John Deere M running on 1 cyliner

Jay Chrisman · Jul 6, 2014

I have a JD M that will only run on 1 cyl?
I have rebuilt engine
I have all new electronic ign wires plugs
rebuilt carb from carb shop
checked valves 2 times
changed plugs and checked timing with light
manifold is the only thing that"s not new?
What next? thanks

jCarroll · Jul 6, 2014

tell us:
which cylinder is not firing
what is the compression in each cylinder
why you have electronic ignition

Mark-Ia · Jul 6, 2014

Maybe the dist. cap has a crack. Make sure the one you get is for the model M and not a 520/620. They look the same, but they're not.

Jay Chrisman · Jul 6, 2014

also new for m thanks

Jay Chrisman · Jul 6, 2014

Rear cylinder not firing ,will check compression,I thought electronic would make it run better.

Nick Renchen · Jul 6, 2014

Did you get copper core spark plug wires? It happend to mine one time and it was a loose plug wire. Also make sure the distributor cap is on correctly. One side has an indentation. You might have already done that but thats where i"d start.

Jay Chrisman · Jul 6, 2014

I also have new cap rotor and wires from Stieners for a M

Anonymous-0 · Jul 6, 2014

Try a new spark plug-I had a new one fail to fire. Could hold wire away from seating in distributor cap a little(just enough to get a hotter park) and see if it plug starts firing. Look at picture of distributor in owners manual and make sure it is in the right position. Your valves might not be opening (push rod off or valve sticking and/or not seating properly.
You have to run the traps to see if you can figure out problem.
I installed oil pump 180 deg out and it just backfired-would not run. Had to pull pan and re install oil pump correctly.

Lavoy · Jul 6, 2014

Make sure the cap is correct, unfortunately many times the vertical dist cap used from the Waterloo built tractors is mistakenly substituted for the Dubuque built cap. Putting on the wrong cap will make it miss on one cylinder.
Lavoy

Ray · Jul 6, 2014

Will it fire if you hold the non firing plug wire away from the plug an 1/8 inch or so while running?

James Howell · Jul 6, 2014

"Rusty" one of our 51MTs suddenly started running one one cylinder.

Had a broken valve spring.

Replaced the valve spring and it ran fine, that is until another valve spring broke.

Decided to replace the remaining three valve springs.

Tractor now runs just fine.

Jay Chrisman · Jul 6, 2014

Checked comp and is about 100 .pulled wire away from cap and or plug with no change

Plant Doc · Jul 6, 2014

Jay: You said you overhauled this M? Has it ever fired on both cylinders after the overhaul? If not I would be looking at the Distributor timing. I suggest you bring up #1 cylinder on compression and look at where the distributor rotor is pointing. Then do the same with #2 cylinder and check the position of the rotor. My guess is, if this M has never fired on both cylinders after the overhaul that either the oil pump is off a tooth or two or the distributor needs to be turned about 45 degrees in the direction the rotor turns. If I misunderstood and this M has fired both cylinders after the overhaul, then disregard all of the above.

Jay Chrisman · Jul 6, 2014

No never fired on 2

M-MAN · Jul 6, 2014

Manifold burnt through would cause missing and backfiring but it won't stop a cylinder from firing at all. Compression, fuel, spark at the right time and she will fire. Sounds to me like your timing is off or they sold you a Waterloo dist cap which still makes the timing off on one cylinder. Please explain the timing procedure you used and if possible post a pic of the dist taken directly beside it. I can tell from the pic what I need to know.

nlastovi · Jul 6, 2014

(quoted from post at 16:10:11 07/06/14) No never fired on 2

This may have been answered, but I didn't see it in a quick scan. Is there *spark* at #2? Pull the plug, put in on the wire and hold it to ground. It ought to show nice spark (at least as big and bright as cylinder #1 does).

Dave H · Jul 7, 2014

Did we ever get the question of whether or not the bad cylinder has spark from the distributor answered?

Jay Chrisman · Jul 7, 2014

I pulled the dis and the slot in oil pump is off a little like one tooth. Also my son checked the oil and it had some h2o . I think the head gasket was leaking to. have to dig deeper in to this one

Jay Chrisman · Jul 7, 2014

yes we are getting spark to both plugs . just the back cylinder not firing

Gene Davis (Ga.) · Jul 18, 2014

No one has asked if he put the oil pump shaft in with the John Deere tool to get the oil pumpshaft timing correct. If not used it can put the distributor so it will fire on only one cylinder. Unfortunately in a fit of stupidity I sold mine years ago.

John Deere M running on 1 cyliner

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