Todd's 1941 Farmall A Rebuild

[Todd 02]

I picked up a 1941 Farmall A last weekend and intend to make it my first rebuild project. It's clean and mostly straight, but does not run and is lacking a few major components (like a carburetor). I'll try to consolidate and chronicle everything about this project into this thread. Here we go!!!

Home and in the garage

IMG_4095.JPG (146.11 KiB) Viewed 1139 times

Happy little boy

IMG_4096.JPG (150.16 KiB) Viewed 1139 times

All four plugs were clean when I pulled them

IMG_4109.JPG (73.79 KiB) Viewed 1139 times

Valve train is clean and dry

IMG_4110.JPG (144.37 KiB) Viewed 1139 times

[Todd 02]

I started the tear down yesterday and found most everything that is present to be in working condition. Upon removing the oil pan, I discovered a light dusting of rust on the internals of the crank case. No worries as I plan to pull everything and reassemble anyway.

IMG_4137.JPG (122.22 KiB) Viewed 1132 times

IMG_4138.JPG (86.8 KiB) Viewed 1132 times

IMG_4139.JPG (121.99 KiB) Viewed 1132 times

Notice that the piston is nice and shiny. I found all four to be the same. The cylinder sleeves are shiny also.

IMG_4140.JPG (143.87 KiB) Viewed 1132 times

IMG_4141.JPG (142.02 KiB) Viewed 1132 times

As I said above, I've got a very happy little guy who is excited to help. He'll be three in February. Here he is working with his great grandfather's tools. This isn't their first Farmall experience. My grandfather farmed with an H and an M back in the day.

IMG_4142.JPG (124.28 KiB) Viewed 1132 times

[Todd 02]

And finally for my first real worry of the project. I discovered some repaired cracks in the block deck. The water cooling system on this tractor isn't pressurized, though I do have a locked up water pump I could try to rebuild and use. I suspect that I'll just add a little bit more filler into the cracks and move along. I plan to use this tractor out at my farm for little odds and ends.

IMG_4158.JPG (1.75 MiB) Viewed 1131 times

IMG_4159.JPG (1.39 MiB) Viewed 1131 times

I would appreciate y'all's insight moving forward as to whether I should source a replacement block or just reuse this one.

Thanks!

[Eugene]

Bench or engine stand for the engine. Number of things wrong with current condition of bottom end of engine.

Looks as though someone started to overhaul the engine. Not sure why someone would purchase new pistons and sleeves, perhaps replace some crankshaft bearings and then stop.

Timing gear, front of crankshaft. Damaged?

Posted in wrong post. Disregard. Edit: Change Damaged?, to 99.9% sure crankshaft is broken.

[Todd 02]

The previous owner passed while he was doing the rebuild. He bequeathed the tractor to his sister who sold it to me for $450.

[Eugene]

Images #5, 6, & 7. Crankshaft broken?

Edit: Change Damaged?, to 99.9% sure crankshaft is broken.

[Eugene]

Photo #6. Besides the crack in the crankshaft, the piston appears to be cocked in the cylinder. Perhaps it's just the photo, but there appears to be a significant gap between the right side piston skirt and the cylinder wall. Also the connecting rod should be centered on the piston pin.

Thinking the displayed piston is jammed in to the sleeve wall. If this is the case, then that piston and sleeve are probably not salvageable.

[Todd 02]

I've inspected the crankshaft and I don't believe it is broken or significantly damaged.

[Eugene]

I've inspected the crankshaft and I don't believe it is broken or significantly damaged.

The crankshaft arm coming down from piston #1 rod journal to #2 piston rod journal appears to be cracked about 80% through.

[Todd 02]

I really think the photo is deceiving you, Eugene. There is no crack in the crankshaft. I think what you're perceiving to be a crack is where the crankshaft transitions from the round shape of the web to the rectangular shape of the arm.

IMG_4163.JPG (128.49 KiB) Viewed 1037 times

Here is a view looking front to back of the same arm.

IMG_4164.JPG (170.96 KiB) Viewed 1037 times

[Eugene]

OK. Thank you.

Rust appears to be cleaning up nicely.

[WLM Cub]

Don't all the piston's notches go to front of engine? The two middle ones [2&3 ] are to the rear. Just one more commet.. Thanks, [Bill] WLM Cub.......

[CPIII]

I just went though a block replacement on my A. It wasn't half as bad as I thought it would be. I am close to firing it back up now as I just finished going through the mag.
Here is the link viewtopic.php?f=170&t=85461
I would suggest finding another block and not waste any more time on that one because even if the cylinders seal the head will probably leak and the crack will only get worse IMHO.

Edit: Oh and yes all piston marks must face toward the front on the block. Also in my rebuild I accidentally got one of the connecting rod caps on backwards. I couldn't turn the engine over by hand after that because it caused such a bind. I would make sure all the bearing caps and connecting rod caps are correct. Fortunately mine had numbers stamped in the side on the top and bottom of the bearing halves. But I still managed to get one wrong. With everything right you should be able to turn the engine over by hand with a bit of force (not really easy to turn but should move) on the crank arms. If you can't there is something wrong somewhere.

Charlie.

[artc]

It appears the engine was run without water for a fair bit of time. it was common in the day, as antifreeze was not invented and water was used and drained every night. someone forgot to add water in the morning. I would check the head carefully for cracks as well, and finding another block (of which there are still plenty available) would be advisable. if there is a crack in the block down where the o rings seat, then antifreeze will leak into the pan, and all your rebuild work will be for naught.

it also appears that the motor was cleaned, sleeves and (I assume) bearings installed, and the owner fell ill. the rust on the crank I believe is a result of sitting around after the engine work.

I would completely tear it down, replace the block, reuse the new sleeve and piston kit (notches forward by convention but it wouldn't hurt the way it was), assembly lube the moving parts, check the head for cracks and condition of the valve job, and install all new gaskets, making sure to copper coat the head gasket and use vaseline on the sleeves in the contact area of the o rings before installing them. make sure the o ring groove in the block is clean. I can't stress that enough.

your cam didn't look stellar, so if you get a better one with the new block, good. the crank gear probably should be replaced due to rust. make sure the crank journals are polished up nice, or have it done. check rods and mains to be sure the correct bearings have been installed. in other words, don't leave anything to chance. the PO probably knew what he was doing, but he could have been ailing when he did this.

when you install the pistons, install keepers on the sleeves to prevent the sleeves from coming out of the block as you rotate the engine. a plate across the sleeves held down by the head studs will work fine.

check the oil pump carefully. these pumps had a cast bottom plate that warped easily. you will need to flatten it back out, as long as the pump is in good shape.

[artc]

oh, and check the push rods to be sure they are straight by rolling them on the bench.