98 aurora overheating

I have a 98 aurora with 150K miles..radiator began leaking and replaced it. Shortly thereafter it began running warm and now is overheating. It has been in the shop for a week. backflushed, new thermostat, 2 different "block" checkes ... both negative...still overheats. They are now saying it is a possible head gasket, but it runs like a champ and I am out of ideas. There have been water circulating noises in the dash the last 20K mile but nothing leaking and I have heat....Any ideas?

Sloshing noise in dash(pass. side)is A/C condensor runoff that pools on a 'shelf' area when the drain hole clogs and is not related to the overheating. Have a smog tech check for exhaust gases in the coolant reservoir when cool or slightly warm. Also, see Timesert Update thread.

I have a 98 aurora with 150K miles..radiator began leaking and replaced it. Shortly thereafter it began running warm and now is overheating. It has been in the shop for a week. backflushed, new thermostat, 2 different "block" checkes ... both negative...still overheats. They are now saying it is a possible head gasket, but it runs like a champ and I am out of ideas. There have been water circulating noises in the dash the last 20K mile but nothing leaking and I have heat....Any ideas?

Thanks Indy... One thing I noticed after starting the car cold with reservoir cap off is little or no circulation after car has reached operating temp...maybe I will get lucky and it will be a waterpump issue.

I started a thread a long time ago asking if anyone knew how to check or measure the flow/output of the waterpump and nobody replied other than to ask why I needed to know such a thing. I just read an article in Hemmings about aftermarket cooling systems and it stated that some of todays cars are designed to run as high as 245 to 265 degrees and as long as the recovery tank is full it works fine. Auroras run in this range in weather above 76 degrees and it makes me nervous. These are not summertime cars when you live in the Mojave desert as I do. So I'm thinking of having an all aluminum radiator built that's a full two-row(2.25") deep. From what I've read and the techs I've talked to, this should allow the fans and thermostat to work properly like in other cars. The rad is a heat sink and for a car that doesn't have an open grille, I think GM under spec'd it just like the A/C compressor.

How is your water pump belt? If your head gaskets or gasket was blown, there may be oil in the coolant. It may be your pump, but if your radiator gets hot after your engine warms up, the pump and thermostat are doing something. And are your fans coming on at the right temperature. I think its 220.

Isn't it coolant in your oil?