MT ring size question

[RonWind10]

Need some advice on my engine rebuild. Got it torn down and the cylinders are in fine shape. Very slight ridge at the top. All I'll need to do is hone them and put in new rings. The bores measure 4.004". With this bore size will standard original size rings be ok? Wouldn't the next oversize set be too big?

Thanks guys. Your expert help is invaluable!

Ron

 

[Kemper]

If you don't bore the cylinders you have to stay with the standard rings and pistons, the cylinders may not look wore but they should be measured near the top and then down to the lower end also, i think they will wear more at the bottom of the cylinders.you will also have to take out that ring groove at the top if you don't bore it.

 

[Anonymous-0]

Excerpt from John Deere Model M service manual:
Original diameter of 4.000 to 4.0001. If wear is not more than .010 of an inch, new rings may be installed. However, if wear is more than .010", it may be necessary to bore cylinder block to .020" oversize.

So with your reading of 4.004", normal size rings will work fine.

For the engine, the model M and MT I believe are the same.

 

[RonWind10]

Thanks for the help! I had a suspicion I was within tolerances for the same rings but this is my first tractor rebuild and I wanted to make sure I understood what to do next.

Many thanks!

Ron

 

[tstex]

Ron,

As mentioned, you need to "mic"'measure the entire distance of the bore [top middle bottom]. If any of the areas are out of tolerance, then you would need to upgrade and check to determine why there is a delta.

I would also have someone look at the p-rod bearings to insure they do not need to be milled some.

AS mentioned, make sure there is no ring-groove at the top, which could damage the piston if you come out/install back in the top.

When breaking in the rings, use a lighter weight oil and follow the tech-service manuals instructions.

good luck,
tstex

 

[RonWind10]

Thanks tstex.

The ridge at the top of the cylinder is so slight I can barely catch it with my fingernail. I"ve been told I can knock this down with the hone. I forgot to mention that I did "mic" the bore and it"s well within limits for round. Next I need to check the crankshaft journals for wear. The bearings are a little scored and there are a couple of areas that have flaked off. No obvious matching damage on the crankshaft though.

Many thanks again!