M Farmall

Bryan Carroll · May 10, 2015

Ok i need help from all you farmall experts. Back in the winter i posted that i could n get the skip out of my M. I finally got time to work on it and this is where i am. Rebuilt the carburetor float was way out of adjustment, changed spark plugs new points &condenser rotor button distributor cap was good. Checked compression & here are the results of that. CYL# 1 140 CLY#3 140 CLY#4 145 & CYL #2 140 With all this said what else could be wrong. Your input greatly appreciated.

DR. EVIL · May 10, 2015

When was the last time you set valve tappet clearance?

David G · May 10, 2015

Valve setting or distributor bushing?

used red MN · May 10, 2015

Realizing terminology varies greatly from local to local to me "skip" in this case needs more definition. (to me that describes a type of walking step) Those compression readings seem acceptable to me. Setting the valves and the distributor bushings are also problems that can cause a "misfire" if that is your problem. Does one cylinder have a constant misfire? I'm looking for a better description of the problem. If the carb was providing a very rich mixture new spark plugs can become fouled with carbon in a matter of minutes and may need to be removed and cleaned. On method to do this is by heating the combustion side of the plug with a propane torch. Another problem could be a leaking intake manifold gasket or broken intake manifold. This can be checked by spaying either or directing an unlit propane torch around the manifold to see if the rpm changes while the tractor is idling. If so you have located a vacuum leak that needs repair.

Pete76NY · May 10, 2015

Bryan, your compressions are all good...as mentioned it sounds like it could be a valve issue, take off the valve cover and adjust all the valves to spec, then see what you have, actually before you do that put a sheet of paper flat over the exhaust and see if it sucks in when you hear the skip...if so its a valve issue!

rustyfarmall · May 10, 2015

(quoted from post at 16:10:07 05/10/15) Valve setting or distributor bushing?

I'll second the motion on distributor bushings.

Bryan Carroll · May 10, 2015

It has been quite a few years since valves were adjusted & distributor bushing changed Also tractor will run good cold then when it warms up to operating temperature the skipping starts. Distributor shaft don t seem to have any play to lead me to believe the bushings are bad

Jason the Red · May 10, 2015

Valve clearance could be an issue. Also check the float in the carb for hanging up on the bowl or carb casting. Another thing to look at is the governor for a broken or worn spring. You say it is skipping, but that doesn't explain much.

rustyfarmall · May 11, 2015

(quoted from post at 18:42:33 05/10/15) It has been quite a few years since valves were adjusted & distributor bushing changed Also tractor will run good cold then when it warms up to operating temperature the skipping starts. Distributor shaft don t seem to have any play to lead me to believe the bushings are bad

Time to adjust the valve clearance gap. The current gap is too small. When the engine gets to operating temperature, what little gap there is goes away completely, and then the valves can no longer fully close. A rough running engine is the result.

Charlie M · May 11, 2015

Check your intake manifold for leaks. If you give the tractor a little choke does the skip go away. If so you have a leak.

Pappy · May 11, 2015

Our "H" would do the same thing. Ran real smooth upon start-up, but would start to miss as soon as it warmed up a bit. Did the propane torch leak test and found the intake gasket leaking underneath on number 3. New gasket, no more problems.

Bryan Carroll · May 11, 2015

Hi guys I think i might have fixed the problem with the skip. Tractor hasn`t been used much in the past year. pulled valve cover cranked tractor over by hand with the help of my son and found sticky valves. Sprayed penetrating oil on them until we got them freed up. readjusted them & put a pint of Marvell mystery oil in the engine oil run for a little. while & change so far so good she ain`t skipped yet Knock on wood

M Farmall

Bryan Carroll

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DR. EVIL

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David G

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used red MN

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Pete76NY

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rustyfarmall

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Bryan Carroll

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Jason the Red

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rustyfarmall

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Charlie M

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Pappy

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