Flucuating Temp. Gauge - Toyota Nation Forum : Toyota Car and Truck Forums

WhiteRabbit · 03-30-2006, 12:31 AM

My temp. gauge will seemingly stay low for longer than usual sometimes, then jump a few notches, then jump to normal operating temps. Then it'll drop again as I'm cruising and go back to normal as I slow down or brake.

Is the thermostat messed up? my gauge cluster? or a sensor?

88 LE · 03-30-2006, 03:46 AM

Could be either one of those.

1. Check the ECT (engine coolant temp) sensor with a DMM and temp gun (if you have one).

2. Remove the thermostat and dump it in a pot of boiling water. The thermostat should open.

Probably a better idea just to replace it.

Mike Gerber · 03-30-2006, 05:13 AM

I agree with 88le on just replacing the thermostat. From the symptoms you describe, it may be stuck in the open position. Replacing it is a fairly simple DIY task. I would recommend a Toyota OEM thermostat and gasket to insure you are getting a quality part.

Mike

WhiteRabbit · 03-30-2006, 08:21 AM

I figured the thermostat being stuck would cause longer warm up times, just don't quite understand how it goes from normal to cool, and vice versa.

My coolant is pretty shitty colored too, can that affect the thermostat?

Not sure if I need to do another radiator flush (did it a couple of months ago), or if a slight oil leak on the back of the block is leaking into the coolant somehow...

desi_prodigy · 03-30-2006, 08:31 AM

u need a new thermostat,,i had the same problem,,change the thermostat,,and flush the coolant system

88 LE · 03-30-2006, 09:31 AM

Quote:

Originally Posted by WhiteRabbit

I figured the thermostat being stuck would cause longer warm up times, just don't quite understand how it goes from normal to cool, and vice versa.

The thermostat is not opening properly. IE: stuck thermostat.

When the car is moving theres more water flow as the water pump is spinning faster. Thats why your noticing the temp drop when your moving and it go up when you slow down.

I've had the same problem, except the thermostat was stuck closed.

Quote:

My coolant is pretty shitty colored too, can that affect the thermostat?

Rusty color?

You can try using a flush additive the next time you do a cooling system flush.

Quote:

Not sure if I need to do another radiator flush (did it a couple of months ago), or if a slight oil leak on the back of the block is leaking into the coolant somehow...

If oil is leaking and mixing with coolant, the coolant will be milky.

As for the oil leak on the back of the block, check around the valve cover. It could also be a leak from the power steering pump since its near the back of the block.

WhiteRabbit · 03-30-2006, 09:58 AM

^alright, thank you much =)