New-to-me JD-A and JD-B Repair Tips

[Mnethercutt]

Howdy folks, got several different questions regarding my new-to-me JD-A and B that I'm gonna post in one thread so feel free to address one or all of these questions if you have thoughts.

Background: Purchased 3 tractors as a lot deal, a 1948 Farmall H, 49 B, and 50 A. None of them ran, and from what the previous owner (who had inherited them after the original owner passed) told me, the B had ran "several years" ago and he had no idea when the last time the A ran. After getting them trailered and back home I've spent the last few weeks working to at least get them running to identify if they're worth trying to repair now and get puttering around the yard, or hold on to them till I'm in a position to fully tear them down and do an end-to-end restore. I've got a few issues I'm looking for advice on before moving forward.

On the A:

1. The motor is locked solid. I've filled the cylinders with a mix of ATF and Marvel Mystery Oil and poured diesel in the crankcase. After a month of sitting I've got it where the crank and bearings have broke loose but the cylinders are still stuck. I pulled the crankcase access cover and can see movement in the crankshaft when I try and turn the flywheel by hand. The good news is that I borescoped both cylinders and while they have a fair bit of 'gunk' in them, the cylinder walls look decent and have minimal rust. What I'd like to try is hooking up my air compressor to one of the cylinders that has both valves closed and pumping air slowly into the cylinder to break the piston loose. My thought is that it would act almost like a power stroke and help get things moving. Is this a terrible idea? What other options are there that y'all have tried? To be clear I'm not about to dump 100PSI into the cylinder. I'm thinking slowly going up to something like 40PSI and seeing if that would work. The tractor does not have front tires on it so pulling it to break it loose is not a viable option.

On the B:

1. Like the A, the motor was locked up but came loose almost immediately with a little pressure on the belt pulley. Unfortunately the valves did not cooperate and after several attempts to free them I was forced to pull the head and remove them. I've got them cleaned up and am getting ready to reinstall both the head and the valves after a good cleaning and lapping, but am looking for general tips and tricks for success. This is my first time working on a horizontal shaft engine so the process is different than what I'm used to.
2. As you would expect, the studs and nuts for the manifold were...uncooperative. All 4 nuts immediately snapped off. I got the manifold off but now I need to replace the studs. I tried to get 2 of them out by soaking them down with PB blaster for a few weeks then welding a nut onto the stud....and they broke off at the base of the head. So I'm sure I'll have to drill those 2 out. The other 2 have also been soaked but I held off on the nut welding trick since it went so poorly. Any advice on getting those out or am I looking at drilling and possibly tapping?
3. Can I replace the manifold studs with grade 8 bolts? I'm sure Deere had a reason for using studs, but it seems like a much simpler design to just use a strong bolt (and a copious amount of anti-seize on the threads) to make things easier. Anybody done this?

Any other tips or tricks y'all have for these would be appreciated. I've always wanted a Johnny Popper and am very much looking forward to preserving these two pieces of history. Just hoping to do it with as few mistakes as possible.

 

[Dan in Ohio]

Get the model B service manual that covers everything and most will pertain to the A as they are very similar, SM2004.

 

[Bob Collins]

Do NOT use compressed air to try to free up the "A"! If and when something breaks, you have what is properly described as an explosion. Alternately, break the center out of a spark plug and weld on a grease fitting, then you can truly slowly apply pressure with a grease gun, since the grease will not compress much if something breaks all you will get is a spurt of grease. After it frees up, a few slow turns of the flywheel by hand will clear most of the grease out and some will squeeze past the rings helping the cause.

 

[Rich'sToys]

Do NOT use compressed air to try to free up the "A"! If and when something breaks, you have what is properly described as an explosion. Alternately, break the center out of a spark plug and weld on a grease fitting, then you can truly slowly apply pressure with a grease gun, since the grease will not compress much if something breaks all you will get is a spurt of grease. After it frees up, a few slow turns of the flywheel by hand will clear most of the grease out and some will squeeze past the rings helping the cause.

I had also read one time that this was a suggested method to use. Never had reason to try it myself.

 

[Steven Allen]

Since you had to pull the head on the B for stuck valves, it's likely you've got them on the B, too. Go ahead and pull the head and get the gunk out of the cylinders. It doesn't sound like short cuts are going to work for you.

 

[Mnethercutt]

Get the model B service manual that covers everything and most will pertain to the A as they are very similar, SM2004.

View attachment 6357

Already got it. It was the first thing I bought after I got the tractors.

 

[620 John]

I got grade 8 bolts in my manifold. Hasn't leaked yet. I did use Permatex ultra copper silicone on the threads though. Get a good set of drill bits, a cape chisel, and a tap (think those are 7/16"??). WHATEVER YOU DO DON'T DRILL TOO FAR INTO THE PUSHROD SLEEVES. Use a center punch and try to get it centered in the stud as good as you can. Once you drill through it with a small drill bit keep going bigger until you are about to the threads. Use the cape chisel to start chipping out the stud. Once you get a few threads in the head cleared, use the tap to cut little by little further into the stud. Sometimes the tap will actually grab into what's left of the stud and it will unscrew from the head. If it doesn't just keep chipping away with the chisel and tap. Sounds easy on paper but takes some skill and patience to get it done.

 

[Watthour]

I had a '39 A that had the optional "stuck ring package" which was added probably sometime in the 1990s. One consideration is that it is likely not just one set of rings that are stuck, and you're fighting both pistons. I had fashioned a spanner to engage the two flywheel holes with about a 4-foot section of steel channel as the lever. I worked on that for a couple of days, trying to swing the flywheel in both directions, constantly adding oil to the bores, applying force to the lever and adding a few sharp blows with a mallet as additional encouragement. It was either going to break ring lands, or break the rings free. I never even pulled the valve cover on that one, and it left here running.

One crazy/desperate thing I tried was to remove the plugs, open the compression reliefs, and heat the chambers with a medium brazing tip stuck through the spark plug holes. It had to be an oxy/acetylene torch so that the flame had its own oxidizer after being stuck well into the bore. I'm not sure it helped, but it didn't hurt.

 

[Watthour]

I also had a pair of '36 Bs, one of which was stuck. That turned out to be an exhaust valve, and it ended up breaking a rocker arm as a result. I got it freed up in place, and repaired the arm rather than wait for a replacement.

If you ever do that, understand that the rocker arms are cast. I found out the hard way that they are not cast iron, but cast steel. After cleaning off the mess I created with the TIG after the first attempt, then changing to the correct filler and shielding gas, it also went on to the "done" pile.

Ironically, after doing that and sorting through another barn full of parts, among the cranks, blocks, pistons, bearings, rings, clutches, radiators, and everything else, I found more rockers just ready to be used. I left the repaired one on it.

 

[J.Wondergem]

Since you had to pull the head on the B for stuck valves, it's likely you've got them on the B, too. Go ahead and pull the head and get the gunk out of the cylinders. It doesn't sound like short cuts are going to work for you.

I think that you meant A too. correct?

 

[Fixingfarmer]

tried one piston at a time? not so much that only one gets stuck as it takes less to break 1 loose at a time. honestly after that its time to thump on it with the big hammer and a wood block on the piston. Tire changing heavy slide hammer will thump pretty good. The grease idea sounds like a mess but I've never tried it so won't knock it. if you wanted you could reduce down that spark plug hole size with some bushings from the hardware store. One cylinder will probably take more than the other by a significant amount but I suppose you could look at the connecting rods in the back see which one is closer to the head and take the valves loose of that so they are both shut. If its super close to the head you might not put much grease in at all!

 

[Steven Allen]

I think that you meant A too. correct?

Yeah, sorry.

 

[Mnethercutt]

Thanks for all the info y'all. Good to have.

Working to order parts for the B. Can anyone confirm that this is the correct head gasket set? I've got the All Fuel engine but not sure if its 190 engine or not. Agkits has the gasket set way cheaper than anyone else (especially w/ shipping).

 

[Fixingfarmer]

It says it’s the right one for your 49.