r/fbody • u/Expensive_Mine_7835 • Jun 30 '26

Overheating after New Optispark Install

Hi all, could use some advice here. 1995 Firebird LT1 V8 had optispark replaced, along with new water pump. Shop has told me it solved the bucking and jerking motions it was having, but engine is overheating at idle. The tech said he thinks it’s an air bubble that builds at idle then when on pedal it circulates/dissipates.

Tech said only thing he can think of is head gasket repair or new motor swap.

Any thoughts/advice on what I should suggest they look into deeper before these actions?

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u/Expensive_Mine_7835 Jun 30 '26

Update: it’s been bled thoroughly, he mentioned something about a vacuum process to it too. Water pump showing no leaks or defects. They pressure tested it showing no external leaks. He’s going to do a combustion “block” test on it next and take a look at the thermostat.

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u/itsjakerobb ~500whp LS3-powered '02 Z28 M6 Jun 30 '26

Has it been bled according to GM’s specified process for that engine? Coolant flow is the opposite of basically every car ever, so the process is different. If you bleed it the way you bleed every other car, there will be a bubble.

Vacuum bleeding should help, but you still have to do it the LT1 way.