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  View original topic: lifter's effect on cylinder compression?
vwvwvwvwv Fri Mar 12, 2010 4:59 pm

Can a bad lifter/lifters on a 1.9 waterboxer cause almost 0 compression in one cylinder?

Wildthings Fri Mar 12, 2010 6:05 pm

It could but probably not. If a lifter doesn't pump up at all the compression will most likely read about 20psi. If you have the lifter adjusted way too tight or for some reason the lifter doesn't purge normally it could hold the valve open, but shouldn't cause zero compression.

vwvwvwvwv Fri Mar 12, 2010 6:14 pm

thanks

?Waldo? Fri Mar 12, 2010 6:25 pm

Wildthings wrote: It could but probably not.

I agree with both parts of that. It depends on several factors. One factor would be the amount of valve overlap in the cam. Another factor is where the piston in that cylinder last was when the engine sat long enough for the pressure to normalize. For instance, if neither valve opened at all and sealed well and the piston was last stopped at TDC for that cylinder, then when checking compression, the piston would register zero. If there is no valve overlap (diesel engines) then if the intake valve is not opening at all then zero compression would result regardless of piston position. In most cases, tho, it will show some compression. A leakdown test is more conclusive.

vwvwvwvwv Fri Mar 12, 2010 6:35 pm

it's not diesel.

thanks very much!



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