'92 BMW - Heat gage suddenly jumped into red zone

Hi. I'm posting this for my son. He has a 1992 BMW 325i. When he was driving yesterday, the heat gage was fine, and then suddenly jumped into the red zone. He pulled over asap and looked under the hood, and there was a burning oil/exhaust smell. When he dropped the hood down to close it, a small chunk of plastic fell out from under the car. It looked like it could be a piece of a fan blade from the rad fan, but not really sure. (We both know very little about cars.) He left it parked on the side of the road and is now afraid to drive it, so will probably get it towed somewhere.

The car has coolant in it, and it wasn't steaming or anything... Overall, it seems to run quite well, so it was odd that the gauge suddenly jumped into the red zone without any warning.

Any ideas at all as to what the problem could be?

Any suggestions would be much appreciated.

Thanks.

 

First, believe the gauge. It is safest that way.
Second, if he thinks there may be a piece of fan that came off, then treat it as if the fan is coming apart.
So now we got an overheating car that is dangerous to whoever is under the hood because the fan could start and fly apart like a 410 shotgun.
I support the idea of getting it picked up and taken to a pro.

Your question was to say what could be the possible problems.
Here goes. Keep in mind these are only guesses. Just throwing some ideas out there.
I dont think it is the fan because it would take a more gradual time for it to heat up when he was driving because of the natural air flow over the rad. Also, if the fan came apart, I would think he would have heard the pieces flying around in the engine compartment.
For it to heat up that fast I would suspect the combustion chamber heat could be a factor. Possible head gasket failure.

Or. Could be something simple like a malfunction of the heat gauge.

Good luck and congratulations on the good call to think safety first.

 

There are a couple of scenarios.

The first is the car didn't heat up, but the gauge gave the impression it did. It could be the gauge which would account for a sudden jump into the red zone.

The second has a lot more involved. The gauge was right and the car did heat up. That could be a drive belt on the water pump or a water pump that went out. The latter usually involves an external leak, but not always.

A thermostat could be acting up and need replacing.

Or the cooling fan went out which would account for the broken part, if it was the fan blade.

I think I would play it on the safe side and tow to a shop for repair.

Hope this helps,

Bob

 

Thank you both for your replies! Thought I should get back to you with what had happened.

He had the car towed to a shop, and he needed a new fan and a new water pump. Thank goodness it wasn't the head gasket!

Thanks again. Your replies were appreciated.

 

Thank you Marie 12345 for getting back to us with the outcome. That is nice.

 

The clutch fan on the car is prone to failure. If you check out bimmerforums.com you will find a lot of threads about fans exploding and taking out radiators and hoses.

While you are replacing the water pump, you should probably replace the thermostat as well since it is a plastic piece and prone to failure also. They have a new metal piece you can buy which isn't that much money and it give you piece of mind.