View Full Version : D2 4U Pony overhaul

Cat Yellow1
10-19-2019, 05:27 AM
Good morning, I am planning to pull the pony out of my D2 (4U1826) and replace the rings and bearings because it is burning a lot of oil. There is heavy blue smoke and the oil level will go from full to halfway to low on a 10-15 minute run. My plan is to take the block and crank to the machine shop to see what size bearings and rings I need, which depends on how much the cylinder needs to be bored and the crank turned. Once I know that, I plan to order the parts from Florin Tractor. In my parts book, there are two pistons 1) standard - 2F3665 and 2) semi-finished - 2F3664. If I'm reading this correctly, the standard piston uses the standard rings and the oversize rings use the semi-finished piston. My question is would I need to get the semi finished pistons if I use oversize rings? I'm hoping to use the current pistons if possible.

10-19-2019, 07:20 AM
Unless you can get by with just a hone job to get the new rings seated, you will need new pistons finished to match the new bore size and rings to suit.

10-19-2019, 07:45 AM
it has been many years ago but i once rebuilt a four cylinder gasoline engine that had worn cylinders. the pistons were fine but the cyl walls and rings were worn and compression was low and oil consumption was high. i got with a ring manufacturer and they supplied me with a ring that fit both my original piston and the bore,so i overhauled in frame with new rings and bearings reusing the old pistons and just honed the cylinders. i still have that engine after 20 years or more of daily service and it is just now needs an overhaul again. there are alternatives.

Cat Yellow1
10-19-2019, 05:47 PM
Thanks all. The way it is burning and spewing oil out of the exhaust, I'm probably not going to be lucky enough to get by with just honing the cylinders. Not knowing it's history and how many times it may have been bored, I'll have to see what I have when I take it to the machine shop.

Cat Yellow1
10-23-2019, 03:32 AM
I'm in the process of pulling the pony out. A little background on this...when I bought it, the previous owner told me that he and a friend rebuilt the pony by taking 3 and making 1 out of it, so I'm guessing that rings may have been used from one of the other engines that probably don't match up very well. I plan to take the block to the machine shop and have the cylinders re-bored if necessary, then get new semi finished pistons and rings. The flywheel has slight movement towards the rear, about 1/8" or so, but this is an estimate and I didn't measure the movement. I'll check to make sure the dowel is fitting in the bearing like is should, but I'll also take the crank to the machine shop and have it checked also.

A couple of questions I do have now though...

1) the flywheel doesn't look like it will clear the hydraulic crossover lines, so my plan is to disconnect the line on the left side of the fender and hope that I can move it enough for the flywheel to clear. Would it be easier to remove the flywheel while the pony is still on the diesel engine or does it not really matter?

2) I think I have all of the mounting nuts and (2) capscrews loose from the pony mount, but I cannot move it with a prybar. I was just trying to see if it was loose. I took 3 off of the right side, 3 off of the left side, and 2 off of the front. Those are all I could see, but I'm going to double check tonight. I'm wondering if the previous owner used adhesive on both sides of the gasket and the pony is glued to the diesel engine. If that is the case, what would be the best way to get this separated? Would using a heat gun around the bottom of the pony block do the trick? I haven't tried lifting it yet, so maybe it will come off a little easier than I'm expecting.

That's all for now.

10-23-2019, 04:55 AM
You should have 1 more bolt on rear and not easy to removed

10-23-2019, 05:39 AM
Gemdozer is correct!
Down under, way in the back is more hardware!
You got all the hard to remove ones under the cylinders, right?
Its been a LONG time since I have pulled one so I maybe (?) off a little in my thought process.

10-23-2019, 08:34 AM
There are 13 nuts/bolts to remove. Obviously don't pry too hard or you'll break the casting. If your pistons can't be used, you can get new ones from JP Pistons in Melb. Oz.
It might be easier to remove the flywheel once the pony is off the machine only because you can get at it easier rather than leaning over the fender but otherwise, no difference. You need a puller with two bolts threaded into the flywheel

10-23-2019, 09:50 AM
The attached photos are of a 2A3483 gasket as used between the pony motor and flywheel housing. There are 8 bolts as shown and 2 locator dowels.

To make re-assembly easier, I was taught to remove the stud that the pencil is pointing to from the flywheel housing, and drop a 1'' bolt through the flange of the pony motor before lowering it onto the flywheel housing. It's much easier to start that bolt by lightly pressing on it's head with a screw driver, while turning with a long handle wrench, than it is to get a nut started on a stud.

10-23-2019, 04:49 PM
Great suggestion Wayne. I have similar templates from my gasket set as well. JM

10-23-2019, 05:26 PM
I'm a bit confused--Cat Yellow1 said he removed the 8 bolts that the holes show on the gasket, but Gemdozer says there is one more to remove in the rear, and Neil says there are 13? are all these others outside of the gasket area??

Cat Yellow1
10-23-2019, 05:27 PM
I've removed all of those in the photos that Wayne shared. The two front were capscrews as well as the middle on the right side. I was able to try from the rear under the cylinders this evening and got a little movement, enough where a little coolant came out. I'll go ahead and try to lift it on Friday, and hopefully it will lift off ok.

I unbolted the hydraulic lines from the fenders on both sides and I think I'm able to move them enough for the flywheel to clear.

Neil - I've only removed 8 nuts and capscrews. Do you know where the other 5 are? Thanks for the info about piston supplier.

10-23-2019, 07:17 PM
I'm a bit confused--Cat Yellow1 said he removed the 8 bolts that the holes show on the gasket, but Gemdozer says there is one more to remove in the rear, and Neil says there are 13? are all these others outside of the gasket area??

No, there are no other hold down bolts outside of the gasket area. Sometimes mechanics use gasket cement that make it difficult to break the bond, and the locator studs can also be tight. That you've broken the suction, and see a show of coolant is a good sign...it's ready to lift off.

10-23-2019, 07:46 PM
Apologies, I was wrong - it's eight as bcwayne wrote. I might have been confusing it with the top cover or something.

Cat Yellow1
10-24-2019, 05:24 PM
I tried to lift the pony off this evening but no luck. I have a 1/2" nylon rope around both cylinders, connected to a come-a-long, the other end of which is on my loader bucket. Due to the diesel exhaust pipe, I was only able to get in at an angle, and had the come-a-long on the corner of the bucket. When I tried picking the pony up with the come-a-long, the corner of the bucket came down (and opposite rear wheel started to lift) and the pony wouldn't lift, however, it must have lifted some because more coolant came out of the bottom.

I'm going to try again tomorrow and I'm going to remove the exhaust so I can get a better position and get the come-a-long in the center of the bucket. To reiterate, I've got the 2 nuts and 1 bolt removed from the right side, the 3 nuts on the left side, including the hard to reach one that bcwayne had the pencil on in the photograph, and the 2 bolts on the front, next to the diesel engine removed. I'm assuming at this point that it's just heavy and should lift off after I reposition the lift point to the center of the bucket. Just wanted to make sure I wasn't missing something. I suppose it's possible there may be adhesive on parts of the gasket that's holding it also. If anyone has any ideas, please let me know.

10-24-2019, 06:32 PM
Try a small pry bar between the diesel head and the pony motor and gently see if you can wiggle it. The modern sealers really glue pieces together but if you're seeing antifreeze you should be close. A 5j I took apart had silicone sealer on the gasket between the diesel and pony water jacket and it wouldn't lift up until I broke that seal by prying back and forth GENTLY

10-24-2019, 07:12 PM
If you are lifting straight up, the intake manifold of the pony gets caught under the lever that actuates the decompression mechanism for the diesel engine, where that cam action lever enters the aluminum valve surround.
As you begin to lift, tilt the pony to the rear to clear. If my description is not understandable, I can post a picture Friday.

10-24-2019, 07:15 PM
Another technique is to get a putty knife and slide it in everywhere you can reach to release the gasket surfaces. I also tap it in with the hammer. You don't have to worry about damaging the sealing surfaces and you know where the dowels are. The only part that hangs down is the idler gear on the front side in that gasket opening. The more you can get, the easier it will release

Cat Yellow1
10-24-2019, 07:44 PM
Thanks Gary, bcwayne, & Neil. I think repositioning my lift point and trying what you guys suggest will do the trick. bcwayne - no need to post pictures, I understand what you're saying. It's pretty tight between there and the hydraulic lines, but I'll tilt it towards the rear as it begins to lift.

Cat Yellow1
10-27-2019, 07:13 PM
Tore into the pony today and found out what the noise I heard was and why it was smoking and blowing oil out of the exhaust. Seems one of the wrist pin retainers in cylinder 2 broke and the wrist pin scoured the cylinder wall. The pieces from the retainer ended up between the wrist pin and the retainer on the other side. Looks like the pieces damaged the piston also. I'm hoping to be able to sleeve the damaged cylinder. Does this look like it's possible?


10-27-2019, 09:41 PM
I have sleeved a pony cylinder on the mill, worked great & still going. I only sleeved most of the way because the wall is so thin inside the case. Use the thinnest sleeve you can find. Or a .060 oversize piston?

Cat Yellow1
10-28-2019, 03:19 AM
Stephen - I stopped by the machine shop last week before I knew how bad the cylinder was, and was talking to the machinist about the possibilities of size it will need to be bored to, not knowing if it had been bored in the past, and he told me then that sleeving and putting back to original size would be an option. I noticed the wall wasn't very thick also. Really glad I decided to tear it down before it blew. I'm planning on dropping it off at the machine shop on Friday on the way Carthage.