Mercruiser 140 ID

[38special]

I bought a used Mercruiser 140 and the S/N tag is missing. Can i ID the build date of this engine by the numbers stamped in the pad by the distributor or the casting numbers on the side of the block?

Unlike my other 140 with the recessed D shape in the top's of the pistons this one has flat top's with notch's for the valves.

 

[Bondo]

Re: Mercruiser 140 ID

Ayuh,... There's not alota resources out there for that,...
What's the Problem anyways,..?? What are you trying to do,..??

 

[38special]

Re: Mercruiser 140 ID

It needs a piston Bond-o. There's about 1'' 3/4 length just above the ring missing. The cylinder looks un damaged. If i knew what year it is would help in finding a piston. I'm going to take that one piston and rod out today. Does Mercruiser or GM have a part number inside of the pistons? There is no numbers or writing on the tops of these pistons.

 

[Bondo]

Re: Mercruiser 140 ID

Ayuh,.. there Should be a Part # on the piston...

Sounds like it ran Lean,+ Detonated itself to death...
I'd pull All the pistons for a good cleaning,+ Inspection...

 

[fixb52s]

Re: Mercruiser 140 ID

Hate to say this, but the description of the piston leads me to believe you have a 2.5L engine. The best way to check is measure the bore. 4.0" inches for the 3.0L and 3.875" for the 2.5L. If you can use a 2.5L piston, let me know. I have 4 good ones with rods I pulled out of a block last week.

I bought the short block last week (with the same block casting number as my 3.0, 2770087) and found out it was indeed a 2.5. I am getting it bored out to 4.0" and will be using my 3.0 crank, rods, cam and new pistons to make it a 3.0.

I found out that they use the same block casting for both engines in the 80s. So going by that will not tell you much. As for the number stamped by the distributor, I have not found out any info on that yet.

 

[38special]

Re: Mercruiser 140 ID

Ayuh,.. there Should be a Part # on the piston...

Sounds like it ran Lean,+ Detonated itself to death...
I'd pull All the pistons for a good cleaning,+ Inspection...

Agreed. I just got the piston out and on the side is a circle with what looks like an SL inside the circle and to the right of that CLAIM or CLAIH. I took the second ring off the piston and used the piston to shove it back down into the cylinder then measured the gap. Gap was .035, i'm sure thats to much and these pistons are .030 already. The cylinder looks pretty good but i think that gap is way to much.

 

[38special]

Re: Mercruiser 140 ID

Hate to say this, but the description of the piston leads me to believe you have a 2.5L engine.

I just checked it with my caliper's and the bore is 1/32 over 4''. Thanks for the offer on the parts.

 

[38special]

Re: Mercruiser 140 ID

Just got back from the machine shop and the dial bore gage only showed .001 wear on the cylinder with the bad piston. The pistons are silvolite. He has 4 used but new looking forged pistons for $10.00 each. The pin dia. is the same and compression hight is the same.

He had several sets and were high doller new. The one set would be noisy and the other would run quiet for forged pistons so i bought them.