#60646

Steve:
Just a couple of quick questions. You said you’re overheating — are you actually boiling over, puking coolant? Without a thermostat, your engine should actually run cool, which affects gas mileage and does cause sludge build-up over time. I recently did my ’65 Malibu ragtop 283 SB at .030 over and ran around 250-265 degrees on it’s maiden voyage. But after 100 miles, it was down to 195 — the thermostat rating. A rebuilt engine will be tight and run hot for some miles; depends how you break it in. Don’t be a wimp — if the block has already been broken in, (i.e., is used; rebuilt or not), drive it. See what it can do.
Second, have you run any kind of cooling system cleaner through the system? A reverse flush (pressurized with the engine at operating temp — requires a machine designed to do this) may clean out any schputz that may still be in the block/head passages. That the engine shop didn’t get before the rebuild. Once you have your radiator back, do that. You won’t hurt anything.
Third, if you’re relying on a gauge to register “hot”, are you certain the gauge is accurate? And the sending unit? Easy to check.
Good luck — the S5 is on jack stands and beckons me…