Engine problems in the GXP

[DavidS1567]

Strange stuff tonight.

Driving to my 2nd job tonight, the message "A/C system off to protect engine" popped up on the DIC. I parked the car a minute later and noticed the engine temp gauge wasn't showing any heat (needle was all the way down). Odd. Popped the hood, engine seemed like it was at normal temp for a 15 minute drive. Then I went inside to work.

Three hours later: I went to start the car and it took about 5 seconds of cranking for the engine to start. Starter motor was running strong. The same message then popped up on the DIC and the temp gauge still didn't show a reading. On the Southern State I ran OnStar diagnostics and they confirmed something was wrong with the cooling system - no other info available. (gee, thanks.)

Since the car was running perfectly, I drove straight to Sun Pontiac. After parking, I wanted to move the car up a few feet. When I went to start the engine, it cranked and cranked and cranked without starting. After about 8 seconds of cranking I turned it off.

I'm thinking it's a PCM issue. What do you guys think?

[Zeus]

Bad coolant temp sensor screwing up the PCM perhaps?

[jimmy C.]

I think I saw an article about the Dextron coolent causing problems by clogging-up
coolent passage ways.

[DavidS1567]

Dealership called this afternoon and said it started up fine for them today when they drove it into the garage to check it out. So it seems that it starts when cold, but not when warm. They did the power steering hose recall work today and they're going to do the rest of the diagnostics w/ the engine tomorrow.

Jimmy,
You saw an article about dexcool? You must not have been googled enough. Dexcool is notorious for screwing up engines. Thankfully, I had the dealership do a flush 2.5 years ago and I still have my majorguard warranty. Everything should be covered.

[jimmy C.]

DEXCOOL.....that's what I was thinking of. No wonder I got nothing on a search.
Sometimes I get that old flashback.
Thanks Dave.

[DavidS1567]

Just heard from the dealership, bad coolant temp sensor.

Occam's razor.