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need help with compression test readings

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eschneider

eschneider

Jedi Warrior
Offline
with all plugs removed:

cylinder 1 - 150#
cylinder 2 - 0 (nada, nil, zip)
cylinder 3 - 150#
cylinder 4 - 160#

with #1 & #3 plugs re-installed: same results

with 30wt oil down the #2 hole, I get 40# of compression.
wait 30 seconds, test again, 10#
wait another 30 seconds, re-test, nada. Zero compression.

What the heck?

I've never seen 0 compression before.....

oddly, the #2 plug looked nice and tan. No hint of oil-fouling.

sorry if this is posted in the wrong forum.....?
 
I would have guessed you had a stuck valve, but putting oil in the cylinder would have no effect in that situation. You may have blown a hole in a piston. I just can't imagine the rings are so gone that you have zero compression, but I suppose it's possible!
 
that's what I'm thinking - zero compression is unlikely bad rings, especially on a single cylinder - but the oil has me mystified.

maybe a really badly blown head gasket, and the oil was working its way through the gap?

guess I'll not give up just yet.....
 
You're right that the oil results don't make sense, but neither does zero compression. It sounds like a broken piston or valve. Maybe a cracked cylinder wall or head? It doesn't sound like a minor problem.
 
If it is overhead valves, take the rocker cover off and you should be able to see if a valve is sticking badly.
 
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