Car temp gauge was fluctuating slowly between max and normal operating temperature. Thermostat works properly, fans work properly. I’m pretty sure my water pump is leaking from the weep hole, and plan to replace it ASAP.
Could a failing water pump make the temperature bounce back and forth like that?
Was probably driving 50-60mph when it initially occurred, but seemed to happened regardless of speed afterwards. Wasn’t an abnormally hot day. Car seemed to be driving normally except for a squeaky new serpentine belt (alternator and power steering) that I tightened today. Disregarded this because it doesn’t drive the water pump or fans.
I tried turning on max heat when it was overheating, it didn’t seem to help much.
Serpentine belt is new and does not run the water pump. Don’t know the condition of the timing belt though. I plan to replace it with the water pump, but no other problems with the car to suggest timing belt issues.
After flushing and burping the system it has not overheated again. I don’t think the water pump would make the temperature rise and fall repeatedly like that.
Could air have been getting in through the weep hole over time, creating air pockets? Not sure if that’s practical, but would explain why it works after flushing.
Worst case I replace the water pump and take it to a mechanic afterwards if it overheats again. Thanks for all the replies btw. Much appreciated.
Speaking from experience my first thought was a head gasket when the temp fluctuates. For me it would cool down again at speed when the pump was pushing the coolant faster. The other thing is a radiator filled with bugs in the front can lose it’s ability to cool efficiently or the radiator could be coated inside.
How would I go about checking the head gasket? I believe oil would be mixing with coolant, so I’ll check for that. Are there any other things to look for?