All right, here is the deal, I just got my car back over the weekend from a full tune up, today all of the sudden my temp gauge went all the way up, the the "Check Gauges" light came on. The car is not overheating and the fans and everthing is working fine. Any suggestions?

 

What was involved in a full tune up. If they did anything to depressureize your coolant system there might be air in your lines. All you have to do is bleed the air out. Make sure you also have coolant in you resivoir.

 

check the sending unit on the drivers side head near the front of the head it should be a green wire right under the manifold i would almost bet money it is burnt or melted to the header or manifold

or maybe it got sucked into your blower inlet on the dyno, oh wait that was mine, never mind

 

will it hurt the car to run it like that while i take it to the mechanic on saturday?

 

just check out your radiator. See if its full of coolant. If it isnt then there is your problem!

 

the needle is way up out of proportion, even with the car cold it's all the way up. It seems to be a electrical issue. I will try to detach the battery so that the computer can be reset.

 

Sounds like you've got a short in that wiring. The temp gauge is only for driver information. The computer uses a sensor located on the water pump housing. The dash gauge uses a sensor screwed in to the driver's side head. I'll bet the wire is laying on the exhaust manifold or otherwise grounded out in that area. I'm pretty sure that if the circuit is open the gauge will read low and if it's a dead short it will peg it.

 

well, it's all the way up. is this hard to change?

 

What're you thinking of changing? Is the sensor busted? Wiring? I doubt there's anything wrong with the gauge.

 

i have to check first to see if the sensor is bad or wiring. i just wanted to know the level of difficulty that this will incur

 

Sounds like you have air in the coolant lines/passages. Air pockets get real hot real fast, and when they move in front of the sensor, the guage will shoot up, then come back down when the pocket is past the sensor. If you have a few air pockets in the passages/lines, you will get false readings on the guage. Just bleed it thoroughly and you should be OK.

 

If it goes all the way up to 260 when you first start it and stays there, then I'd guess its the temperature sender. My 87 305 did that, replaced the temp sender and everything was normal.

FWIW on the 305 sbc it was between the 1 and 3 spark plugs, right underneath the exhaust manifold. Kind of a pain to get out, took me about 5 minutes of slow wrenching, also, drain the coolant, because if you don't it'll come rushing out. If its the same, and you know the lefty loosey righty tighty thing, you can do it yourself. Before you change it out though, make sure its screwed in all the way and tight, and the wire isn't melted and on that the wire is on the sender snuggly.

 

it's got to be the sensor, the needle stayed all the way up even i just started the car and is cold. Today the car die on me!, then it started right after about 30 minutes. anyhow the tow truck just came for it and took it to the dealer. I will post later on what their diagnose was.