Farmall m trouble

Gents,

I was pulling a land lever with my m, I beared down on the hydraulics and hit the end of the hydraulic stroke, the motor snuffed out.

When I tried to restart, it just turned over. Thought it was electrical, replaced all electrical points rotor cap condenser coil. No start

Got the compression tester and run it one time, here's the bad news-

1-75#
2-0#
3-0#
4-25#

I figure it's a broke cam.

Engine has 15 hrs or so on overhaul. I am sick and going to have a beer to ease the pain.

I thought to pull the tappet cover first

Let me know your thoughts
 
See if the rotor rotating when cranking. You may have damaged the cam gear. Bring No1 piston near the radiator to tdc on the compression stroke. Then remove the distributor cap and see where your rotor is pointing. It should be at the No1 plug tower about one o'clock. Hal
 
Assuming it has a after market engine driven Hydraulic pump, or is new enough to allow the use of a Stage 2 SM or newer tractor, it is probably cam related. Either valve cover or tappet cover will tell the tale. Setting the #1 piston at real TDC (whether compression or exhaust) will allow the rotor to point at either #1, or #4. If not it is the cam gear. If the rotor lines up it could be a broken cam, Jim
 
(quoted from post at 22:50:49 04/01/14) Didn't realize belly pump runs off the cam drive on a stock M. Am I missing something?

The belly pump doesn't put out enough pressure to kill the engine like that. If the detent spring breaks and get sucked up in the pump gears the normal result is either a sheared pump gear key or the threads striped out on one of the drive couplers.

Also the compression readings are what you see when the camshaft is not turning. An M with an aftermarket live hydraulic pump was noted for breaking the camshaft gear unless it has been replaced with the later, heavier gear. A system with a non working relief valve can easily break the camshaft gear.
 

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