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Over Revved and no compression


zdude1967

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I am heading to Harbor Freight now for the compression tester.

If I do find it is a bent valve should I have concerns about any damage to the bottom end.

If so is there a way to check it for damage. I am not sure how many miles are even on this engine, it did run weel prior to the over rev.

Glenn

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Glenn,

When I conduct a differential compression test I put the piston in the cylinder to be checked at TDC, then place the transmission in 1st gear (with the e-brake on and the wheels chocked). If you have a helper. have them sit in the car with their foot on the brake.

I then open the valve on the tester to allow 80 pounds into the cylinder. 78 pounds is the magic hold number, but if the cylinder holds within 10% (72 pounds), you have a good/OK cylinder. Below 72 pounds listen to the exhaust, carb or crankcase breather for escaping air. Based on where air is escaping from will tell you where you have a problem, i.e air at the carb is the intake valve, air at the exhaust is the exhaust valve and air at the breather are the rings. If you don't hear air from any of those and can not maintain at least 72 pounds of pressure, spray soapy water around the head gasket.

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