No . . . gasoline engine
1st generation GMC Canyon
The general rule of thumb regarding compression on an engine in good shape at roughly sea level is 20 X the compression ratio. Drops a bit with wear and elevation.
You say the other cylinders are good. What do you mean by good?
I ran a compression check on my Lincoln at 275k miles while replacing plugs (4.6 DOHC) and it still carried 180 a cylinder.
The others run in the upper 100s, at least 160 psi, never had any problem with misfiring on any cylinders except for #1.
Compression is decent at 160 so I agree with the partial repair.
Take the suggestion from expert mechanic, In few case it dangerous .
Itās quite possible thereās buildup around the rings as the car sat for quite a while before I bought it about a year ago. I think it might be possible the dent on the crown of the piston moved the ring out of place so Iāll be checking for that as well.
perhaps I am confused here, so help me understand if I am, but:
When did you check compression on this engine? Before you removed the old head with bent valves?
if you checked compression with bent valves, that is why compression was low.
or did you check compression with the new head installed? and if so, why is it back off now?
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I checked compression with the new head on, but I used an old gasket and old bolts just so I didnāt waste the new ones I have torquing everything down. I had to take it back off so I can install it with the new bolts and gasket.
I wouldnāt trust readings with an old gasketā¦
They definitely arenāt āfor certainā readings with a used gasket, but for the compression readings to jump so high after a wet test indicates the piston/ring problem if Iām not mistaken.
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