Engine temp gauge acting funky

[Nav13]

The previous owner had told me that the gauge doesn't read correctly and said at full temperature the needle will only go to the 3rd little bar which didn't seem like a big deal. But the other day the needle jumped up to half way while I was sitting in traffic and then it came back down after a few minutes. So now I never really know if my engine is actually over heating or if whatever is broke is just starting to work for a sec and then crapping out again. Has anyone ever had this kind of problem with their temp gauge where it reads a low temperature when it should really be reading half way, any clue as to what needs replacing?

[ShermanEF9]

overheating would be if its at the "H".... anywhere below that is normal. half is where it will usually rest.

[5000Audi]

Originally posted by ShermanEF9
overheating would be if its at the "H".... anywhere below that is normal. half is where it will usually rest.

did you even read what he said?


Well id say it almost overheated if it gained that much then dropped back down again..if i was you i would go out and get an aftermarket temp gauge and sensor.. then you can see real time temps correctly

[Redlyne_mr2]

Fluctuation of the temp gauge is normal however it sounds like yours is fluctuating more than it should. Normal operating temp is well below the 1/2 mark however I would look at rebleeding your coolant system if it hasn't been done recently.

[Nav13]

Well in the last 3-4 weeks that I've owned the car it has only ever jumped to the half way mark twice. So it's not a regular thing where the needle fluctuates. Normaly it just rises slowly to the 3rd mark as a car would normaly warm up and then just sit there. I just figured there was some sensor that has crapped out. Redlyne I will look into the folder the last owner gave me of work done on the car, if it hasnt been done lately I'll get that sorted out, but I have a feeling it is something else.

edit: woops I just reread what you wrote Redlyne. Wait so going up to the 3rd bar when at optimal operating temp is normal? Because if that is the case, then my gauge is working fine and the car was just running alittle warmer when it jumped up to half way.

[Redlyne_mr2]

Originally posted by Nav13
Well in the last 3-4 weeks that I've owned the car it has only ever jumped to the half way mark twice. So it's not a regular thing where the needle fluctuates. Normaly it just rises slowly to the 3rd mark as a car would normaly warm up and then just sit there. I just figured there was some sensor that has crapped out. Redlyne I will look into the folder the last owner gave me of work done on the car, if it hasnt been done lately I'll get that sorted out, but I have a feeling it is something else.

edit: woops I just reread what you wrote Redlyne. Wait so going up to the 3rd bar when at optimal operating temp is normal? Because if that is the case, then my gauge is working fine and the car was just running alittle warmer when it jumped up to half way.
I don't have a stock cluster in mine so I had to look at a pic to refresh my memory.
http://jdmautodepot.com/accessore_img/IMG_0278.JPG
Normal operating temps are around the 4th-6th line. On a track day you'll be up near the middle. It's rare for gauge on the cluster to stop working but it's common for the water temp sensor to fail. That being said it sounds like everything is working properly and that there is in fact air or even a tiny tiny leak in the system. When there is air in the coolant system the car will generally run fine until you put it into a situation that allows the temps to climb (heavy acceleration, idling on a hot day). The thermostat would also be the cultprit it may not be opening properly. By not openinng properly the engine does not receive the required coolant necessary for hot temps.

[Nav13]

Ah that makes sense, thanks for taking the time to throw up some pics too. I will rebleed the coolant system and report back.

offtopic question, but is that 2nd cluster out of a 93+(revision3 mr2)? Just curious because of the boost gauge, even though I know stock boost gauges are very inaccurate that one looks dope.

[Ashkente]

Second cluster's gauge says "HKS" ;)

[gretz]

could be bad wiring or ground...in my beater my gauge goes up and down with the signals and to the max hotness when the highbeams are on lol...

[mr2mike]

If it's making large jumps, then the sensor isn't sitting in fluid 100% of the time. Sits in air, temp doesn't rise properly on gauge. Then car heats up fluid reaches the sensor then bam, gauge needle jumps.
Also check your T-stat. could be busted but those typically fail open not allowing the car to reach op. temps.

Personally I would see where your coolant level is at and re-bleed. Bleeding is a PITA with these cars.

[Nav13]

Originally posted by Ashkente
Second cluster's gauge says "HKS" ;)

How did I not see that.


Originally posted by gretz
could be bad wiring or ground...in my beater my gauge goes up and down with the signals and to the max hotness when the highbeams are on lol...

nothing seems to change with the temp gauge when turning on the lights or high beams, but...



Originally posted by mr2mike
If it's making large jumps, then the sensor isn't sitting in fluid 100% of the time. Sits in air, temp doesn't rise properly on gauge. Then car heats up fluid reaches the sensor then bam, gauge needle jumps.
Also check your T-stat. could be busted but those typically fail open not allowing the car to reach op. temps.

Personally I would see where your coolant level is at and re-bleed. Bleeding is a PITA with these cars.

I think Redlyne and mr2mike are right, I went and checked the previous work records and the temp gauge sensor had been replaced back in 05 when the car had 196k, car has 224k now. So I doubt the sensor crapped out again but you never know. Either way I'll start with re-bleeding the system. So is re-bleeding the coolant such a PITA that it's worth getting the dealership to do?

[mr2mike]

No don't go to the dealership. There's just a special way for mid-engined cars. Follow the service manual and it's no problem, just a few more steps than a typical car.

[Redlyne_mr2]

Here's a link I always use.. once you know how to do it it's super easy.. just takes time.
http://lovehorsepower.com/MR2_Docs/mr2_bleeding_cooling_system.htm

[Nav13]

Thanks for the help guys, I'll let you know how it goes.