Running Hot, Odd.

[ChampagneMD]

OK, '97 Suburban, Big Block. New water pump, TStat, replaced temp guage sending unit, new clutch fan. No leaks, coolant full.

These temps are as the guage reads;

Running on back roads or highway; 190, with A/C 200
Running in slow traffic but moving; 200-210, with A/C 210-220
Coming to stopped traffic after cruising with A/C on, 235-240.
Rev to 1500 RPM and temp comes down to a more normal range.
Turn A/C on while already in traffic, 210.

Went to dealer while it appeared to be running hot. Hooked up to the handheld and the computer says 204.

Very annoying! The tech says that in this truck the aux. fan is A/C pressure activated, not temperature. However, when I threw the idler pully a few weeks ago she got mighty hot and the Aux. fan did kick on.

Ask away!

[SpitAndDirt]

Do you still have orange Dex Cool in your coolant system? Do you have a crusty radiator cap or a brown stained coolant overflow bottle? Your problem might be with the coolant more than anything else. I would have the cooling system professionally flushed, and the system refilled with green antifreeze. I have a 96 Z71 and I had some overheating problems. After installing a new radiator, I ripped into the old one, tearing off the side tanks, to expose heavy clogging from a brownish goo that forms because of the previous owner not taking care of his cooling system. I believe your temp should not exceed 215 with AC on sitting at a stop. When crusing, AC ON , 200-205. The coolant should be properly mixed so as to give highest boiling point possible, for extra protection. 70/30 coolant to water I believe. In the event you might need a new radiator, try 1-800-Radiator, I did and it saved me quite a lot of money, the service was excellent, and the the shipping time was like overnight. Hope this helps. -Chris

[SpitAndDirt]

One other thing, if your vehicle is out of warrenty, do not bother to be convinced that you have to put Dex-Cool back in. GM techs know that stuff causes problems, they would switch it out in their own cars, just ask them. It would be way to expensive for GM to admit fault however, because the Orange does not really harm anything, IF you change it out every 30,000miles instead of 150,000miles.

[ChampagneMD]

Thanks for the pointer about the DexCool. I've read a few posts that talk about staying away from it.

I think I'll do a flush and let you know.