Piston getting replaced...looks a touch different

[Brock.Ward]

I have a 1985 115 vro outboard envinrude, bought it with a blown piston, got a new one from an identical used motor but looks a little different, size, everything matches, even numbers on the pistons but arm is a little different, does this matter, if numbers match should I be ok? I am assuming its because it may be a refurbished piston or rebuilt idk. Any help is appreciated.

 

[rothfm]

A bit more to it than that. Bores and pistons have to be measured carefully(new and used). There's several specs on the cylinder walls, pistons and ring slots that are critical. By "blown piston", what do you mean?

If the piston is damaged, then most likely the bore is also, or at minimum is out of spec. Then there is the question of why was it damaged? There is a underlying cause that needs to be investigated also. Yes, rods could have superceeded to new pn's. You will need to follow the OEM manual to properly correct that Powerhead.

Maybe this is all known to you, not sure from your post. I just completed a 115 Rebuild with Brand new pistons, rings etc..., and have 2 successful test runs thus far. Post more, If I can help I will!

 

[Brock.Ward]

Thanks a ton buddy! I am fairly new to this rebuild but my buddy is a mechanic. I do understand weight and boring it out but here is my situation. I got this boat cheap due to the engine, I have rebuilt engines and am not looking to put a ton of time and more important money into this engine. It was almost completely ripped apart when we got it. This guy beat the crap out of this engine, he stated he would take it about 40 miles full throttle on lake michigan, so my thoughts are he blew a piston due to a dirty carb or something to that matter running it full throttle at that distance, and you should never run outboard full throttle anyways. The other pistons look great, the walls look good even the blown one looks good, I was gonna clean it out the best I can and install the new piston, throw it back together and run with it, if it last a year or the summer i'll be happy. I have gotten quotes on rebuilts for 1K-1500 on this engine and I dont want to put much if any money into this engine if I can go buy a used 75-80hp which is more than enough for a 16ft four winns for the same price if not a bit less on craigslist. So my plan was to take the time to throw the piston in, put it back together and hope it gets me through a summer. I enjoy doing it so i dont mind the time...thanks again for your help. Also can you use marine RTV for gaskets or should I be buying a gasket set. any recommendations on where I can get quality cheap parts for this?

 

[Brock.Ward]

Looks like gasket sets are a bit too, any silicone you can use for these engines? Or a gasket maker? Otherwise recommendations on where I can buy the sets?

 

[emdsapmgr]

Pistons that have the same part number are the same and should all weigh the same. You can use it. If the rod does not match the configuration and part number of the others, that could be a problem, unless it is a supercession part number from the original. If the rod is a direct supercession, it should weight the same and perform as the other 3. I'd check with a Bombardier dealer or call their customer service hotline: 262-884-5993.