Engine gets really hot and takes a long time to cool after a trip

CHRISTOPHER SA

MEMBER
1993 BMW 320I
2.0L
6 CYL
2WD
MANUAL
117,800 MILES

After finishing up my front suspension work I took the car out for a drive and ended up going to a friend's house 25 miles down the road. When I returned home later that evening I did a short run to the shops. I then parked the car in the garage and about an hour or so later I went into the garage to get my bike to go out on it.

I walked by the front of the car and touched the right fender and found it very, very warm to the touch. It was not hot enough to remove one's hand because it was too hot but it was much more than just warm. Being really puzzled about this I opened the hood of the car and felt the engine block (where the VANOS system is at the front of the block) and it was very hot.

The left fender was also very warm. The heat of the engine had gone through the metal and affected the whole of the front of the car. The only area not affected was the hood. That was barely warm. 2 hours later and the engine was still very warm, as were the fenders and the front of the car.

While the car was being driven the temperature gauge did not show any abnormal behavior with the needle in the middle.

This morning I went out and started the car to see if the fan worked and it did.

One of the things I have done when doing stuff to my car is I have added a bottle of Prolong to the engine oil. I believe that if I had not done so the engine may have seized.

The car did exhibit slight hesitation at low gears/rpm but I just took that to be from lack of running over the last year or more.

I suspect that there may be an issue with the thermostat and I have already purchased one and a bunch of other things with a view to overhauling the cooling system of the car.

Even so, I find it very puzzling that the engine was so hot with no problems showing with the temperature gauge. Any ideas?

Note: Since I purchased the car the temperature switch on the passenger side of the radiator (mid-way down on the plastic part of the radiator) has never been connected. Only recently have I purchased a new one but have not fitted it yet.

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

If it only sat an hour, that doesn't seem unreasonable. If the gauge isn't indicating an issue and there is no evidence of it overheating, it may be normal. I know my own vehicle can sit for a couple hours and if there is limited ventilation, and don't ask me why, the fenders are always warmer to the tough than the hood. I suspect it is due to the exhaust manifold locations. If it isn't actually overheating, I would drive it for awhile and see how it runs for you. Is there anything else that may indicate an issue?

Here is a link that shows in general how a thermostat is replaced. I doubt you need it, but figured I would add it just in case.

https://www.2carpros.com/articles/replace-thermostat

Let me know.

Joe