Overheating after new thermostat. 1984 318i (m10b18)

[LazerSquid]

Hey everyone, I've been running my car without a thermostat for awhile now because every time I put a thermostat in this car, it overheats! Yes, I'm putting the thermostat in right side up, and I've replaced the water pump recently (6 months ago), but I can not get it to stop over heating.

When driving with the thermostat installed, it will heat up to just past the third mark on the temp gauge, and hang there. If I put it in neutral while driving and rev it up to near redline a couple of times, then it rapidly drops down to just below the middle notch, then begins to overheat again.

When I leave it running in neutral in my drive way, it inches up to the middle mark very slowly; no quicker than it did without a t-stat, and then stop at the middle mark, sometimes going above the middle mark, but only about a needles width, but the hose below the t-stat (rad to t-stat) stays frigid cold. Atleast when driving it gets a little hot.

Also, when i'm driving the car, the heater works very well and blows very hot until it gets to the third mark, then the heater starts blowing ice cold.

I'm completely perplexed by this and have no idea what could be causing it. Am I not bleeding the system correctly? How am I supposed to bleed the system? I have to get to work tomorrow morning, and this is my only car (no busses or taxis in my town either) so I'm really hoping I can get this fixed tonight, even if it means putting the old drilled out t-stat back in it.

[323i E30]

Bleed by:


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 2000-2500rpm 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.

.

[nowloadingrage]

Heater core hoses hooked up backwards??
Just something to check. Yes I've done it when switching motors out.

[paul blagrove]

Rad blocked or head gasket ??

[hotdish]

Heater core hoses hooked up backwards??
Just something to check. Yes I've done it when switching motors out.

That shouldn't cause the car to overheat, that just makes the heat not work. It might make the car harder to bleed, but I ran my m30 swap car like this before I found out my hoses were backwards without overheating.

[Vanos Baku]

Check radiator, probably clogged
Or at least get fins washed

[bostonbmw]

Check the thermostat is functioning properly, put it in some boiling water make sure it opens. I once installed a new(behr) thermostat that was defective and I chased my tail trying to find the problem.
Once you have verified that the thermostat is working and installed it bleed the system of any air. Make sure your heat is set to hot to allow coolant to pass through the heater core.When you have topped off the coolant squeeze all the hoses with your hand to try and force any air in the system up towards the bleeder screw. It can sometimes help if you jack the front of the car as to raise the bleeder screw so its higher up in the coolant system.

[Arget]

Hi! I wanted to find out if this problem has been solved, since my problem is exactly the same. And if she decided, how exactly?

[82eye]

Hi! I wanted to find out if this problem has been solved, since my problem is exactly the same. And if she decided, how exactly?

does it overheat in traffic and not on the highway or open road ? if so your fan clutch has probably given out.

[Arget]

does it overheat in traffic and not on the highway or open road ? if so your fan clutch has probably given out.

Thanks for the answer! But it cools down to normal in traffic, and if I'm not driving fast, the engine cools down too. But the higher the speed, the more the engine overheats.
Sometimes it helps to cool the engine if revving in neutral gear.

The belt on the generator was also changed, the tension was made good. But the problem was not solved.

[82eye]

Thanks for the answer! But it cools down to normal in traffic, and if I'm not driving fast, the engine cools down too. But the higher the speed, the more the engine overheats.
Sometimes it helps to cool the engine if revving in neutral gear.

The belt on the generator was also changed, the tension was made good. But the problem was not solved.

roll up a newspaper and shove it into the fan blades while the car is idling. if it stops the blades your fan clutch has had it. if the fan shreds the paer your problem is probably still the thermostat or other issue.

[Arget]

I checked the cooling system a bit the other day. I took off the radiator, all the pipes, the thermostat, washed everything, cleaned it, then poured water and rinsed the system properly with it. I leaked some dirt.

But! First, I installed a radiator without a fan to flush the system. As a result, the car was never able to overheat while it was standing and revving the engine. The thermostat was opening and the lower nozzle was hot. As soon as I washed everything and put it back together, the problem returned while driving.

And for some reason it helps if you turn off the engine and then start it up again, after these actions the temperature begins to drop slowly, the thermostat opens, and the temperature stays normal for a while. Then the engine begins to overheat again and restarting again helps to lower the temperature.
If I don't do this, then antifreeze starts to fly out from under the radiator cap due to overheating.

[82eye]

check your fan clutch.