[plano-doug]

So we replaced the Coolant temp sensor and that helped a bit but it red lined on us again after two days so we just put the Blue Devil Head Gasket stuff in it as the last thing we are going to try....every other part of the cooling system and anything that could cause overheating has been looked at.

When it red lined, were you sitting still, or moving? How fast?

I'm wondering if you don't have an intermittent relay on the cooling fans. Did you swap out any fan relays in all this?

Doug

.

 

[plano-doug]

Moving at interstate speeds and no we have not switched out fan relays.

If it's pegging the needle at highway speeds, it's probably not a fan issue - interstate speed pushes lots of air into the engine compartment (ie, thru the radiator) even when the fans are off.

I'm thinking it's either a temp sensor issue (sensor or wiring), or you have a sticky thermostat. I know it's new, but you have the symptoms of one that's stuck.

If there's a temp sensor issue, I would expect you to see the temp needle jump to the red state. Do you recall - were you watching the needle - when it went into the red? Did it jump? Or climb into the red? If it moved smoothly, even if quickly, I'd say the temp sensor / wiring is good...which brings us back to a stuck thermostat.

I know it's a PITA - I just put a thermostat in one of my 2002 Impalas - but I'm thinking the next step is another thermostat, barring you selling it

Doug

.

 

[plano-doug]

It was a smooth climb in to the red. We replaced the temp sensor a few days ago and that helped a bit and we have a fail safe thermostat in it so it should be flowing even if it is stuck.

I agree, a fail safe would stick open.

As this point, you're down to only a few things left to try.

Check the wiring on the new sensor. You say the new sensor "helped a bit". I'm wondering if you have a broken sensor wire that is intermittent. Can you pull the wire out of the loom and inspect it?

Has the cooling system been pressure tested? Are you seeing any coolant loss?

Maybe try another shop, perhaps a radiator shop. Give them the history of what you've been thru. Maybe they can ID the cause of the needle pegging.



Doug

.