Is this engine worth changing?

Thumbtack

Petty Officer 2nd Class
Joined
Aug 3, 2007
Messages
118
Mercruiser 260 v-8.

All cylinders are up to about 170 compression except for one which is showing 105. If I put a few squirts of oil in it it gets up to 120-125 so it must be going past the rings. We haven't ran the engine yet in the water and I was wondering before we go through the process of putting everything back together should we bother with the engine. This one is a little close to call.
 

Bondo

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Apr 17, 2002
Messages
70,465
Re: Is this engine worth changing?

This one is a little close to call.

Ayuh,... Flip a coin,... It'll probably run thru the season...
 

JustJason

Vice Admiral
Joined
Aug 27, 2007
Messages
5,319
Re: Is this engine worth changing?

That oil may just be gettin shot right up your compression tester....

1. try a leakdown tester instead of the oil "trick"

2. pull the valvecover associated with that piston. Have a look at the valves to make sure they are the right height, the rockers aren't loose, rocker studs haven't pulled....
 

rbh

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Mar 21, 2009
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7,939
Re: Is this engine worth changing?

one thing I have relearned latelly is that boats that idle for a long time have a better chance of getting valve problems than ring problems.
if you fish and do not open up the engine once in a while you "could" get a chunk of carbon stuck to the valve or seat?
just a thought.
rob
 

gadget73

Petty Officer 1st Class
Joined
Jun 20, 2009
Messages
308
Re: Is this engine worth changing?

+1 on the leakdown test. It will tell you exactly where the compression is going.
 
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