Cyl/Piston Wear issues-40RL71G

[PaulO]

My pistons show wear in the skirt 3.178" and 3.182"

The lower cylinder bore worst case was .005" in excess of STD 3.187".

By the time I buy OS Pistons (and I can only seem to get one of them ATM) and gaskets and bolts this could be a $500 job. Do I just stick it back together, forget about it, part it out or pursue it?

I can't justify the latter at the moment.

 

[1fishbone]

Re: Cyl/Piston Wear issues-40RL71G

I think the spec is .003 to re-bore.

If I had a pocket full of money...I'd buy a brand new motor!
If I had some money, I'd buy another motor and take my chances!

If I had the money I have right now...I'd have to rebuild it and eat beans and rice for a couple of weeks!

"What's in your wallet?"

Is that all the motor needs?
Was it running good/bad?
I'd stick with the known and avoid the unknown!
What would it cost to replace?

Just throwing some questions out there for you to decide.

 

[PaulO]

Re: Cyl/Piston Wear issues-40RL71G

There ain't that much in the pocket

I don't know what it was running like because I just picked it up. It was/is a project.

The pistons blow the budget then I have to find two. How do you know your wear until you pull down the motor and measure?

 

[1fishbone]

Re: Cyl/Piston Wear issues-40RL71G

Compression test and power issues tells me if it needs to come apart.
After I've eliminated everything else!

Quick hone, put some new rings and go!
What was the compression in each cylinder?

 

[PaulO]

Re: Cyl/Piston Wear issues-40RL71G

No.2: 109 PSI
No 1: 72 PSI

After the No.1 piston came out the oil ring was stuck in directly opposite the ring ends. A bit of a wobble and it freed up.

There is a little scoring on the piston No1 but no obvious signs of scoring in the cylinder walls.

I have run a few threads on my problems. Here is one with some pics:http://forums.iboats.com/showthread.php?t=450347

 

[PaulO]

Re: Cyl/Piston Wear issues-40RL71G

Any thoughts / similar experiences?

 

[Faztbullet]

Re: Cyl/Piston Wear issues-40RL71G

If its a restore project do it right and install pistons. If it a cheap get me on the water project,stop,part out and get a known running engine. The worn cylinder and piston skirt will make that cylinder crankcase pressure lower and if stuck back together it will have idle problems and fuel pump problems if pump is driven off that cylinder.

 

[1fishbone]

Re: Cyl/Piston Wear issues-40RL71G

After seeing those pictures...might be good for pieces/part!
That cylinder wall can't be pretty!

 

[PaulO]

Re: Cyl/Piston Wear issues-40RL71G

After getting a manual I see the piston to cylinder clearance is MAX .005" That makes my bore/s on the limit. I think a good hone will do unless someone's manual says different.

 

[54fleetwin]

Re: Cyl/Piston Wear issues-40RL71G

just remember, honing removes material.
Somebody on here uses acid to remove piston smear off the cylinder walls

 

[robert graham]

Re: Cyl/Piston Wear issues-40RL71G

PaulO, If your piston/cylinder clearances are out of tolerance and you can't spend the money for new oversize pistons, then maybe you can have your piston skirts knurled at a machine shop to help take up some slack and retain oil in that area. At least it used to work on our motorcycle engines.....Just an idea! Good Luck!

 

[PaulO]

Re: Cyl/Piston Wear issues-40RL71G

In addition to clearances, I told the engine rebuilder the bore was 3.187" but the manual says 3.188". I think I gained .001"...Yippee!.. I think?