Engine not coming to normal operating temp
I've been having an issue for the last couple of YEARS with my cooling system, but have ignored it because whenever I take it in, they say nothing is wrong. Here are the symptoms and what I've done:
- Prior to issue, normal motor operating temp is 91 deg C (A tick below halfway on temp gauge)
- Ever since the issue started, my engine temp likes to stay around 82 deg C (about 1/4 up temp gauge)
- When I put the car in engineering mode, the coolant temp often fluctuates erratically (I've seen it jump from 82 to 90 in a split second)
- Sometimes when the motor is idling, it gets to normal temp (91 C), but when I start driving, it typically goes back down to 82 C
- About two weeks ago, the temp gauge wouldn't move from COLD, I got a "Contact Dealer" code, and the AC turned itself off (I could not turn it back on either). When I got to work, I popped the hood and the motor was barely warm to the touch. On the way home from work, same situation, but halfway home, temp gauge started to go up and code cleared.
- Figured I had a bad tstat, so I had it replaced. Right after that, motor started coming up to normal temp again (91 C) for a day, then returned to 82 C, like previously.
Anybody have any ideas on what could be wrong? I find it hard to believe that the coolant temp can fluctuate so much within seconds as engineering mode is showing me.
2009 G8 GT
35W HID, LED fogs, custom front/rear Pontiac symbol badges, sharkfin, BlueStar Bluetooth, GXP front end, GXP diffuser, x-pipe, straight through mufflers with helmholtz chambers, RotoFab intake , Eibach springs, FE3 shocks/struts, BMR rear subframe inserts