I have a 94 Grand AM 3.1 and I am getting temp spikes.
I will be driving along and the temp will shoot up very fast, and then stay
up around the red for several seconds, then drop very quickly back to around
1/4 on the guage.
Originally it was thought that it was just low on coolant, so my garage bled
the cooling system, and topped it up. This worked for a short while. Then
the problem returned.
The garage also ran a pressure test, and said it didn't look like there was
a leak in the system. The thermostat, and water pump were replaced, and this
seemed to fix the problem for about 2 weeks, but now the problem has
returned again. It is losing coolant somewhere, but it doesn't look like it
is going into the oil. And it is not losing fluid when I am parked.
Also I can here a loud rushing of water or gurgling noise that sounds like
it coming from right behind the dash. In addition when the temp does go up,
I can usually put the car in neutral and rev tha gas, and it seems to get
the circulation going and the temp drops to normal.
I had a similar problem before and it was the intake manifold, but there was
coolant leaking in the oil, and the temp was rising gradually and staying
up. This time the temp is spiking quickly and dropping quicky after a few
seconds, and like I said, no signs of coolant mixing with the oil.
I never did have the entire system flushed out, I think they just ran it and
let the air pockets come out. I am wondering if maybe there is a large
pocket somewhere perhaps in the block itself that is not being flushed out.
If anyone has any suggestions of what to check for next it would be much