cnicoll wrote:

I have a 1989 Evinrude 88hp SPL outboard.

Recently I replaced both head gaskets with low compression gaskets.
I flat sanded both heads on a granite surface plate and block sanded
the power head. They were torqued properly (18-20 ft lbs) but after my
maiden run in the ocean I checked and discovered salt deposits on both
of the heads at the head gaskets.

I am concerned I might have compromised the flatness required. I work
in a machine shop and am pretty familiar with flat sanding.

I phoned a boat shop locally and their opinion is that the heads need
to be machined and the power block may also have to be machined.

A couple of thoughts I had:

1. Perhaps the type of head gaskets I put on (Low Compression Head
Gaskets) were not the appropriate type? I thought these were simply
for using lower octane fuel.

2. The flatness was indeed compromised and machining is necessary.

3. Perhaps there is a trick that can be used to resolve the problem

If Machining is needed I can do the heads myself on a milling machine
but don't want to have to pull the power block and machine it too if
possible.

Help on this would be much appreciated. Any tricks you might know
would be great.

Thanks in Advance!

If you work in a machine shop, you should be able to check flatness of the
heads fairly easily (the recommendation to machine them means they guy asssumes
they are either not flat or not smooth. If you flat sanded them, I'd expect
they are smooth.) Same goes for the block (checking for flatness would involve
a straight rod (usually ground) and feeler gauges). I wouldn't think
machining these surfaces would improve anything if they are already flat and
smooth enough to seal.

I'm afraid I don't know about salt deposits or if whatever you see is normal
but if these deposits are uniform around the gaskets then not sure I would
assume anything flatness was an issue.