farmall M rods

LN · Aug 1, 2009

I am putting together an M engine that was a basket case someone else had disassembled and lost many of the bolts I have a question on rod bolts I got new grade 8 bolts but have yet to find the locks like were on them from factory .Do I need the locks ? would loctite be an option? would just torqueing them to spec be acceptable? any input greatly appreciated

mattofvinings · Aug 1, 2009

My opinion is that the "flex-lock" nuts used are a step ahead of simply torquing to spec as they also provide added resistance to vibration.

Best practice, IMHO would be to use a torque-prevailing nut (also called deformed-thread) and set a couple up, cross-drill the free end of the bolt for safety wires once they are fully torqued.

IIRC they are fine-thread and so if possible you will want a "graded" nut as well to make sure the threads simply aren't torn out of the nut under loads.

While what I'm describing is probably somewhat overkill for an engine turning no more than 2200-2400 rpms max, at the same time I don't think any of us can afford the downtime or expense of the lower end of an engine coming apart.

Allan in NE · Aug 1, 2009

Dunno,

I've been turning wrenches since I was 6 years old.

Have never, even remotely, ever heard of a rod bolt coming loose on anything. Just doesn't happen.

Allan

cd1 · Aug 1, 2009

sorry to burst the bubble but I've seen it more than once.

MeanGene1 · Aug 1, 2009

Grade 8 bolts? Not the correct rod bolts? Most rod bolts are carefully sized to fit the rod, hardware store bolts would not be a good idea. Rods are also sized and honed round with the correct bolts tightened to proper torque for those bolts, and may not necessarly be round with a different bolt in them. Best bet to get the correct bolts and have the rods re-sized to insure that they're round- let the machine shop install the bolts, and don't remove them when you get the rods back

Janicholson · Aug 1, 2009

Allan is very correct. using a different bolt (even a rod bolt) is asking for disaster. If the shank of the grade 8 bolt was ground to the exact size of the original, and the nuts were castle nuts, and wired, it would be OK. if there were no possible replacement parts. These rod bolts are easy to find, any salvage yard with tractors will have hands full. I bet CaseIH has them. JimN

Anonymous-0 · Aug 1, 2009

Yeah, just ask Kohler.........

mhmalcolm · Aug 1, 2009

Locks for the connecting rod bolts for a Perkins 318 engine used in Massey 285, 1085, 298, 0r 698 tractors are the correct size. That is what I have always used. I don"t believe they were available from IH over 25 years ago. Any MF or Perkins dealer can get them for you. As far as the rod bolts go, you would be well advised to go with factory replacements. The shoulders act as alignment dowels to make sure the cap is mated to the rod correctly. Don"t shortcut this. And, yes, I too have seen connecting rod bolts fail, usually right after an overhaul where the bolts are re-used and torqued correctly. The threads stretch a little every time the bolt is torqued, and unless you know for sure they haven"t been reused more than twice, or preferably once, I would be replacing with new. Watched a John Deere 2510 put a rod through the block while breaking in a new overhaul on the dyno. The threads were pulled off both bolts. Saw it happen on an MF 1150 also. Very UGLY!

Mike Farmer · Aug 2, 2009

You don't believe it. Take a look at my Wallis if you ever in the south of england. Theres holes in block, bits of internal casting laying inside and an S shaped conrod. Oh! yeah it happens. By the way it was the way I bought it and I did know about it. MTF

farmall M rods

LN

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mattofvinings

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Allan in NE

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cd1

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MeanGene1

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Janicholson

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Anonymous-0

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mhmalcolm

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Mike Farmer

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