Noise in115 merc 4 cyl

" I have recently put a second

" I have recently put a second hand 1995 115 merc onto the back of a 18 foot pelin(ply boat), the previous owner had no trouble at all, (he says), the motor makes a rattleing nocking like sound at 3500rpm when the boat is on the plane and the load is off the engine a bit. It is lacking no power, and runs great. I have pulled the engine down and all the pistons are spotless, all needle rollers are there, reassbled, done carbs 3 times, checked all bolts on engine 10-20 times. been onto the head boys at merc in this country, they have herd the sound but are not much help. I am hopeing some one out there has had the same thing and has fixed it couse its srarting to drive me nutty. thanx. "

Is this reed valve noise resu

Is this reed valve noise resulting from a high vacuum in the crankcase? Two strokes are a different beast you know.

" Had a bit of luck today, on

" Had a bit of luck today, on advice from a friend who knows mercs very well I pulled the pistons out again to find that the letters stamped on the top of the piston "up" at the top and "s" at the bottom (they are the same pistons as out of a v6 S = starboard) have been hitting the top of the block, there are clear little marks on the top of the bore, (these engines dont have cyl heads). sounds very hard to beleave I know, I wouldnt have beleaved it if hadnt seen it.

I have noticed this site is dominated by omc boys so im sure you guys will love this one. "

"Greg..... Your last post brou

"Greg..... Your last post brought forth a memory. Many years ago, a new three (3) cylinder Evinrude, right out of the box, installed on a new boat at a local marina in my area, upon its very first runout simply would not run properly.

In checking the engine, everything checked out okay except that the compression seemed somewhat strange. Now, this is a brand new engine with zero hours. I removed the cylinder head to find that one piston had been installed upside down (at the factory)! OMC had always accepted my word for anything pertaining to problems, warranty, etc, but they had a little trouble believing this one.

Joe "

" Greg,

I don't underst

" Greg,

I don't understand what it is you are saying. The stamped letters on the piston are not raised, so why would they touch the cylinder head. It seems to me the entire top of the piston would be contacting the head area. As I remember it these pistons have a flat top.

I just get the feeling that there is something more to it.

Tony "