Farmall M Knock

Gents,
I was out working on the M today and noticed a slight knock, is rapidly turning in to a BAD knock. At low idle, there is a knocking sound on the bottom portion of the engine. I'm guessing a rod bearing. Now the person I got the tractor from advised that he replaced a "bad" rod bearing, before I got the tractor...but he replaced only one bearing. I would imagine that the crank is probably bad, and has worn the replaced bearing on short order.....or, I suppose another bearing could have went bad. I've got, well, you guessed it, more questions...

My question is, assuming that I decide to take out the crankshaft..to have it ground with matching bearings....does the tractor have to come in half, or can I remove it somehow from underneath?

If the crank appeares to be bad, worn bad that is, then can I have it machined? will the machinist tell me what size bearings to get?

I have not looked at the rod bearings yet, but when I do, is there supposed to be any movement? Any thing else special to look at?

Is it true that I can short the plugs and the knock will stop when I short the bad one?

Lastly, I need an opinion....


Ok, the tractor was essentially given to me, I like it and it seems to like me...but it looks like I'm going to be doing:


At least crankshaft machining and rod bearings (probably a complete rebuild)

New front and rear tires (the ones on it hold air, but thats about it)

And Possibly a new radiatior (don't know why, but water drips from the cooling fan shaft?????), so a water pump too

....AND the front crankcase cover on the engine has a broken off oil cap stud, which is currently JB welded in.....so a new front crankcase cover I guess


....AND LASTLY there appears to be a very slight crack in the block, no leaks from it, I'm not even sure its a crack, but I believe it is...


Now, I really like the tractor and it is obvious that I will have more in it than it is worth... The question is how much more and also , is it really worth even trying to do or am I going to have so much in it that it is ridiculous?


Everything else on the tractor seems decent (lift all pump, transmission, sheet metal etc. etc. I'd like your opinion, keep it going or part it out?




....oh, one other thing, If I proceed, and I put a small fortune in this tractor, is there any "one" part out there that is virtually not available and will render the tractor worthless?




...And one more..........Should I just continue using the tractor with the knock, until it finally dies? Or will this rod bearing problem make it eat itself alive?

if it had a rod knock and a bearing replaced with nothing else done, i'd guess a lot of the bearing material went thru the motor causing more damage. if its got a rod knock now, sooner or later it will come apart, quite possibly toasting the motor.
your tractor has some issues, nothing that a little time and money wont fix. if you do the work yourself, figure throwing maybe 1000-1250 at the motor, including overhaul set, sleeves pistons ect, machine work, head work. gonna need to split it. while in there, i'd put a clutch in too. you will prolly throw maybe 1500 at it, if you need new tires, figure another 1200. you should have a good working tractor at the end of it all. other option is to sell yours as is, prolly get 500 for it, and buy another one in better shape, maybe 1500-2000 tractor.

To remove the crankshaft you would need to split the tractor. Your local auto machine shop can determine if the crankshaft can be saved by grinding it undersize. It may have already been ground undersize. The block needs to be dipped and cleaned of all metal particles. You should have it magna-fluxed for cracks and the head too.
If the local shop can ground the crank undersize have them furnish the correct bearings. If the block isn't cracked you should have new cam bearings installed. Some of the men that post on here have parts tractors, so you may be able to get a good block if its needed. Hal.
PS: Take a look at the clutch while the engine is off and see if the clutch disc is down to the rivets or getting close. Good time to have it relined if it is.

I am not real familiar with the m , But unless I stand to be corrected you will need to remove the engine completely from the tractor , Also removing the fly wheel etc in order to get the crankshaft out. It sounds like someone put a band aid on a bullet wound. Putting new bearings onto a crank that is not true will never give any good results. I would not continue to run the tractor as it is possible that you could end up putting a rod through the side of the block and then you will have an even bigger problem. As far as checking which one is knocking , I have never heard of the short a plug method out ? If it were a main bearing knocking this would not yield any results as everything is still turning, The rod bearings would also still be turning but with less force on the one in question. In my opinion , If you have one that is bad , Chances are the rest of the bearings and crank journals are not in much better shape. If it were mine I would remove the crank and send it to the machine shop and replace all rod and main bearings with new undersize bearings. Also take a good loook at piston and liner wear , As well as valve and seat condition.

I have an early M crankshaft that was done by Baker machine in Des Moines. 10 on the rods and 20 on the mains. Will sell for 120 bucks. central Iowa.

Just to add my vote to the tally . . .

That knock isn't going to go away on it's own, especially if the rod bearing diagnosis is correct.

Best case is you open it up soon, and get the crank turned down and new rod AND main bearings in it. (I agree with the idea of having the shop that turned it get the bearings for you -- saves ANY confusion.) Worst case it that it will blow and take out the side of your crankcase with it. In between, continuing to run it could chew up the journal on the crank so badly that there may not be enough metal left to turn and polish it, especially if it's been turned down before.

As for the rest of the list, pulling a plug wire to isolate a problem won't help in isolating the bearing. That's more for isolating spark and valve problems.

As for critical stuff, having your head and crankcase hot-tanked and magnafluxed will show up any cracks and their severity. Sounds like it would be worth the cost and effort in your case.

Radiator leaks can often be soldered, though not always. If your water pump is leaking at the shaft and it is put together anything like the pumps on Super As and Super Cs, you'll likely be ahead just replacing it. (Tools, press, language that your preacher might object to . . .) They're reparable, but it can be a bear to do it and do it right.

$$? Leaving those honkin' 38" rears out of the formula, you might figure $1000-$1200 on the motor. And to clarify something I read below(because I had to read it three times) the clutch, throwout bearing and pilot bushing will bear looking at while you've got it apart, and might be another $250-$300, not a whole $1500. (Have the machine shop that turns your crank deal with the pilot bushing while it's there.)

HTH

Welcome to the world of "vintage" tractors. Taking them apart and putting them back together is half the fun of owning them! You are going to have to take the engine completely out of the tractor to remove the crankshaft, because the flywheel has to come off and the timing gear cover has to come off. You really need a shop manual before you start. They are not difficult tractors to work on, but you need to know the details, specs, etc., as with any engine. You will need a good jack and a jackstand or blocking to support the rear half of the tractor, and two jackstands or blocking to support the front support casting/front axle. You will also need some type of cherry picker (engine crane) or overhead lift to support the front axle as you roll it away from the engine, then to support the engine as you split it from the clutch housing. An I&T manual will give you good instructions, as long as you are familiar with tractors and engines. If you are a novice, an IH tech manual or re-print would probably be best, as they go into more detail. Have fun!

scotty, sometimes what i think dont come out the same when i type!!!, what i was getting at if he goes thru the motor and clutch with parts and machining, and asembles it himself, he will have 1500 in the motor and clutch. i figure 600 for engine kit, 200 or so for clutch parts, 500 for machinework, cylinder head rebuild, hot tank, cut flywheel, ect, 200 for incidentals.

I am in the process of restoring a 1939 M which had been sitting in a pasture for 25 odd years. I reworked the head, replaced rods,pistons, rings, rod bearings, dressed crankshaft, replaced camshaft, had mag rebuilt, put new clutch, pressure plate, and bearings, new oil pressrue and temp gauge, and rebuilt carb. All the labor to reassemble was donated. Also, had some sand blasting done on major parts. Right now the total bill has reached about $3300.00. Probably a lot more than it would bring to sell, but a very small price to pay for what I am leaving to a wonderful grandson. Also, see OT I just posted. Harley

LOL! I hear ya! I was dangerous enough when all I had was a typewriter. Gimme these delete and cut and paste features and I can get in trouble real quick and wind up sayin' just the opposite of what I meant.