Evinrude big twin 40353D overheated

[sms986]

So I've been in the process of moving to a new state for a few months now, and over the duration of that few months my boat has been in the hands of a good friend. He told me in October that the boat overheated and he had a hard time getting it back. I just got the boat down to my new house. The water pump was destroyed, so I replaced it. Decided I'd take it down to the **** and see what what was going on, being that the damage was already done . It only ran on one cylinder. Tore of the head, exhaust cover, and bypass covers. Both cylinders are scored and the pistons are as well. Looks like I get to rebuild it again. I'm going to check to see if any of the mating surfaces are warped and have the cylinders cleaned up. I'd like to replace as little as possible, being that I already rebuild this motor two years ago. Going to do wrist pins, oversized pistons and rings, and obviously new gaskets. Anything else I should definitely replace?
also, where can I find a good set of overbore pistons for a decent price? Marine engine has them for $100 a piece, but I'd rather not spend that much being that a pair of new STD bore pistons with rings, pins, and clips can be had for $70.

 

[racerone]

Hunting on EBAY will get you the parts at the price you like.

 

[sms986]

Yeah, I've been on eBay all morning digging around. The best way I've found to get parts on eBay is with the part number, but I don't know/can't find the part number for overbore pistons.

 

[racerone]

I think I have a good set of used O/S pistons.------But shipping is a problem------The part # for O/S pistons may have changed a few times.-----Keep digging and you will find a set.

 

[sms986]

What's the problem with shipping?
I am interested..

 

[racerone]

Contact a shop---evinrudeparts.ca.--------In Ontario.----They may be able to help you.

 

[racerone]

Lots of O/S pistons on EBAY for that engine.

 

[F_R]

Yeah, I've been on eBay all morning digging around. The best way I've found to get parts on eBay is with the part number, but I don't know/can't find the part number for overbore pistons.

Latest part number I have for .030 is 384715 piston and 385811 ring set.. I believe that is the pressure-back piston/rings type (?),

 

[sms986]

I believe you all when you say they are easy to find, but for me the only way to match these pistons to others online is to mic them. I don't have any idea how to find cross reference info or anything. I guess that was my question. I need to know where I can pay numbers that match. For example, F_R you gave me a piston part number. First thing that popped up on Amazon was a $25 piston. I read through it and it said '71-'76. It looks the same, but without confirmation I can't judge that the '71-'76 includes '63. Anyway, if anyone can give me an idea as to where to go for cross-referencing, I'll start there.

 

[racerone]

The newer " pressure back " 2 ring piston was a direct factory replacement for your motor !!----383069 is a 0.025" O/S piston.------Find a deal for that and rings on E-BAY

 

[F_R]

The source I used gives the current part number as of the date it was published (1976). It does not tell how the number progressed or changed through the years. To get that information, you have to wade through the master parts price books through the years.

 

[sms986]

Thanks!

 

[sms986]

After much deliberation, I decided to take the risk of buying a used case. At the end of the day, the cost was much less and I feel more comfortable being at STD. Bore. I picked up a case from a '67 Johnson 40. My head is warped, so I'm going to try the old sandpaper on glass trick, which I've had success with before. For those in the future who will be seeking future advise, here's what I do. I soak the head in gasoline for an hour and tape a 12x18" 220 grit sheet of sandpaper to a flat sheet of glass. I take a plastic wire wheel and knock off as much gasket material as I can. I'll make a few passes on the sheet, rotating the head 90 degrees each pass, until most of the surface is fresh and shiny. It's important to let the weight of the head create the normal force. Don't push down on it. I'll them switch to 400 grit and make a few more passes until the entire surface is fresh and shiny. Check with a straightedge them finish of with 800 grit until all deep scratches are worked out. Works like a charm.

I do need to get gasket maker for the case. Can't remember what the omc replacement was. Anyone know what it is and where to get it locally?

 

[racerone]

Why would you soak the head in gasoline for an hour ?----I want to know the practical reason .

 

[sms986]

It really, really softens and breaks up gasket material as well as any gunk. Makes things much easier than how some people do it with a razor or a wire brush.