Please tell me why I'm still overheating

[AlexMaldonado]

So I've got a '91 318is that's been having issues overheating lately. I flushed the radiator, but noticed the distilled water wasn't circulating when I first started so I decided the water pump must be bad. I've now replaced the water pump and thermostat and the car still overheats and still doesn't seem to be circulating coolant. Anyone know what the issue could be? It's also got an electric fan that's working right so I know that's not the issue

[gespinal0301]

Did you bleed it at all?

[AlexMaldonado]

Well I drained all the old coolant out, and what was left came out with the water pump if that's what you mean. If bleeding it is a different process than that I haven't bled it, but would like to know how.

[CanadianDirty30]

Did you bleed it at all?

Well I drained all the old coolant out, and what was left came out with the water pump if that's what you mean. If bleeding it is a different process than that I haven't bled it, but would like to know how.

I think he means, have you bled the air out of the coolant after refilling the rad? Having air in the system could definitely contribute to overheating issues. Also might want to consider replacing the thermostat, simple process that ended up solving my overheating issues.

[gespinal0301]

I think he means, have you bled the air out of the coolant after refilling the rad? Having air in the system could definitely contribute to overheating issues. Also might want to consider replacing the thermostat, simple process that ended up solving my overheating issues.

Yeah this is what I meant. There should be a plastic bleeder screw to the right of the radiator cap, with the engine on and starting to warm up open it slightly to let the air out. Then keep adding water/coolant to the radiator and repeat the process over again until no bubbles come out

[MrBurgundy]

Air, or tstat is stuck. IDK the condition of your car, but a bad head gasket can cause overheating problems.


You should just go ahead and replace the t stat. After that, open the bleeder, with the engine on, then fill it up until its full. Then, it may take a minute for the thermostat to open, when it does, it may take some more coolant.

Also, a tip for bleeding, jack the front of the car up and turn the heater on while you're bleeding.

[AlexMaldonado]

I replaced the thermostat at the same time as the water pump, but didn't know about the valve by the filler cap. I'll do that today and follow up. Thanks for the tip!

[e30s50dan]

You have to bleed the hell out of it..may take a couple days to get it right.

[Metallated]

I don't think air in the system is causing the problem.. IIRC M42's are pretty good at self bleeding...

Do you have the issue at speed or only when still? Perhaps the issue is a bad fan clutch?

[CanadianDirty30]

I don't think air in the system is causing the problem.. IIRC M42's are pretty good at self bleeding...

Do you have the issue at speed or only when still? Perhaps the issue is a bad fan clutch?

Thats what I was thinking, but sounds like he's got an e-fan according to his post so that would eliminate that possibility

[LowR3V'in]

backwards thermostat

[AlexMaldonado]

I owe you guys my life! I bled the cooling system and it's running like it just came off the show room floor! It held it's temperature at idle for several minutes and the test drive was perfect too! Much appreciated!

[varg]

I don't think air in the system is causing the problem.. IIRC M42's are pretty good at self bleeding...

Hmm. I recall my M42 being much harder to get bled properly than the M20, which pretty much bleeds itself in one go once you get it up to temp and crack the bleeder open.

[MrBurgundy]

m42s can be a pita to bleed.

I did a flush on my m20 and it pretty much bled itself.