455 low compression

[Captain Bart]

Engine internals look fine. Clean piston, rings, and cylinder, no scoring, BUT a compression test shows 50 psi? Where is the compression leaking off?

 

[Stihl 99]

I wonder if it would be decomp valve, bearing seals, or cylinder gasket?

 

[Donuts]

That's a head-scratcher, with clean internals, I'd check the crank seals or base gasket next, it could be leaking there, it is also worth pressure testing the case to track it down

 

[Captain Bart]

Thanks for the equally curious wisdom, as it is. Compression is measured at TDC. The only way to bleeds out is past the rings........bearings don't seal. Crank seals seal. Turns out the little impulse hose was dried out, cracked, not there.

Saw repaired. Thread closed. Happy 4th of July!!