Compression Test Questions

[imelmo]

Got everything set up to do the compression test on ZMBYKLR today. Teated one of the front cylinders first for a baseline and it read a little under 400psi. Hooked up to do the cylinder that had the broken rocker arms and it jumped up to 500ish psi. Pulled the tester out, turned it over, and realized the stand pipe was pumping oil still (even though I drained it) and must've gone in the cylinder thru the glow plug hole. So two questions.


First, can I remove the standpipe while doing the compression test so it's not pumping oil out into the cylinders?

And two, what's a good way to get the oil out of the cylinders? It appears to only be in the rear two. I'm thinking I'll just try and rig something like a straw up to a shop vac and suck it out the glow plug hole unless there's a better/easier way.

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[6.0 Tech]

Pulling the stand pipe should be ok. As for clearing out the cylinders, cranking it over with a shop rag over the holes should pump it out ok. Kinda like doing injectors on a 7.3

 

[imelmo]

Cool, thanks.

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[Downey]

How are you. Checking compression we always use the glow plug hole.

 

[golfer]

How are you. Checking compression we always use the glow plug hole.

yeah..what he said...

also, since it sounds like you're doing this during (or after?) having the injectors out...

you're going to have some oil on the piston(s) which are going to make your compression numbers 100% unreliable.

regardless of how much oil you suck off the piston/out of the bowl...

until the engine starts/runs, and burns off that oil/fuel on the piston, you're numbers aren't going to tell you anything reliable.