Overheating Problem - 91 BMW 318i

The cause was uncovered: loose contact for the temperature needle caused what you see here.

Looking for input as to what the cause of this problem may be. The problem is inconsistent, and re-occurs at different times and situations. Most frequently occurs after warming up from a cold start, and seems to occur less at higher speeds (when getting more air cooling), and blasting the heat on high seems to help a little also. Car is a 1991 BMW 318i, possibilities are the thermostat, or possibly the cooling fan clutch which is weak and is causing the fan to also be weak and not blow lots of air.

Looking for input, Thanks.

Category:

Autos & Vehicles

Tags:

• overheating
• problem
• 1991
• bmw
• 318i
• coolant
• high
• water
• temperature
• thermostat
• radiator
• cooling
• fan
• clutch
• system

[chillenlikeavillain]

@RPFEngineering you're right, this was exactly what was causing the problem. it has been resolved for some time now, but I appreciate the input nonetheless 

[RPFEngineering]

If you remove the instrument cluster, you will find that the contact for the temp gauge is held on by a 7mm nut, that tends to back itself off. This is what causes the jumping needle. I was having this same issue, and once the cluster was removed, I took the nut off, and used some loctite (very small amount) to make sure the nut would not back off and tightened it down. I haven't had one problem since. Not sure if you have already resolved this, but thought I would share since this is common

[chillenlikeavillain]

@elf51183 also forgot to mention that the cooling fan clutch was also replaced because the previous one seemed weak, but didn't really change anything.

[chillenlikeavillain]

@elf51183 going to install a new sensor tomorrow, it's a bit hidden which is why I haven't done it yet. If that fails the next thing I was going to check was the wiring all the way from the sensor to the cluster/dash. I don't think there is an obstruction as the car doesn't actually overheat when this occurs (water temp remains around 100 celcius). If all that fails then maybe it's the cluster/water-temp gauge itself or its mechanism...that's all we've thought of so far...

[elf51183]

From what i can tell, only reason ur temp sensor would go nuts like that is ur sensor is messed up...you have an obstruction in your cooling system...ur wiring is messed up or it wasn't bled correctly...

[chillenlikeavillain]

@elf51183 no air in system, was bled before and after thermostat was done.

[elf51183]

You should bleed out the air from ur cooling system..