8n rebuild or rings

[nathan]

i have an early 8n with front mount dist, upgraded to 12volt. I have had it for 3yrs used to mow 6 acres and blade driveway. It has lost power and trying to determine if it needs a complete rebuild or rings. or to buy another one and keep it for parts.

compression test
front of tractor to back
first kick 60 on all 4
max it would get to 70, 75, 85, 80
with oil added 60 , 90, 95, 90

thay all got better with oil except the first one dropped. they tractor was slightly warm when test was done since i moved it to the heated garage from the barn. Also it has fouled plugs some in the past and uses a qt every 2 hrs.

thanks for the relpies in advance

 

[Bruce (VA)]

It needs at least a valve job & rings, maybe sleeves. What's the oil pressure?

Depending on your skill level, you can do most all of it yourself; parts are around $500. Or you can pull the engine & take it to a shop; that's about another $6-700. If you do that, and continue the limited use that it's getting now bladeing & mowing, it will out live you!

I'll give you a personal example.

I bought my first N 11 years ago for $2500. Since then, I've done a complete rebuild on the engine & hydraulics. I'll finally get it painted this fall. It's used to cut grass on 3 acres & occasional garden work if the other N's are busy. I've probably got $4500 in the tractor. This tractor will be running just as well 10 years from now as it is today.
50 Tips

 

[nathan]

oil pressure runs around 20 to 25 may drop some after a few hours to 16, 18

 

[Bruce (VA)]

What is the oil pressure when the engine is at operating temp & at idle?

 

[souNdguy]

I agree with bruce. this is a valve job, and ring and sleave candidate. might as well chip for front and aft crank seal and main and rod bearings even if you just go back in with what it had.

the numbers deffinately show valve involvement.. and not enough improvement to point to a ring-only job.

soundguy

 

[nathan]

operating temp full speed is 20 to 22 and idle it is 1round 10 to 15

 

[lha]

It just depends on several things,money,which is a variable that you can't do much about usually.You can save up money,and wait,or you can put rings,main and rod bearings,and hope that they'll be better than you had before.I've done that before,and the motor lasted 10 yrs before it was in the same shape as before.I would check very carefully the oil pump,and replace the gears if necessary.Of course front and rear main seals gotta be replaced.Valves can be freed up and lapped if not burned,etc.---lha

 

[TheOldHokie]

(quoted from post at 21:44:01 02/11/11) operating temp full speed is 20 to 22 and idle it is 1round 10 to 15

If you are tight for money $150 will put all new rings, pistons, and sleeves in it which will go a long way to improving compression. Oil pressure is adequate if not stellar - you can throw some bearings at it if you want but that isn't going to fix a worn crank and with those numbers I'd put the closest undersize rod bearings in while the pistons are out and put the mains on hold for a later day when the crank can be mic'd and properly reground. You probably have valve issues as well. At a minimum remove the valves and have them reground or replaced if burned. You may find that the cost of new valves/springs/and retainers @$110 is very nearly the same cost. If the seats are not burned or badly pitted clean them and lap the new/reground valves in - not something I normally endorse but better than nothing if you are going low ball. If you have a seat that needs replaced or reground you are going to need a pro to do it for you. Slap it all back together and you have maybe $350 or less invested and you'll likely get a few more years out of it before the oil pressure gets so bad you have to do something more comprehensive. When I was young and "poor" I did a number of these sorts of jobs and while they bought me some time for a minimum $$$$ outlay I've since concluded they are not cost effective in the long run. Better to do a complete job the first go round if you have the time and the $$$$.

TOH

PS> By all means rebuild the oil pump while you are in there - that may get you a bump in oil pressure

 

[G6 at Snook, TX]

I have a sidemounted 6v 52 that has some life left in it, but it smokes a little, though I was able to mitigate that with some lucas oil, sea foam, and atf in the cylinders. I think the rings were dirty and partially stuck. My point is that cheaply I got that done, but the compression test still tells me that I will have to overhaul the motor in the next 5- ten years, depending on usage. When tat time comes, I will overhaul it stem to stern and let my local machine shop do that for me. While I have it open a new clutch kit and transmission seal will go in as well.

Moral of the story, if you have the cash, do the full overhaul, once, and don't worry about it again for the balance of your life if not your entire life.