51 8n

[Ric0126]

Well as an update on Dad's tractor. I had no luck on improving comp. on 2 n 3 using ATF after two week of soaking so I pulled the head. Head gasket looks ok not blown and all of the valves are opening and closing. So now I guess a ring job is in order. My question would be to do a complete in frame rebuild or just the rings? The cylinders have not been sleeved so i'm thinking she's never been broken in to like this.

 

[souNdguy]

rings?

if comp don't improve with oil it usually indicates Valves NOT rings. if it's super low.. exhaust valves may be burnt.. if it don't come up much.. if it comes up alot with oil but is still low.. then rings AND valves.

complete or not will depend on cyl liners.

not too hard to hand lap valves and repalce rings, ream ridges on sleaves and drop in new main and rod shells on the cheap.. if the sleaves are bad you'll want to yank them and do the whole enchalada.

soundguy

 

[Ultradog MN]

All N series engines were sleeved from the factory.
Forgive me for not following your tractor.
Was this a running tractor? Did it lose power? What made you soak the cylinders. What were your compression readings?
What did the oil pressure read?
Just wondering. Thanks

 

[Ric0126]

This tractor was my Dads. He died five years ago. The tractor was running before he got ill. However, it has been sitting outside under a tarp since. #1 n 4 had compression over 75lbs. 2 n 3 had below 25lbs. One suggestion was to soak the cyls with ATF to loosen rings. I did so and the comp on 2 n 3 did not improve. Pulled the head and checked the head gasket it's ok. Valves are all opening and closing so none were stuck. That leds me to the conclusion that the rings need to be replaced?

 

[TheOldHokie]

(quoted from post at 22:49:27 05/20/10) This tractor was my Dads. He died five years ago. The tractor was running before he got ill. However, it has been sitting outside under a tarp since. #1 n 4 had compression over 75lbs. 2 n 3 had below 25lbs. One suggestion was to soak the cyls with ATF to loosen rings. I did so and the comp on 2 n 3 did not improve. Pulled the head and checked the head gasket it's ok. Valves are all opening and closing so none were stuck. That leds me to the conclusion that the rings need to be replaced?

As UD said ALL N motors came from the factory with sleeves installed. Four [b:2f43ec6f36][u:2f43ec6f36]new[/u:2f43ec6f36][/b:2f43ec6f36] pistons, rings, and sleeves can be purchased as a kit for $150 - do the whole enchilada and be done with it for another 50 years.

TOH

 

[Ramon]

The trick with using oil is to add a couple of ounces and retest the compression to get a rough idea of th econdition of the rings. Even though the valves may be moving up/down, they need to seal also. Look close for burned edges or crud build up around them. Both can cause low compression.
As to sleeves, original style was either 'thin' or 'thick' sleeves. However, a PO may have made the misguided repair and not replaced thme in the past attempting to gain a bit more horsepower. I believe that old Ford (auto/truck) flathead V8 pistons were used sometimes with no sleeves.