115 cross flow water in cylinder!

[jeremy5780]

I picked up a 115 evinrude cross flow and was told it had water in the bottom left cylider so i tore it down and sure enough it did it appears the piston is rusted to the cylider wall and the connecting rod is rusted as well however it appears to only be surface rust. I took a rag and some wd40 and with some elbow grease the rust came off. I am wondering will i be able to do this to the crank and cylider wall and just get some new rod bearings and piston and put it back together?

 

[CharlieB]

Re: 115 cross flow water in cylinder!

That's a tough question to answer with seeing and touching the parts.

Generally rust is like a cancer, it must be cut out or the surface imperfections speed the wear on the matching surface.

Crank journals and rod bore surfaces may be polished with crocus cloth , how aggressive is determined by the depth of the rust and the clearance allowed with new bearings installed.

Cylinder surface rust may be honed lightly, but there again you must be careful not to exceed clearance with a new piston or you will end up having to bore the hole and install an oversized piston.

No doubt that you can clean it up and it will run, the real question will be for how long.

You haven't addressed how the water got into the motor, that needs to be addressed BEFORE you spend any money on parts or machine work.

 

[iwombat]

Re: 115 cross flow water in cylinder!

I really don't think I'd be running that crank unless I had it turned for oversize bearings (do those even exist?)

I'd also be replacing the lower crank bearing w/o so much as a second thought.


Either that, or take the whole mess to a machine shop and get a professional opinion.

 

[ledgefinder]

Re: 115 cross flow water in cylinder!

Short answer is you'd be better off finding another good, used powerhead than messing around with that one.

On the crank & big rod ends, the shop manual says if you can remove the watermarks with only crocus cloth, you can re-use those bearing surfaces. Problem is, the few times I've tried, I found you can only remove very minor marks that way.

The affected rings are shot. If you can clean the marks off the cylinder walls with 600 grit paper, you're good to go BUT you still need to mike the walls & pistons to see if they're any good.

Now this all applies to making a proper, seaworthy motor. If you just want to see if you can get the thing to run again - sort of as a stunt or to make a limited reliability small lake ski motor - you could have at it. Problem is you STILL need to find out why the water is getting in there in the first place. I think even the quick & dirty low-buck method is a loser here. Probably for any use, best to put your time into searching for, and throughly examining, a reasonably-priced used powerhead.

If you DO try to mess with the one you've got, I'd replace the needle bearings with new anyway (certainly don't reuse those), and don't forget you need to examine the small end bearings as well.