m42 overheating?

[KenC]

after removing the thermostat again I toss it into some boiling water.. Opens up like a teen! haha. Put everything together and threw water into the system. This time I filled up the water from the upper rad hose. Then proceeded the tank with the heat on hot until I no more air bubble where found on the bleeder screw. Start up the engine with it on full heat and on number 1 setting for the fan. Close the cap and left the bleeder open and rev it a few time until I didn't see anymore bubbles.

The heater was working well (got pretty hot). I also took note of the radiator and the lower hose. The radiator eventually got hot and the lower hose got pretty hot as well (thermostat works!). But my gauge is between the 1/2 and 3/4 again. I think I have a bad cluster or something.. Going to change both temperature sensor soon. The aux switch never turned on my fan btw..

You can't have the bleed screw open when you're running the car to heat up the engine. An open system will cause your coolant to boil.
Read my bleed technique. I still think you have air in the stem. That, or your water pump is bad. You shouldn't have major temp gauge fluctuations under any circumstance.

[e30BimmFeister]

my 318i was all good till today drove it noticed it te temp needle all the way 4/4 the upper hose was pretty hot like it had been talked about i pulled over let it cool down, it cooled so i drove a little ways to see if it would change then i saw it went back up. i pulled over again i checked again but the coolant level wasnt high so i was thinking the thermostat is jacked? any ideas?

[keada714]

my 318i was all good till today drove it noticed it te temp needle all the way 4/4 the upper hose was pretty hot like it had been talked about i pulled over let it cool down, it cooled so i drove a little ways to see if it would change then i saw it went back up. i pulled over again i checked again but the coolant level wasnt high so i was thinking the thermostat is jacked? any ideas?

From what I understand a thermostat that is close will not allow much water circulation thus your top rad hose would be cool or warm. I believe there is some circulation from the heater core back to the radiator. The cooling system for these car are a pain in the ass.

To be honest i'm not even sure if I fixed my "over heating problem". I'm not sure if it was a bad connection to my temp gauge or something but I just replaced the thermostat and flush and bled the crap out of the cooling system. But right now my needle is a little over the middle mark sometimes. I believe this is happening because I might have a bad clutch fan and my aux fan isn't kicking on. I doubt the car is over heating because I'm not consuming any coolant and the car runs strong and good. The only real solid advice I can give you is to never let your car get that hot.. These car are very sensitive to over heating and you could have blown your hg or even cracked the head. Best of luck to you though!!

[e30BimmFeister]

overheating

it never got hot though i pulled over everytime and saw that it wasnt really overheating

[keada714]

you said that it was pretty much at the 4/4 mark, which indicates that it is over heating correct? remove the thermostat housing and go ahead and test your thermostat to see if it does even open up. Then start trouble shooting other areas..

[b*saint]

After two thermostats in two different m44/m42 engines (pretty much Identical) Mine always sits a needle's width after the halfway mark. I consider this normal for these engines.

[Dj Buttchug]

you could consider running more water and less coolant. mix maybe 60/40 or 70/30. water dissipates heat better than coolant. might be enough to bring you right to the middle.

use distilled water

[keada714]

I consider it normal as well. I no longer worry about it to much but I do keep an key out for it. I run a bottle of water wetter and also run maybe about 80-20 water coolant right now.

[e30BimmFeister]

yea it was 4/4 but it didnt seem it was overheating idk but im not drivin it i will try waht keada said and diagnose the prob in diff areas...thanks guys ill get back with how its going

[lookitsranday]

Old thread but I'm having same problem, heater doesn't blow hot, it overheats like mad, same symptoms any resolution on this? Help!!!

[keada714]

Redo the whole cooling system is my advice and get a e36 alum rad!

[mbulsa]

my car just overheated a couple weeks ago because my belt was slipping and not spinning my water pump. Went out and got a new tstat, housing, belt and what not, and after bleeding it my car goes slightly above 1/2, but then creeps up to 3/4. You can see the needle bouncing every once and a while, so what i've read from this thread so far is to try to bleed it more. I already did it twice but I guess I'll try some of the techniques in this thread. Very helpful.

[slaterd]

Let your system "burp" a bit and get some air out. Go to autozone and ask them for the coolant "burping"kit. Its just an oversized funnel that adapts to a radiator cap that has a hole in it and a clamp. Poor some coolant in the funnel and run your car for 10-15 minutes.