Weird Temp Gauge

[Backwoodsballer]

Hey guys,

I am having a very odd situation with my temp gauge recently.

When I start the car it will come up to temp and sit at normal temp all day long. Yesterday I took it out to stretch its legs and about 10 min into the cruise the temp gauge was climbing very quickly so I pulled over and shut it down.
With the key in the on position and the car off it was reading normal temp, when I would restart the car it would climb all the way up to high.
I got out and fiddled with the gauge sensor wire and started it again and it was reading normal (after about 5 min of sitting with the car off) I proceeded to drive the car trying to get it to show overheating again (hard driving) and it never did for the rest of the drive.

Is it possible that there may be an air pocket in the system? Recently I swapped in a new sensor for the ECU and the gauge hoping the would fix the issue (maybe they did and I have an air pocket left?)

ANy input would be greatly appreciated!

 

[super.secret.supra.club]

Try "burping" the system once more with heater on full blast. Just like you said, there may be air pockets still in the system.

 

[SupraTrbo89]

I wonder if your thermostat was stuck closed.... They are relatively inexpensive and easy to replace. But yea, I would burp it 1st. There are instructions on this forum if you do a search.

 

[Backwoodsballer]

Okay I will search that procedure and burp it after work today. I would like to do a coolant flush before spring anyways so this might be a good time to start fresh

 

[suprarx7nut]

Remember that burping is only a bandaid for a bigger problem. The system shouldn't require a burp unless it's got a leak or unless you've modified the system somehow (odd pipe routing or something).

I'd try renting a cooling system pressure test kit from your local store. I've had that show me leaks I couldn't otherwise see. A very small, slow leak may go unnoticed and relieve the system of enough coolant to get an air pocket that could trigger a temp spike on the gauge.

A stuck thermostat is a possibility too, but I'd start with the pressure test. If you replace the thermostat only to find out the problem persists, it's likely you'd have to drain the coolant again.

 

[grsupra87]

Mine was doing the same thing. I burped it. Changed Thermostat. Replaced Radiator cap. Checked overflow lid gasket and hose for spooge/blockage/leak. Flushed coolant system and replaced all the fluid. It still does weird things, like the fluid bubbling in the overflow bottle, or running out of it after parking, but only once in a while. One time while at a red light the gauge went up pretty high, and the INSTANT I moved like 2 feet it dropped back down and never came back up. I know the HG is not the culprit, it was replaced 20k ago and done right. This spring when I get it out of storage I will try the pressure test, because I am out of ideas.

 

[suprarx7nut]

Mine was doing the same thing. I burped it. Changed Thermostat. Replaced Radiator cap. Checked overflow lid gasket and hose for spooge/blockage/leak. Flushed coolant system and replaced all the fluid. It still does weird things, like the fluid bubbling in the overflow bottle, or running out of it after parking, but only once in a while. One time while at a red light the gauge went up pretty high, and the INSTANT I moved like 2 feet it dropped back down and never came back up. I know the HG is not the culprit, it was replaced 20k ago and done right. This spring when I get it out of storage I will try the pressure test, because I am out of ideas.

I'd put $5 on that being a BHG or a small coolant leak. Good luck!

 

[Backwoodsballer]

I burped the system last night a bit. It took some coolant but less than I expected it to take. I might try to pressurize the system like mentioned above to see if I have any leaks. I would hate to flush it and replace the thermostat only to have to do it again.

I will keep you updated as I go. Also when I flush the system I read that the plug in the block (I believe on the exhaust side) should be removed, is this true?

 

[suprarx7nut]

I will keep you updated as I go. Also when I flush the system I read that the plug in the block (I believe on the exhaust side) should be removed, is this true?

I would do that to flush it. You'll get a lot of fluid out of the block plug. I was surprised just how much fluid remains after draining only the radiator.

 

[SupraTrbo89]

You can get away with a thermostat update without draining the coolant but a little will spill out so just hose it off. Get a OEM quality thermostat and not one from pepboys. Also, when you replace the thermostat it is directional even though it fits both ways so just make a mental note while removing the old one.