115hp piston rings

[danny9696]

Hi all I have my engine apart to replace #1 piston, and I wanted to replace my rings in the other cylinders but all the rings I am finding are a set of two and my OEM pistons have three, need someone?s advice on what to do!

Also along with resealing the engine is there anything else that is recommended I replace while I have her apart

Thank you all again

 

[Laddies]

Re: 115hp piston rings

You may find a dealer with a 3 ring piston but all new stock are 2 ring. They are the same weight and a direct replacement part, some 2 and 3 ring pistons do not use the same rings so check the part numbers before ordering.

 

[Chris1956]

Re: 115hp piston rings

Danny, Check the rings carefully. The two ring pistons had keystone shaped rings. The three ring pistons were rectangular rings.

I would think a dealer would have or be able to get the original rectangular rings. My '77 Merc 1500 had the rectangular rings, so that is a starting point. Hopefully they are not discontinued.

 

[Faztbullet]

Re: 115hp piston rings

All Inlines use the rectangular rings, the V-6 150's was where keystone shapes where used. The OEM part number for 3 ring set is 39-77816A12 or you can use the Promarine 3902 set. Check the cylinder good for damage before replacing piston.

 

[Chris1956]

Re: 115hp piston rings

Fast, I was sold some inline six crossflow pistons by merc that had the two keystone ring design. Merc did seem to have an issue locating replacement rings for these, for some reason.

 

[Faztbullet]

Re: 115hp piston rings

It sounds like someone sold you a aftermarket in a Merc box !! I been doing repairs for over 35 years and only keystone inline pistons I have seen was the old Dolphin and Wiseco. I would have love to get a hold of one of these to put in my "OOPS" collection !!! You dont happen to still have the part # of piston and rings,as I would order one for collection.

 

[Chris1956]

Re: 115hp piston rings

I have a couple of NOS rings laying around the garage. Let me see if they are keystone or rectangular, and whether I have the box.

BTW - The Merc dealer where I bought the 2 keystone ring pistons indicated that they were std equipment on the newer inline sixes(post '77). I obviously took him at his word.

Thanks...