Temp Gauge Maxing Out at Hot
 

I have a 2001 full size Montero and the temp gauge will slowly pin out to Hot after 10 minutes of idle or driving. There are no check engine or temp lights that come on and the lights are not burned out. I have replaced the thermostat and the sending unit without success. The upper radiator hose gets hot and the lower is cool/warm, which I take as the thermostat hasn't opened yet. Before I throw more money on parts or bring it the dealer, any thoughts if it could be the coolant temp sensor, even thought the temp light doesn't come on? I'm open to any other ideas.

Thx.

GC

Try this simple solution that seems to fix some coolant related issues. If it doesn't work it cost you nothing to try.

1. Park the vehicle uphill as best you can.
2. Take off the radiator cap.
3. Start and run on high fan/heat.
4. Squeeze the upper radiator hose and look for bubbles coming up in the radiator.

It's very easy to create an air pocket in the heater core in the Mistubishi's if the coolant is changed with the car level. Multiple flushes and thermostat changes won't fix it. Just something I've heard of many times before and passed on to others who found it worked.

you are correct...Im wondering did the OP put a to STOCK spec thermostat in..When I say to spec usually 89 degrees C- 190 degrees farenheit come to mind.Did You layer the gasket with sealer? I usually do to make sure it sticks. Other than that It would be a good idea to go over your stuff again.

if the engine isnt overheating (i suspect its not), you have a failed gauge cluster ECM.

many brews is correct. there is actually a t.s.b out on this issue. you cannot change that part yourself. when you change out the ecu it also has the milage of the vehicle stored in it. it has to be programed by a specialist, and you have to send them the new part and the entire instrument cluster. mitsubishi uses a company out of california called SPECMO ENTERPRISES. they have a website, and i'm not sure if they take bussiness from an individual. good luck, greg.....

temp guage maxing at hot
 

Just catching up on the post. Saw this one and to confirm the conclusions, I took my 2002 Montero in when the guage peaked at hot back in March of this year. They checked the engine temp with a laser temperature guage and said the engine was not over-heating. They said the temp guage in the dash was bad, and that I would have to go back to the stealer for the repair. They also told me, "big bucks", which has nothing to do with deer hunting. Been driving her ever since without a problem. Sometimes the guage peaks, sometimes it works find, either way it doesn't effect driving performance. Know I should get it fixed. Will go the t.s.b. route first. Just another Mitsugremlin I guess.

1)using the word "stealer" to describe the dealership is insulting, juvenile, and idiotic.
2)it not the gauge. Its the cluster ECM that requires replacing.
3)its not "big bucks".
4)things fail. Its part of owning a car. If thats all that ever fails (and it probably will be), the car is quite reliable.
5)other gauges are not immune to a failure of the cluster ECM. fuel, speedo, etc. can all fail due to this.

You need to lighten up and be less critical of other posters my senior friend. The guy was only jesting (I think) there's no real harm in that, and the comment is not really all that far from the truth, especially given that he was TOLD from his DEALER, that it would be 'big bucks'. If you are suggesting that it would NOT big bucks, then his comment about 'stealers', may well have been reasonably accurate.
Anyway, I don't intend this to be an argument about terminology, just a kind reminder that people need encouragement to post questions, which are legitimate concerns for a lot of us, and not be slated for a bit of humour. We're not all expert mechanics and we need a bit of confidence to ask, even silly questions, in case somebody more knowledgeable can help us to save money, by doing it ourselves instead of relying on quotations of 'big buck dealers'.

This temp gauge behavior can be fixed by a compitent DIY person. There are couple if resistors on the back of the instrument cluster that need to be resoldered. Over years of use they develop microcracks in the old soldering joints and that changes resistance in the circuit. There are good descriptions of the repair procedure on the forum and in YouTube. Mine started to do this and I'm ready to try the fix (minus the stealership)