[spiderrick]

I have a not-yet-running 84 Spider project in the garage. The car came with a spare engine. The engine that is IN the car went through an electrical fire but shows no obvious signs of damage. The spare engine came out of a donor car that might have been a bit beaten. I am getting to the point where I need to decide if I should stay with the engine that is in the car (and may be damaged due to the fire) or switch to the spare engine. I would like to do a compression test on both engines. I just read that the compression test should be done on a hot engine but at this point there is no way I am even close to being able to start this engine. Do I have to get the engine cranking to obtain useful compression info? Should I assume that the engine in the car was damaged (or NOT damaged) from the electrical fire? The fire got hot enough to warp the hood and bubble the paint on the passenger side fender. The wiring harness under the hood is mostly cooked so cranking the engine over might be tricky.
Thanks Much,
Rick
Southern, NH

 

[ghnl]

Unless you see obviously melted metal the engine itself is unlikely to be damaged by the fire. But the externals - wiring, fuel supply, etc will probably be damaged.

 

[ghnl]

One other thought (they tend to occur randomly...) is that you can do a leak down test. Basically you position the piston at TDC with the valves closed then pressurize the cylinder with air via the spark plug hole. You can then listen for air leaks. Be careful though as the air pressure can suddenly make the engine turn!

 

[spiderrick]

Thanks Much! What about a hydraulic (rather than air) pressure test? Because the hydraulic oil is not compressible, any loss of oil due to leakage would result in a decline in pressure which could be seen on a gage? I might try this.

BUT: I discovered a new problem: The transmission bell housing is broken near where the starter mounts. I need to get the transmission out so I can replace it with the spare that came with the car. New post to follow . . . .