was full of water (a couple times) I put the hoses back on everywhere, bled it at the top of the thermostat and ran the engine again without the thermostat. This time it stayed nice and cool. Finally! Took it for a drive and it never got out of the blue. Went back and put the thermostat in, bled it normally and took it for another ride. Normal operating temps at last (actually it seemed low - between 1/4 and 1/2), the heater works and all is well.

That was probably an extreme way of handling the bleeding but it worked for me when I was having a problem. I have to do this again in the near future and will probably do sometning similar to make sure the engine and head are full when I'm done.

Good luck.

Steve