Well guys, I'm looking for confirmation of my fears. 96 Express 5.0l Vortec. Was taking a long time to warm up (even in warm weather). Added to that high temp (230) when passing. Was hoping the thermostat had failed. Replaced that plus belt and hoses (123k miles) since it was due. New prestone (green not dexcool). Now the test drive. Temp climbs rapidly to 200 and stabilized, kool. Drove for about 30 minutes steady
200. Pulled to a stop and did 0-60 max throttle. Temp climbed rapidly to
230. Let off the throttle and the temp climbed up to 230, then dropped rapidly to 180 then back to 200. 20 more minutes normal driving 200 degrees. Here's the final chapter. When I pulled in the driveway i checked the coolant (after venting pressure). Level good, but it was bubbly. Not quite foamy, with some kind of residue (not oil). I'm guessing I've got a leaking head gasket. Comments? Am I right? KenG