Thanks for the advice. However here is what has happened and I am sort of stumped. I ran the engine with the car on jack stands and level as a flush procedure; then installed a new thermostat {Delco # 10135627 131-51}, ran the engine 3 times with the pressure cap off the surge tank and did observe the jetting of air and coolant out the hose below the neck. I never left the coolant temp read greater than 195 Deg. F. I then allowed the engine to completely cool. No leaks, etc. The next day I put on the pressure cap, and took the car around the block at slow speed until the temp came up to 195 deg F or so; I also watched the level in the recovery tank and filled it to the hot mark. Anyway, normally in the past while driving I could observe the coolant temp get to about 195 deg. F to 200 deg F or so and then drop[indicating the thermostat opening]. However now the temperature rose slow and steady and got to 215 deg, F. without ever showing a drop - indicating the thermostat likely did not open?. So I pulled the car into the garage and allowed it to cool overnight. To my surprise, today the coolant level was still at the "hot" mark in the recovery tank. I know the thermostat is in properly. I called the dealer to verify the Delco number and it is for the LT5 engine; however there was no info on the temp range. He suggested it might be sticking. I wish I had tested it first in boiling water but didn't. As you know it is a pain to drain and open the thermostat housing again but I don't feel comfortable just driving it until I can get some advice from anyone having experienced this. Does anyone know if the Delco #'s are correct?
I appreciate any and all thoughts...
