Umrswimr

Driving home from work I noticed the "Check guages" warning light came on. The analog coolant temp guage was just over the 260 degree mark. The digital guage was at 245 and climbing. Pulled over and coolant was coming out of the surge tank.

I let it cool down and opted to make a run for home (2 minutes away).

When I got home, the surge tank cap had blown completely off.

Checked the fans- both are running, check the electric WP- it's running too.

After it cooled off, I added almost an entire gallon of coolant to the top tank and restarted it.... And the temps immediately skyrocketed.

What am I looking at here? Siezed thermostat?

aminnich

When you added a gallon did you then purge the air thru the bleeder screw? It sounds more like a water pump not pumping as the initilal cause. Any white smoke out the exhaust?

pkazsr

Pump or thermostat, replace thermostat with fail-open type, then if it overheats and the heater hoses are cool, replace the pump.

CStewTAMU

Where are these bleeder screws everyone talks about? I have heard them mentioned many times on threads like this, but no one has ever said where they are located.

TIA

BADDUCK

My guess is water pump. Look on the thermostat housing.

Umrswimr

Ok, looks like the radiator is toast. There appears to be a nice crack running down the passenger-side tank. If the thermostat was stuck closed, the radiator certainly wouldn't have cracked, so I'm betting that the radiator is the root cause.

It still could be the pump, but I doubt it since I could hear (and feel) it spinning. Unless the impeller siezed and the motor managed the shear the shaft, I think it's probably fine. I'll check it when I pull the radiator.

Time to go shopping.

BADDUCK

Glad you found it. Now we know where the coolant went!

aminnich

Right on the t/stat housing on your 95. Only one bleeder screw, earlier LT1s had two of them. If you do not bleed the air it is positively going to overheat. Fill system, wrap a rag around the bleeder, leave cap off, start motor, bleed it, keep it running until t/stat opens and bleed it once or twice more. Obviously adding A/F as necessary during the process and keeping any A/F from running down on the optispark.
You will just love the 3 little screws on each side of the shroud when you go to pull the radiator (7mm i believe). Top and bottom are relatively easy (remove the horns to get to the bottom one), middle one is real PITA. Hope this helps.