Farmall M Funny noise and rebuild price question

My M ever since I've had it makes a knocking noise but it doesn't sound like a typical rod knock. My FIL says it made that noise while he had it too. I put a stick all over the engine as a stethoscope and it seems to be coming from behind the timing cover. The engine also misses quite badley as well. I only use it around my house (1 acre) and is a loader tractor so It never runs a ton. Usually never gets warmed up but when it does at idle there is no oil pressure and at full throttle warmed up I get no more thatn 10-15. The head was replaced/rebuilt less than 25 hours ago. My FIL bought it with a cracked head and had it replaced with a rebuilt gas head. The tractor was originally a distillate head. He said it knocked before the new head was put on.

So my questions are what the heck is the noise coming from? And what is a good round number for the rebuild. The head is in good shape and won't need to be replaced. I would most likely re-use the pistons and rods unless it's not recommended but would put in new sleeves and bearings. I want to put the later timing gear in it as well since I have a live pump that will run my Behlen power steering when I get around to putting in on. And what would be the difference in price if I put in the High Altitude pistons to get a few more HP. Some day I hope to have have a few more acres and do some hobby farming or hay work and this would be my tractor. I will do all the work my self with my Grandfather. So I guess I'm really looking at the average price for parts.

Or does it just make sense to fix the knock and not worry about the oil pressure or fix the knock and put in new bearings to solve the oil pressure problem. I don't really have any blow by. I have not run compression and they may be more telling.

Thanks for letting me ramble.

T.C.

Until you tear it down, youre really not going to know whats wrong with it, BUT...if it were mine, and knowing what all is wrong, Id tear it down a rebuild it. There are countless vendors on the net, google, and your local Napa can get you a kit as well. Napa, and one other place I buy parts from, could get me the sleeves without pistons, but most sites youll find on the net will only have a piston/sleeve set. You need to find a good automotive machine shop, and have your crank checked BEFORE you order you bearings.

The knock could be the cam gear coming loose on the camshaft. We had that happen once, and it was a relatively easy fix, but it did require pulling the entire front end assembly off the tractor to get the front cover off.

The oil pressure is probably bearings. If the journals on the crank aren't too egg-shaped, you can get away with simply sliding new bearings in.

I'd say you have bearing problems. A good tight M engine will hold 60-70 lb oil pressure at WOT all day long. Hot idling should be at least 35-40. As for sleeves, good luck finding sleeves without matching pistons. An auto machine shop could probably do this for you but probably as much $$$$$ as new matched set of pistons and sleeves.

The noise might be a broken cam drive sprocket. They will crack and still work but make noise and the valve timing will be getting worse and worse. The Keyway in that gear is also suspect. Replace it with a gear from a SMTA, 400, or 450. This gear is much stronger and designed for Live pump use. The oil pressure issue might be as simple as a repair and flattening of the oil pump cover plate. They can warp allowing very low oil pressure. Easy to fix. It needs .001" to .0005" clearance. (Use shims carefully to set clearance) Clearance is determined using thin gaskets.
Sleeve and higher compression piston Kits will be in the 500 to 800$ range. Add the Coolant and hoses etc. and still less than 1000. JimN
JimN

That sounds like an aweful lot. I was hopeing I would get a way with 2-300. Guess I'll start saving. If it is the cam gear I don't think it's worth fixing until I rebuild the engine or would it be better to tear that front bolster off and fix that sooner? I've never had an opportunity to really dig into the insides of an engine so sorry for all the questions. That's why Grandpa will be helping me rebuild the eninge. I need to learn from one of the best. he's in his 80's now want to learn from him before his health problems to allow him to help teach me!

thanks

T.C.

Any opportunity to work with your granddad is one to be cherished. I am fortunate to have worked with both of mine, and would not trade it for anything.
It is a major piece of why I am who I am.
The gear can wear a hole in the front cover and destroy that. If you have an older M (pre mid 1951) I would begin a search for the Front cover gear and parts.
I would also suggest putting a pan gasket and oil pump shim gaskets on the list to see if pump repair can improve the oil pressure. I would not run it as it is on the oil pressure you indicate. Best of luck, JimN

Yea I don't ever let it idle. I always keep it where it has at least 5 psi. As far as the gear goes I just need the gear right? I have an M&W pump that will bolt up to my front cover so I just need the gear right? Anyone know the part number of said gear? If I get that I will probably put it on until I have the money for a rebuild. I have had the pan off, when i got it there was 10 lbs of sludge in the bottom of the pan. I've run it for almost a year now and am going to drop the pan again to clean up an other residual that came out. I'm not exactly sure what you mean by shimming the pump. I understand the concept of why but not the how and where or where to get shims for that matter!

Thanks for all you help again.

T.C.

The pump has two simple gears inside. The end play of these gears is a very tight tolerance against the cover plate. (as discussed above)
The covers warp (they are not cast iron) and leak substantially when they do. Flat sand the cover to take out the warp. use 250 grit on a piece of flat glass, in a circular motion, then as it just gets flat, use 400 grit paper. When putting the cover on, the pump is free to turn. Use a gasket combo (caseIH) that is close to the original gasket.
Shim material can be purchased from NAPA or others.
You will need .0005" and .001" brass shim stock.
Put a small piece of .0005 shim stock (about half a penny in size)between the end of the gear and the cover. As you tighten the cover evenly and carefully, keep moving the shaft a little. If the cover can be tightened pretty tight, you know it has more than .0005" clearance if it still turns. Now use the .001" stock, (take out the .0005) and again tighten slowly and evenly. If it now locks up before the bolts are snug, the clearance is less than .001". Pull the shim out and you can put it together. If it does not get stuck. the gasket is too thick, or too many (they are very thin). If it gets stuck with the .0005" shim it needs to be thicker. I hope this helps. caseih.com has a parts diagram for the gaskets, and look the part number up for a Farmall then select 400, then select engine. JimN

Perfect! Thanks Janicholson. You always have the answers.

T.C.