Help! Cooling issues

[95aquase]

I have a 95 GP with a 3100 in it. Two days ago this started. My temp gauge in the dash would go up to around 240, then drop all the way down to about 150. I had the heat on from the vents at startup and it blew cold till it dropped down then it was hot. It did this repeatedly about 2 min in between. It did it more when it warmed up. But it does the same thing every time. I figured it was a possible tstat so i replaced it, bled the system. The problem is still there. I take off the radiator cap when the car is running and i see coolant. I rev the car up and the level drops then comes back up. What is causing this temperature fluctuation?

[Crazy K]

air gets trapped behind the t-stat on 3100 cars. I recommenc disconnecting the line that gos to the heater core (or removing the temp sensor by the tstat {or both!}) and 'backfilling' the system from there.

[GP1138]

The 3100 in particular is terrible with air in the system. When we did the top-end swap, it took like a week before the cooling system was back to normal. Keep checking to see if you need to add coolant, it sounds like there's air still in the system.

[19Cutlass94]

As long as youve got the radiator full and the overflow where it should be, eventually the air should work its way out of the system. Just make sure youve got the coolant to the level where it should be all the time, or else the problem will just get worse.

[Canada]

Easy way to bleed the system when you have the thermostat out....hold it open with a couple of asprin....air goes out, coolant hits it and they dissolve!

 

Is your intake leaking?

[GP1138]

Easy way to bleed the system when you have the thermostat out....hold it open with a couple of asprin....air goes out, coolant hits it and they dissolve!

 

That's a cool idea, I would have never thought of that!

[95aquase]

ok, update.

i changed the thermostat, did not help.

took off all the coolant lines, the one that goes from the crossover to under the intake. bone dry, top hose going into heater core, bone dry, crossover had coolant in it.

the coolant bubbles inside the resivior.

put a new radiator cap on.

did all this and the problem is still there.

any clue?

[PCGUY112887]

Did you do anything that may have started this in the first place, or did the temp gauge all of a sudden go bouncing around?

[95aquase]

just started to happen, i hadnt touched my car for over 2 months, i know it has a slight misfire. im more worried that it is a head gaset. and what sucks is that i drove to school, parked cam back to my car. and got in it to drive home and the temp went way up. it does it on the highway too.