[trendsetter240]

I picked up a 1997 Evinrude 70 HP. The PO said that the top cylinder had some grooves in it and he didn't want to rebuild.

I popped off the head and had a look. I found that there was indeed some minor grooves in the top cylinder. There was tons of carbon buildup but the piston looked ok. The rings are still intact though one might be sticking.

The other two cylinders look fine, however. The middle cylinder head has some pitting in it. (see picture below). But the cylinder looks perfect.

What would be your advice on this motor: Should I tear it right down and hone/rebore, new pistons and rings and have the head polished?

Or would it be okay to leave until next season? Maybe just have the head machined for this season?

Any advice much appreciated.

[R.Johnson]

Look's like something loose in there, probably a broken ring,

[oldrudedude]

Did you do a compression test? What numbers did you get?

[trendsetter240]

No i didn't do a compression test. It was a spur of the moment buy. The guy only wanted 200 bucks for it and it's in like new condition apart from the problems mentioned above. (it also came with new controls, cables and oil tank)

Do you think I should put the head back on and test the compression?

At this point I'm leaning towards a complete tear down and rebuild.

[trendsetter240]

Ok. I put the head back on and tested the compression:

#1 = 55PSI
#2 = 110PSI
#3 = 115PSI

Looks like it's time for a rebuild.

Any advice on what will need to be done with the cylinder head shown in the pic in my first post? Can it be honed to remove the pitting or will i need a new one

[bktheking]

The pic was of the top of the piston, doesn't show the sidewall of the cylinder so hard to say.

[trendsetter240]

Originally Posted by bktheking

The pic was of the top of the piston, doesn't show the sidewall of the cylinder so hard to say.

Sorry, I went for a close up picture and I guess it's hard to tell where it is.

The picture is of the cylinder head after I removed it from the block. The image is zoomed in on the #2 section of the head. The hole you see in the middle is the spark plug hole from the inside.

Here is the full picture of the head but it's hard to see the pitting from this distance.

[R.Johnson]

As I said, something has come apart. I doubt if Sea Foam will fix that.

[trendsetter240]

Originally Posted by R.Johnson

As I said, something has come apart. I doubt if Sea Foam will fix that.

You're right. I am going to be rebuilding it. I've already started pulling apart the powerhead.

My question still is what needs to be done with the pits in the cylinder head as shown in the pictures?

[bktheking]

Originally Posted by trendsetter240

Sorry, I went for a close up picture and I guess it's hard to tell where it is.

The picture is of the cylinder head after I removed it from the block. The image is zoomed in on the #2 section of the head. The hole you see in the middle is the spark plug hole from the inside.

Here is the full picture of the head but it's hard to see the pitting from this distance.

OK, so that was the head, duh im slow. The motor has to come apart to see what is going on, as rjohnson said, broken ring maybe. You could pull the side covers off of it to get somewhat of look at the rings but it won't show cylinder damage if a ring did indeed break. Get yourself a good manual and start wrenching away until you find out how bad it is.

[bktheking]

Originally Posted by trendsetter240

You're right. I am going to be rebuilding it. I've already started pulling apart the powerhead.

My question still is what needs to be done with the pits in the cylinder head as shown in the pictures?

Plan on finding yourself a used cylinder head for that motor. Now you can rotate the flywheel and check the walls for bad scratches and pieces of ring, you may be getting into some $$$ here.