Cooling mystery????????

[lgrant]

96 Aurora - 172,000 miles. Started getting spikes in engine temp on road at 70 mph. No "message" shutdowns. Inspection showed leaking coolant from the assembly on waterpump side of engine (the rubber gaskets had deteriated). Had non-dealer radiator shop fix. Put in new pump and stat also. When they reassembled, car ran too hot to drive. Shop thought it was either a bad stat (that is the way it acted) or an air pocket (I wasn't present on the first filling of fluid but I asssume the engine was cold). They drained, changed out the new stat and refilled trying to avoid any air pockets. Engine was still pretty hot when it was refilled. There was some slight improvement but, in reality, the car was still undriveable - had to drive below 40 mph and got a few "Engine hot . . . A/C off" messages and two "shut down engine now" messages. With slow driving, the cooling has improved (the work was done 4 days ago) but occasionally, I get a quick spike in engine temp which can happen at any speed above 20 mph. Sometimes it gets to the first message mentioned above but most times it comes back down on its own without having to pull over and shut it down. It is most reliable in the morning after it has completely cooled overnight. As the day progress and the engine goes through a few heating and cooling cycles, the spikes are more likely.

Anybody got a clue? Other threads about flushing, etc. have not mentioned any air pocket problems. If you didn't know better, you would guess that it is a thermostat that is occasionally sticking. Don't believe that is it.

My theory is that the original spikes were from air entering the system at the leaking gaskets and that the post fix spikes are resulting from a botched fix with a small leak that is letting air in over the heating/cooling cycles and then purging overnight. All theories welcome.

[zimaad]

Are you sure the waterpump is working correctly? Hmmm...maybe the shop left a socket in a coolant hose!

[dred98]

Did they put in the same kind of anti-freeze?
If they mixed it up the combination of dexcool and "regular" antifreeze could mess up the system.

[dwalmop]

Definately sounds like air in the system. The question is, how is air getting in the system if it was refilled and bled correctly? Hopefully, there is not a bad head gasket or something blowing hot air from the combustion chamber into your coolant.

[Retro-D]

Problem sounds just like a Cadillac I used to own. Turned out to be a bad head gasket. Check for exhaust smell in the recovery tank...phooey!

Good Luck,

RD

[dwalmop]

an easy way to check to see if the head gasket is bad is to start it up, and look for air bubbles in the recovery tank. I would think the shop you brought it to would have caught that, though. But give it a try, it will only take you 2 minutes and you won't get dirty.

[Indy8]

Thermostat installed backwards?

[Isnibs]

Cooling fans, intermittent failure?

[lgrant]

It has been determined that it is the infamous head bolt/head gasket problem. Unless someone has got a fix that I haven't stumble across, that turns out to be a death sentence for this Aurora.

I tried the K&W block sealer (twice) but there was no improvement.

Thanks to everyone who tried to help.
Larry

[JTrujillo86]

What do you mean a "death sentence for this Aurora"? Are you gonna get rid of it now?

Jeremy

[lgrant]

Originally Posted by JTrujillo86

What do you mean a "death sentence for this Aurora"? Are you gonna get rid of it now?

Jeremy

Either I can drive it or I get rid of it. So far there hasn't been much encouragement for being able to drive it.

If you have an idea, I would love to hear it.

Thanks, Larry

[sundown]

I had air in the radiator because the vent hose from the radiator to the overflow tank was clogged at the barb on the tank. CLeaned it with a drill bit.