Do yourself a favor, check the ground wire that goes from the intake manifold to the middle section of the strut bar, close to the firewall. I had a similar issue, except I didn't start replacing parts, and while looking at the coolant temp in my AEM EMS, I noticed the temp was normal but the temp gauge would read really high. To my surprise, I didn't have this ground wired bolted down, once I bolted it down, woala, problem fixed!

Keep us posted on your findings.

 

oh okay I will check thanks

 

Are you saying the gauge pins all the way up while both fans run then you get overflow out the reservoir?

 

definitely air in the system

 

Ok i have had this issue before. Gauge is showing hot at idle or sitting in traffic but is fine moving along at speed. Eventually though it just read high.

Here is what it was on my car after checking coolant and refilling burping, new OEM cap etc....I checked with my cable and logged temp. To my surprise the temps were normal despite what the gauge said.. So i checked the sensor for the gauge which is right on the thermostat housing facing forward under the radiator coolant hose.

Turns out the wiring had coolant leaking from the clamp onto it. Tried cleaning but did not work very well ( this is after replacing the defective clamp) Ended up replacing the connector to the sensor and the sensor ( this was to be safe ). I made a boot for the connector from a vinyl shield that came on one of the probes for my multi meter, just the right size and sealed everything very well. Soldered the new spade connector to the existing wire. I also took off the water neck and thoroughly cleaned up the hose connection. Used 120 grit to get the corrosion off.

It has been 6 years since the fix and it hasn't had any issues at all. Gauge reads normal even on hot Atlanta summer days

Hope this helps

 

Thanks do you mind if you send me some pictures of that

 

I checked everything and they seem they look okay. I am going to order the radiator cap, I've never replaced it.

 

Always wondered why Mitsu would put two temperature sensors in the thermostat housing. I still don't know why - maybe they have too much money. But if this ever happens to me I now know to check the readings from both sensors.

 

yeah I put to much money on parts :/

 

Let me rephrase.

So the only reason you think it's over heating is because of the reading on the gauge?

 

Yes thats correct and I used a laser gun to read the temprature. Its only the gauge thats faulty my car doesn't over heat.

 

It might be a loose ground wire i am looking into the wiring.

 

OP,
Any updates?


interesting! i started experiencing a similar issue where my gauge would read high but on all of my logs I log a max of 205 on a full 3rd gear pull. usually my gauge would climb if I go higher in the rpm.
having said that, the ground to the intake manifold isn't currently connected...need to make a new wire due to running an ams f1 now days. Will check this tomorrow!

 

Update:
I put a grounding wire directly from the battery to one of the thermostat bolts. I also re-torqued the head studs to 90 ft.lbs in case any of them was lose since I recently changed the head gasket (20 miles ago) and they were all spot on!
It's also worth mentioning that I am running a mini radiator with a single slim fan, and the fan seems to be working fine. I also left the rad cap off the radiator during idle and no air bubbles were showing (for 10 mins).

While idling everything seemed fine, no over temp indication on the cluster, however, the min I started moving the car out of the drive way, the cluster gauge started increasing till it went to full hot. in the mean time, my logs were showing a max of 206F at most.

Any other ideas?
Thanks

 

im having similar issues, i just ordered a new fan and planning on installing it this weekend. im curious to see if this will resolve the problem.