Hey guys,

I've been trying to figure out why my temp gauge will randomly shoot up past H. It doesn't seem to be caused by heat alone. I purposely ran my car and AC yesterday during my lunch break with no overheat.

3 days ago, my washer fluid light came on, followed by my non-volume radio working for a split second, followed by my heat gauge soaring past H. Pulled my car over. After 2-3 minutes, the gauge reset to it's normal position.

Obviously, it seems electrical. I run the heat constantly to keep my temps down, but it definitely gets hotter when my gauge spikes. I don't think it's the gauge, per se. I honestly think a fan may stop running for some reason, for no reason, for 20-30 seconds, because the air temp definitely increases.

Looking for a place to start. I may begin by replacing the Radiator Fan relays.

Thanks

 

Try swapping the coolant temp sensor. Pretty inexpensive and can also have an influance on how the fans operate.

 

Could be a malfunctioning stat. Also, I had some funky cluster light behavior when my alternator went bad. You could run the fans continuously and see if it behaves the same way and that will eliminate the fans if it does.

 

Sorry guys. I forgot to mention, in an effort to fix this issue, I've replaced the thermostat, ECT Sensor, and ECT Sender.

 

which sensor? the one with 2 wires on the one with 1 wire? 1 wire one is for the gauge...the 2 wire one is for the ECU. make sure you have good engine ground.

did you bleed the system so there's no air?


the washer...do you have a leak or a crack in the tank?
radio..if it's bose...well they are known to do that.

 

Thanks Danny. I was just listing all 3 because it seems like they may be all connected. Maybe not.

I'm kind of an amateur so I'll check those things. I did not bleed the system. I will try it, though.

Thank you!

 

DanNY had a good point. If you have a vg (gxe) there is an 8mm bleeder screw on the back right side of the intake manifold. Take out the bleeder screw while idling the car up to temp. and topping the fluid at the rad. Once the car gets up to temp. and the thermostat opens wait for any little bubbles to stop bleeding out until you have just fluid and no air bubbles then put the bleeder screw back in place. If you changed both sensors and thermostat an air lock could be quite likely.

 

You guys are awesome. Thank you so much for the knowledge!

 

Is there any reason I can't leave the radiator cap off and run the engine to bleed the air out, or do I have to use the bleeder valves?

 

VG 3rd gens can be hard to bleed, you might have to use the bleeder valve (or most likely). honestly i would spray some deep creep or whatever on the bleeder overnight and try to loosen it in the morning, if it wont budge dont even risk breaking it and just bleed it via the rad cap. if you can loosen the bleeder, bleed it until all the air comes out and straight coolant comes from the hole then tighten it and finish bleeding via the rad cap

 

Awesome. Thank you Chrome

 

Found the bleed screw. Bled the air until coolant came out. Then bled the rad with the cap off. Temp gauge again spiked all the way to the top past H... and the engine was definitely not overheating. Friend says it's likely wiring, which I thought as well. Question is... where do you even begin to check. Like I said, the gauge, radio and wash fluid sensor all started acting up around the same time.

 

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Sounds like a electronic problem. Could be the guage or a sensor under dash.

 

Is this sensor under the dash difficult to find?

 

If its definately not overheating then i guess that would rule out the heater core aswell. Try checking for corrosion on the connectors that plug into the coolant temp. Sensor and clean the connectors. A faulty gauge could be possible but ive heard of tach and speedo's going wonky but not so much the temp. gauge. Your sure you replaced both sensors and thermostat? Are both fan speeds working?

 

The temp sensor that has one wire on it...that's your temp gauge sender. What did you use to seal the sensor to the engine? Did you load it up with massive amount of Teflon tape? Also how are your grounds? Wiring all clean? Just want to make sure it's 100% not over heating right?

 

if i recall a capacitor or something goes bad on the gauge cluster sometimes and can cause those issues, my temperature needle would spike past H and the tach would flip out everywhere then work the odd time, in the end i believe it was just the gauge cluster

 

This forum is awesome. Thank you guys a ton for your help! My next day I'm home and it's light out, I'll give some of these a try.

 

UPDATE

So obviously this thing has been throwing me for a loop. It's getting hotter here in PA and over the past few weeks, I noticed that running my AC seemed to actually keep the gauge much closer to Cool.

Running the heat, or no air at all, seems to have the opposite effect. Eventually, running the heat, it will spike all the way up past Hot

Today, on my way home from work, it spiked again, corrected itself after I pulled into a lot. Then I decided to test my AC again. The needle dropped all the way below Cool in a matter of seconds.

THEN, the moment I flipped off the AC, my needle returned to normal temps.

I'm starting to thing that my vent air is directly contacting a sensor or something! What do you guys think? Is that even possible?

 

Doubt it - the only thing remotely plausible is that maybe you've somehow got your cabin air blowing directly onto the back of the gauge cluster or something and that somehow a bad capacitor or whatever on the cluster is being affected by the air (which is highly unlikely and almost impossible).

I think you probably just have a wonky gauge cluster. Grab a replacement and swap it in before you go on wild goose chases investigating more involved and difficult tasks.

 

JamesEastTX has a few clusters in the classifieds. Maybe worth checking out.