1962 40 hp powerhead: pistons loose

[Intermediate Mariner]

Hello Everyone.
Hopefully some of you have probably seen this before or know about it.
In performing a variety of repairs I have removed powerhead and cylinder head. I had the PH on the bench with the top of the pistons exposed and noticed that the pistons are pretty darn loose!

I mean I know there should be SOME clearance between the rings and cylinder wall (the book shows 0.005) but geeze, I can wiggle them good! This is my first outboard overhaul but I remember automotive pistons being in there pretty tight and having no wiggle room at all!

Should the pistons be in there tight and immoveable? Or am I in for ring replacement (and if so, should I replace bearings if they look good or just rings and go)? Also, will I need ring compressor or can I install by hand?

PS: Motor IS NOT locked up and feels pretty smooth and turns easy, maybe too easy... I can grab the top of crankshaft with my hand and turn it effortlessly, should it be that easy to turn?

Thanks a Million!

Shawn

 

[F_R]

Re: 1962 40 hp powerhead: pistons loose

Those pistons are designed with a considerable amount of taper. The clearance is measured at the skirt. The head end flops back and forth a lot--as you have discovered. Actually, assuming it has good compression, it is a good sign when they flop around. It means the rings aren't stuck in the grooves.

Every bearing in the powerhead is a roller bearing, unlike the plain bearings in a car engine. Not only that, there is no camshaft or valve train. That is why the shaft turns so easy. And also why it can run at wide open throttle all day with very little lubrication.

It is hard for a car mechanic to fix outboards. And car mechanics are the first to admit that. They are just so----different.

 

[Intermediate Mariner]

Re: 1962 40 hp powerhead: pistons loose

Glad to see you on duty this morning FR!
So just let it go then? Just in case for future ref can I always remove the pistons from the powerhead at a later date while on the boat (by pulling intake and crank case) or will I have to pull the powerhead again?

Thanks

 

[Intermediate Mariner]

Re: 1962 40 hp powerhead: pistons loose

One other thing: when I pulled the cylinder head I did notice some metal shavings on top of one of the pistons but the were fairly small. Also cyl walls feel smooth.

 

[F_R]

Re: 1962 40 hp powerhead: pistons loose

Piston removal requires complete powerhead teardown. They are the last thing to come out and the first thing to go back in.

I don't know what to tell you about the metal shavings because I don't know where they came from. But not normal.