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15hp rebuild reuse or replace piston rods

T

tomf

Regular Contributor
"Hi all,

moving along with

"Hi all,

moving along with my "15hp Rebuild Challenge" - I've sourced some replacement pistons from my local salvage shop (back story here: http://www.marineengine.com/discus/messages/12479/293199.shtml).

The "new" pistons come with their own connecting rods, caps & bearings included, so my question is:

Should I

a) just use the rods already on the replacement pistons

or

b) use my original rods & crank-end needle bearings, and pop the new pistons onto these?

TY once again!

Tom"
 
"Thx, that's what I was th

"Thx, that's what I was thinking - save the trouble of messing with the pin and piston-end bearings...

Any thoughts on which set of needle bearings to pick for the cap - those matched to the rod or crank? Or does it make any difference?"
 
thats why you should use the o

thats why you should use the old rods and bearing they are already matched to the crank both sets are used so why introduce a possible problem if the old ones are not scuffed.
 
"Good argument also... however

"Good argument also... however, in that case I should use everything from the old set except the actual piston, right? In other words, keep the old rod, piston pin, and needle bearings at both ends, since these are all matched in use.

The pin from one piston should fit another without problems, correct?"
 
the new stuff is used not in t

the new stuff is used not in the box new . just swap pistons why look for trouble.
 
"Honestly, I've sanded and

"Honestly, I've sanded and reused worse slugs than that; and they worked just fine.

Jeff"
 
"Thanks for all the input, guy

"Thanks for all the input, guys. Another reason I picked up a new set of pistons is that at least one of the originals was clearly under spec for piston clearance. Pops is correct in that the "new" pistons & rods are salvage parts; however they are noticeably cleaner than the originals.

At the moment I'm leaning towards using the "new" rods along with the "new" pistons, primarily because the original rods have some wear marks on the thrust side of the bearing surface edge - not much but enough to make me lose some confidence in them. Hopefully the fact that they're not mated to the crank won't cause problems."
 
"Any wear mark is too much her

"Any wear mark is too much here, and the same is true for the crank. As long as the rods and bearings are the right ones for the engine you should not have a problem. Bearings and cranks are not mated to each other like rods and bearing caps."
 
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