Why does the temperature gauge on my car barely move?

My temperature gauge barely moves even after a good run. My Mitsubishi Shogun is a 2000 GLS 3.2 DI-D. Is this common?. Also my heating is only lukewarm is this connected?

Asked on 4 April 2019 by Keith Parry

Answered by Honest John
It's 19 years old so unless the cooling system has been flushed a few times during its lifetime there will be a lot of sludge in there. First job: a flush and reverse flush using radiator cleaner. Buy a replacement bottom hose so you can take the old one off and drain it properly. Then fill with plain water and see if you still have a problem. Do the fans come on when the engine gets hot or do they come on immediately? You may have to replace the temp sensor/sender switch. Is the coolant actually flowing through the heater matrix? Once it's all working properly, drain off the plain water and re-fill with the correct coolant, running the engine with the expansion tank cap off in order to purge any airlocks.
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