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John Deere 40 Motor Stuck

M

mr.precision

Member
Over the years, I have always been successful in freeing up stuck tractor motors. Usually patience a a little snake oil mix will get them moving again. It's truly amazing how a stuck motor can be freed up and run pretty well.
Not the case with this Model 40. I've had it soaking for a month with 50/50 acetone and trans fluid. I am not even getting any fluid to leak down to the oil pan. Using a rocking motion with the trans in 4th gear. Starter is out so I can watch the ring gear on the flywheel.
The previous owner claims it ran a year ago. And I am inclined to believe him since he put new tires on it, bought a new seat, new lights, and a bunch of other new parts. Doesn't make sense to spend all that on a stuck tractor.
Next steps? I am thinking of pulling the head and having a look in the bores. Perhaps a wooden block, a little heat.....anybody got a suggestion? If I get the pistons loose, do they come out the top or the bottom?
Open to ideas. I don't like admitting defeat, and with 30 years of playing with old tractors this is the first one I cannot break free.
 
They come out the top if you get that far.
I fool with Hs and have had to put blocks
in a press. They were stuck tight enough
to make the press jump when they broke loose.
 
I had a stuck H block that was WAY worse than any others I have had. I gave up on it. I set it upright on blocks in the back shed and filled it up with diesel. I'm not sure how long it sat there maybe a year or so ? I went back there with a block of wood and a hand sledge and I'll be darned they practically fell right out ! So time does help.
 
I'd say your going to have to open it up for a look. Maybe one is not stuck ? if so you may be able to unhook that rod and pop it up out the top and then just fight the other one. If they are both stuck crank may need to come out so you can heat it and beat it. One time I stuck the wand from a hot water pressure washer in the water jacket and heated up an A block enough to help drive the pistons out. Others light the diesel in cyl. on fire ,but I have not done that.
 
(quoted from post at 09:12:48 02/15/17) Pull the pan too.....maybe something more than just a seized piston. Ben
Click to expand...
What would I look for, Ben?
Wouldn't the snake oil leak to the pan if the pistons were not stuck?
Thanks
 
The Little model M I purchased a few years ago didn't want to budge either. Spent weeks
trying everything everyone suggested... Then my step father said back on the oil lease days
the old timers always used rifle bore cleaner to free up a stuck engine. Already had the head
off & a white oak 4x4 I used to beat with for WEEKS... Dumped in a bottle in each cylinder & the
next morning I had bore cleaner leaking out the bottem, tapped on one piston & it moved....
 
Maybe a broken connecting rod, or a camshaft /lifter issue, anything could lock the
engine internally....even a dropped valve, or something of that nature...unless you
knew the engine was running OK and is only tight from sitting. Ben
 
I've got a 1941 JD B that had run a year ago
too. I had it soaking with the atf and
diesel for 2 months before I could turn it
over. I would give it another month.....
 
You can have the head off in less than an hour and see what you got in there.If
it's stuck that bad your probably going to have to hone the cylinders and install
new rings.
 
I've heard that you can get the water in block very hot, then cool, then hot, then cool several times and this will have a tendancy to loosen the pistons....If you had a block heater would be good to use...would be worth a try....
 
I rebuilt a 40 just like that. Ran a year
before, set around for a bit, seized up.
Checking the radiator revealed it was low,
and pan was full of antifreeze. Head was
cracked, I think it was in the exhaust
runner. Set it up tight, had to have it
bored to max size to clean up the cylinders.
Maybe that isn't your case, but aside from
that 40, I had the same cracked head deal on
an M and a different 40 I rebuilt, only they
weren't stuck from setting yet. Just
something to keep in mind if you notice any
of these things as well.

Ross
 
Thanks Ross.
Cooling system holding anti-freeze just fine. I check the oil pan drain plug periodically to see if any of the mix in the cylinders is leaking down to the pan. Very little getting there. Looks like the next step will be to wait a while or take off the head and have a look.
Would you recommend taking off the rod caps and attempting to rotate the crank before hitting the piston tops with a block of wood? Seems like pounding (or even rocking the tractor in gear) would be hard on the rod bearings. Maybe not.
 
Depending on how the crank is turned, if you
could get the crank all the way out (if the
block is out of the tractor) I would think
that would be much,much better. Unless the
crank throws are at a horizontal alignment,
which is the best chance for a stuck engine
to turn over (but almost never stopped in
that position) I wouldn't pound on the
pistons at all. Even if the crank throws
were horizontal, I'd still be hesitant to
pound on a piston much at all out of fear of
bending a rod.

Ross
 
Took the head off today. Here's a picture of what I found. Used a block of wood to push the pistons down, but no movement. Considering the amount of rust on the back cylinder bore, i suspect it's the same underneath. Tomorrow the oil pan comes off and I will try to drive the pistons out the top. I am still hopeful a wet-hone and a new set of rings will make it run again..... perhaps not once the pistons are out. The front cylinder looks OK, but the rear one is pretty rough.

45882.jpg
 
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