timer pointer, piston stop, excessive play?

[WestPoint]

1986 Evinrude 90HP v4 crossflow

OEM manual says to set pointer, rotate flywheel cw about 1-1/2 in. past TDC mark, insert piston stop in #1, hold flywheel so cylinder is against stop, and mark spot. My question is, how much pressure should I use to hold flywheel against stop before marking location? I noticed if I put alot of pressure on flywheel in ccw direction, I can get it to move an additional 1/2 tooth.

Manual then says to continue rotating flywleel in cw direction until you feel piston contact stop again, and mark 2nd spot. When doing this, I noticed putting additional pressure on flywheel does not result in any more movement.

I've read somewhere that you should check for excessive play using a piston stop. What is considered excessive for this engine, and in which direction should I be checking it, given that when going cw I get no play, but going ccw I get 1/2 tooth play?

 

[R.Johnson]

Re: timer pointer, piston stop, excessive play?

You bring the piston up to the stop tool, and that is it. You don't use any force at all.

 

[WestPoint]

Re: timer pointer, piston stop, excessive play?

Got it- thanks. But what about checking for excessive play. On some forum, may have been this one, the poster said to hold flywheel and with a screw driver or other tool, push against piston and check for play. They said there should be hardly any. Can one use a piston stop instead, and try moving flywheel to check for play?

 

[R.Johnson]

Re: timer pointer, piston stop, excessive play?

That test is for worn wrist pins', or bearings', not likely on your engine. You don't use a stop tool for that test.

 

[WestPoint]

Re: timer pointer, piston stop, excessive play?

OK- much thanks for the advice.

 

[CharlieB]

Re: timer pointer, piston stop, excessive play?

The piston stop tool and method is simple a very quick and accurate means of setting TDC.

Pistons are designed and constructed to push against AIR, not steel.

Forceably attempting to turn the motor against a piston stop is a good way to ensure that you WILL BE taking that engine apart to replace the damaged piston.