Unsticking 720 Diesel.

Anonymous-0 · May 30, 2014

ok,,, im wanting to put some penetrating oil in this 720 JD diesel.
I saw the pony engine. I dont put it in there,
so where do i put it for the diesel to get it into the rings assuming that nothing else is stuck.

jr1983 · May 30, 2014

You're gonna have to pull the injectors. I know on older jd they had compression releases on them you might be able to push some up there somhow but dont think a 720 has them. I use automatic transmission fluid.have unstuck a few farmall and one case like this. They ran well after. If it was mine I would pull the injectors fill the cylinders with atf completely and let it sit for a week or two. Does the pony motor run? Not sure on one of these but on an electric start I have always had better luck using the starter to break one free than pulling it ect.once it breaks free I turn the engine over till the fluid stops coming out before reinstalling the spark plugs, injectors ect. When it starts you might call the fire department and warn them as it will smoke out about 80 acres before all the atf is gone. One other option if your going to use diesel is to drain the oil and fill the crankcase till it overflows. Might want to make sure you drain it well.

tlock0331 · May 31, 2014

hold the compression release lever back and have someone dump in your favorite concoction of penetrating liquid down the exhaust pipe till it runs out of the exhaust manifold.

buickanddeere · May 31, 2014

There are lots of other places for an engine to seize besides rings to the bore.
Are you sure you want to brute force it until something gives?

El Toro · May 31, 2014

You probably should remove the cylinder head. Then see if the engine is free. Hal

Scott 730 · May 31, 2014

(quoted from post at 08:03:24 05/31/14) hold the compression release lever back and have someone dump in your favorite concoction of penetrating liquid down the exhaust pipe till it runs out of the exhaust manifold.

If you are lucky enough to have the crankshaft positioned properly the best you will do is hold 1 valve open. You need to pull the head and see what you have.

jr1983 · May 31, 2014

I know its not what you're getting at but it reminds me you should pull the valve cover and make sure the valves are free you dont want to kiss a piston.Back in the day (early 60's) when an unstyled b was considered garbage the going price was $75 if it ran and $50 if it was stuck my grandfather would buy one for use in the timber and pull it down the road with the family station wagon. He couldnt pull the thing with the clutch disengaged so he would get it up to speed and someone would jam the tractor into gear till it broke free. They never had problems from doing this. Im not saying its a good idea or remotely safe but it has been done. Also to anyone who doubts me on this post I would ask who could possibly make this up?

tlock0331 · May 31, 2014

(quoted from post at 14:19:16 05/31/14)

(quoted from post at 08:03:24 05/31/14) hold the compression release lever back and have someone dump in your favorite concoction of penetrating liquid down the exhaust pipe till it runs out of the exhaust manifold.

Click to expand...

If you are lucky enough to have the crankshaft positioned properly the best you will do is hold 1 valve open. You need to pull the head and see what you have.

call me lucky..ive done this on 2 70s, 2 720's and an 830.

Robert Major · Jun 1, 2014

Hi I would not dispute your story I did the same
thing with a Nuffield tractor about 15 years ago .
it either came free and ran or the guy that owned
it wasn't gonna sell it to me, and part it out.
we got it free and running by jumping the clutch
for about 3 miles. i brought it and re built the
motor. as it had a bad habit of dropping
sleeves,that no body could figure out. Guess the
water pump impeller had fallen off!and it wasn't
circulating water to the back cylinders.
The only thing I can see now is most of these old
girls have sat another 40 to 50 years since last
use and are well rusted and full of condensation
in the bores.
Personally I'd be doing it right the first time
and tearing it down and getting it before
something expensive got wrecked or I put 4 days in
trying and still had to tear it down due to stuck
rings or bad valve seats.
Regards Robert

jr1983 · Jun 2, 2014

I would un stick it first if possible especially because its a two cylinder deere and they seem to stick from sitting and come loose better than most other brands. you dont have to go crazy with stuff but penetrating oil and a bar in the flywheel will probably do it if its stuck solid. If it turns over part way I'd pull the valve cover and probably the head. Stuck solid is probably rust or mechanical. Neither one will make things worse because the damage is already done. If you get a half turn out of it and it stops that makes me nervous. I had a d17 allis that did that. Tried alot of stuff pulled the head the number 3 hole was full of corn. Mice are so much fun lol

Unsticking 720 Diesel.

Anonymous-0

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