Temperature gauge

Asked by Feb 12, 2017 at 05:56 AM about the 1998 BMW 5 Series 540i

Question type: Maintenance & Repair

While driving suddenly gauge goes fm
normal running temperature to max high
temp. For several minutes then returns to
normal why?

4 Answers


Sounds like you have air trapped in the cooling system. BMW's cooling systems are very fussy. They do NOT like to be run hot. I believe there's a bleeder screw at the plastic coolant recovery tank (which tends to crack and leak). If you're unfamiliar with this you should take it to a shop that specializes in imports or your local BMW dealer. Don't take it to a gas station type of garage or chain type of garage. They'll have no idea of what they're looking at on this car! My Nephew learned that lesson the hard way with his '98 528i. HTH. -Jim

1 of 1 people found this helpful.

Several minutes? Once it goes into the red, you need to shut the car off and have it towed to the garage. Like JS mentioned, do not run it hot, as the head will warp and you can crack the block. Let's hope you didn't damage the head gaskets, etc. Replace the all the cooling system parts. Then change the oil and hope for the best. You probably have a leak and or air in the system due to low coolant. The expansion tank is always a culprit as they crack.

1 of 1 people found this helpful.

The above answers are correct, but I would first check the temperature sending unit, if there are no leaks under the car. If there is air in the system, fluid had to come out somewhere if you don't already have a cracked head gasket and blowing the antifreeze through the exhaust.

1 of 1 people found this helpful.

could be a sticking thermostat iv seen this happen. fixed 2 with the same problem of your complaint last week.

1 of 1 people found this helpful.

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