5pony0

Hello,

Lately I've been noticing the temp gauge surges once in a while especially after starting it and driving for a few minutes.

It seems to skyrocket all the way up to the redline (270 mark) if not just short of it, then after 30 seconds it will go back to half way mark almost as quickly. After driving a bit further, it seemed to rise a little bit again, then back down.

At first I checked the coolant level, and I could barely see any at the bottom of the over flow tank. I added some, thinking it would help, but it didn't seem to make a difference since it still does it.

Now this may or may not be connected, but on a side note...had a new radiator and heater core replaced at the same time, all hoses are fine, new thermostat (195). 1 month later the heater core fails/leaks AGAIN, so I by pass it. Now it still seems that I'm loosing coolant somewhere since the overflow tank was empty.

Thoughts?

mattkoly

keep putting coolant into the overflow tank until you don't have to anymore, sounds to me like there is an air pocket in the system, you may also want to try to burp the coolant system.

mjr46

don't added it to the overflow......it'll only draw that back in after it begins to cool down...open radiator cap when cooled off and fill it there then fill to cool level on resevoir......your t-stat may be lazy..even though fairly new it may be bad... make suree the heater blows good hot heat.. this will determine if there is an air pocket often times

Jfsram

I don't see what is wrong with filling it at the overflow bottle. First fill the rad but after that you can use the bottle.

Unless there is a huge hole somewhere in the cooling system. After a few hot and cool down cycles. The overflow system will bleed every last bubble out of the system.

84GT350owner

i am having a simular problem, i've checked my system and the coolant levels are fine, i just replaced the coolant temp sending unit, and it still does it just not quite as often. i gotta ask 5pony0 does anyof your other gauges surge?? voltage, oil pressure?? im pretty sure if his levels are good his voltage regulator for the instrument panel might be bad....

bruehlc

The coolant temp sensor runs on Ohms (resistance) for a reading. As the sensor gets hotter, the resistance decreases.I really don't think that a sensor would cause a spike on the gauge.That means that if a wire is loose or corroded, it could effect your reading.Having the right coolant level is not going to cause a spike in the gauge, nor is a thermostat. I would look to the wiring or the gauge. I have heard of the ford gauge clusters going bad.

I totally bypassed my temp gauge on the dash for an A-pillar Autometer gauge. I like to know what temp the coolant is really at as opposed to the "normal" reading.

silver91gt

Those are symtoms of an air bubble trapped somewhere in the cooling system, run the car for about 10 minutes without the rad cap on and it'll burp it all out, just be ready to top it up, there will be some coolant that makes its way out the top of the rad.

saleenpride1986

same thing happened to my friends mustang a few months ago. Silvergt has the right idea that worked for us last time. Idle the car with the cap off and let it burp the air stuck inside and that should do it. If not then I'd suggest flushing the radiator, it might have some corrosion inside and it's trapping air underneath or between the fins inside the radiator if it's that bad.

5pony0

None of the other gauges do that....just the Temp gauge.

Ive added more coolant to the overflow tank since I can't get the darn radiator cap off!! When I got a New radiator, the cap must not have been the right one, and the shop guy just smashed it on there anyways. (sigh)

Anyhow...It hasn't been surging yet since adding more coolant.