Help Overheating kinda

[drifter420]

Well.. I toppeed up my car with some prestone all makes and model bout a year ago and notice my car is runnin a lil hotter since..

long story short...

went thru Timmies drive thru on last wednesday, 3rd car. ( so wait time from start to finish is bout 5 min. )
notice the car went way above normal.. seems like 220F ( not sure as the middle mark is 90c and usually doesn't exceed by that much in stop traffic unless I sit in rush hour for 15 min. or so )

can't see any water leak under water pump ( but it's situated in a dumb place that doesn't give me access to see right under it )
water pump pulley is making some weird noise ( but was changed less then 2 years ago )

running 180 T-stat ( bout 4yrs old ) car usually is bout 171F while cruising along on the highway ( 1 mark before TDC 90c )

Any suggestion on a.) how to find out if it's the thermostat or not? I heard to do a boiled in water test to see if it opens and how large the opening is.. anyone know what it's suppose to be?
b.) I may do a coolant flush.. but it ran on dex cool, and been scared from all the post I read bout Dex cool clog.. any suggestion on other coolant? ( G-05?? And where to get in Ontario Canada )

P.S.
Its a 97 Bonneville SSEI 3.8L supercharge

P.S.S. EDIT= I also the car runnin a lil hotter then that.. and if I wait at traffic light and start accelarating, the needle will start to climb close to 90C ( TDC ) till I keep driving for bout 4 min. then it will start going back down.. but at times will sit just a lil higher then the 3/8 mark I'm accustomed to seeing it sit on

 

[Ray H]

Never mind whether you can see an exterior leak. Are you losing coolant? If the volume in the cooling system is decreasing, the only other explanation is an internal leak into the sump. The GM 3.8s are infamous for developing intake manifold-related leakage that goes into the cylinder bank valley and drains into the motor oil. Glycol is very corrosive to lead-babbit bearing material. You need to find out what's going on if you're losing coolant. A used oil analysis will tell you whether you have glycol intrusion into your motor oil. If you're not losing coolant, you may merely have nothing more than an air lock from improper bleeding at the last coolant changeout.

 

[drifter420]

I checked the coolant resevoir and the mark is exactly as it is.

Hummm... so maybe I'll have to rebleed it..

thanx RayH...
Yea.. the N/A has issue with LIM and UIM gasket failing due to coolant issue.. thankfully my S/C is on top so I don't have to worry bout it that much.

Last oil change a month ago didn't show any signs of water contamination and neither has the dipstick

thinkin of doing a coolant flush later on.. Is G05 ok with Dex cool? Does anyone know where I can get them in Ontario Canada? ( basically are they worth the $$ or dex clone is fine? I"m scarred of this whole cloggin from dex cool I've been reading.. lmao )

 

[Chris142]

Your fan is not coming on.

 

[mechtech]

I think Chris is right - check out your fan, possible relays, activation sensors, and maybe the ECU.