maguills

My temp gauge has been going crazy for the past couple of days. It starts out in it normal position(half way) Then it'll shoot up to hot for a couple of seconds then down to 2/3rds then slowly back to half then back up to 3/4 then to above the H then back down to half etc... I just changed the coolant, thermostat, water pump and timing belt a week ago and I the temp gauge was fine for the first five days and then started acting up. After a day of driving around with the heater on just to be safe and the gauge bouncin around all over the damn place i get home and pull the keys out and instead of the gauge going down it it shoots above the H and stays. I put the keys back in and turn the truck on and the gauge goes down to half way, I pull the keys out and it goes back to above the H. The heater also stays on when the keys are out. So I try and start the truck up and it won't start. It cranks over just fine, but nothin'. The next morning(today) it starts just fine. So I'm drivin my kid to school and the temp gauge starts dancin around again. All the sudden the truck dies and the temp gauge is way above the H again. And guess what happens next... it doesn't start. I had it towed to the shop and they said in their preliminary testing that it wasn't getting spark or fuel. I asked if the temp gauge was still showing overheated and the guy didn't know. So my question is: Is there some kind of safety mechanism to shutoff the motor and/or prevent the motor from starting when the coolant temp gauge is reading extremely hot? Thanks in advance. Joe

Yukon

When all my coolant came out while wheeling, the truck stalled when it got too hot. It was really scar, but I cooled things off, and refilled the radiator, and it started back up. It didnt feel at all like a computer thing...

tunnelmotor99

Sounds like either the coolant temp sensor is going bad or there are air pockets in the cooling system.

Kiroshu

Just from what you are saying in the post it sounds like when the repair work was done the engine was not properly filled with collant and bleed. There could very well be some air pockets in it causing theses issues. Was this problem around before the timing belt and water pump job? Everything plugged in correctly? The thermo stat the right one for the truck? Was it installed correctly and not backwards? May need to look at temp sensor. Could have a voltage problem. Broke wires? Swapped connecters? Faulty sensor itself?

gdutch

If you think there's air pockets in there, take your radiator cap off WHEN THE ENGINE IS COLD, start it up, and stand by with a container of 50/50 antifreeze and water. Unless the coolant is right there at the top, it needs more. You should see it bubble down a few times, and try revving the engine a few times (use the throttle cable). When it stays full, it's good.

maguills

Thanks Fellas for all the help!

The problem has been solved!!!! The main ground for the ECU was loose and therefore causing all kinds of problems. The grounds tight now and the truck purrrs like a kitten.

Thanks again!
Joe