Evinrude compression

[harley-fixer]

I have 1957 Evinrude 5.5 fisherman. 75# compression on 1 cylinder. 0 on the other. What i looking for?

[fisherman6]

The first thing I would check is if both pistons are moving. Pull the spark plugs out and have a look while you rotate the flywheel. If both pistons are moving and compression is 0 on one cylinder, it could be a blown or leaking head gasket. Check the head bolt torque. Loose head bolts could be making the head gasket leak. If it still checks out, remove the bypass cover on the suspect cylinder and have a look at the rings. That could be stuck or broken. Cylinder badly scored, etc. I would try those things first and report back with your findings. The 75psi on the one good cylinder is pretty good compression for a 5.5.
-Ben

OldJohnnyRude on YouTube

[frankr]

Agree with what Ben just wrote. But Zero compression, like none at all, pretty much indicates the piston isn’t moving or is broken. Or the head gasket is blown, not just leaking. No bypass covers on a 5.5. Stick a screwdriver in the spark plug hole to see if the piston is moving. If it is, off with the head for a looksee.

[fisherman6]

Frank is right. No bypass covers on a 5.5. I forgot about that. 🙄
I agree that 0 compression is most likely a piston that has freed itself from the crank somehow or has a piece missing. If the piston moves pull the cylinder head and have a look. Excellent advice Frank. 😉
-Ben

OldJohnnyRude on YouTube

[crosbyman]

Ben .. check your in box messages you are OK’d to access a file on dropbox

Joining AOMCI has priviledges 🙂

[Mumbles]

If it’s the bottom cylinder reading 0, it’s commonly caused by water getting in thru the lower seal causing the motor to throw a rod. That’s worse case scenario so hopefully it’s just a head gasket.

[harley-fixer]

It is the bottom cylinder that has 0 compression. Piston isn’t moving. Hope I can repair without spending a fortune.

[fisherman6]

If it’s just the rod or even the rod and piston, there are LOTS of parts out there. I have 3 5.5s with issues and I’m going to try to make 1 good one out of them. Parts motors are all over. You may also find a good powerhead for a reasonable price and just swap it out.
-Ben

OldJohnnyRude on YouTube

[david-bartlett]

Bottom piston not moving is not good news. A used replacement power head is the way I would go. It will be cheaper and easier than repairing yours if it is even salvageable.

Put a want ad on the board. They made a ton of them and should be easy to find.

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