Farmall M Compression

Brice Faulkner · Feb 9, 2011

I was wondering if anyone knows how much compression a Farmall M should have. Mine has 75 PSI per cyl. It always runs out of power when pulling hard.

CNKS · Feb 9, 2011

New compression in an unmodified gasoline (X1) engine is about 120, distillate or kerosene about 95. So, yours is a little low. Keep in mind that a 200 HP tractor also runs out of power if loaded too much.

sflem849 · Feb 9, 2011

30:1 Just kidding...for those of you that followed the gas in a diesel thread.

Anonymous-0 · Feb 9, 2011

The little M of mine with M and W pistons has 140 lbs of compression, and she's a winner in 5500 some of the time anyway. well at least she sounds tough.

Brice Faulkner · Feb 9, 2011

Why would it have such low compression? It has a 8060D Cyl head with step pistons. Any suggestions

CNKS · Feb 9, 2011

It's old. Could be valve seals, but likely that is not the whole problem, probably needs head work, and at a minumum new rings. Complete overhaul won't cost much more.

D Slater · Feb 9, 2011

Did you check with the throttle wide open and have a non restricted air cleaner. may check the valve clearance and cam lift, but if all cylinders are the same pressure thats probably not the problem. One thing that may give you low power and low compression besides a internal engine problem, is the carburetor butterfly not opening completly. Due to a worn governer or throttle linkage system not correct.

Owen Aaland · Feb 9, 2011

Along with the things D Slater listed, cranking speed will also affect compression. That is why it is more important to verify that the compression is close to the same in all cylinders rather that any specific number of PSI.

Farmall M Compression

Brice Faulkner

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CNKS

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sflem849

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Anonymous-0

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Brice Faulkner

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CNKS

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D Slater

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Owen Aaland

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