John Deere 1939 B question,, need help thx

[jongurley]

Hey guys I have just bought a John deere 1939 B and it has ran like a sewing machine the last two days since I bough it, the guy I bought it from had new valves and etc put in the head. the engine has super compression, ran and started perfect. well me and my dad ran it yesterday around the yard ran great, put it up and went out today to start it again and it seems like it doesn't have any compression hardly, I slid valve cover back a bit and all valves are moving fine(no stuck valve) , could it be that the john deere has jumped time, Im not sure on how these engines are timed as far as camshaft goes, could something have spun and caused the cam to be out of time , the tractor hit every once and awhile and puffed out of the breather under steering wheel...

 

[Greenday]

Jumping time is pretty unlikely. Did you shut the fuel off when you put it away? If not you could have a crankcase full of gas.

 

[jongurley]

Hey greenday, yes the fuel was shut off..

 

[jongurley]

And not doubting your suggestion greenday, but how would that affect compression.

 

[Rusty wheel]

Checking compression is quick and easy. Remove the plug on the flywheel side. Reconnect to plug wire. Bring left hand piston up on compression stroke just until plug fires. See if left hand piston is at tdc. It should be. Also see if left hand impulse mark on flywheel is lined up with emboss on casting. It should be at 3 oclock position. If these conditions are met the tractor is in time. Maybe you lost the head gasket?

 

[jongurley]

Hey Rusty, thanks for the reply, the day we put it up the compression felt cranking it with the flywheel was alot, it was very high, took two hands to turn it through. now when we came back out I can spin the flywheel with one hand. so I know the compression is low. my question is why. I would think I could see a blown head gasket, now the guy we bought it from did redo the valves and put the head back on, I guess the head gasket is possible, I wonder if I could her the loss of air or hissing ,, if head gasket was blown.

 

[Greenday]

johngurley.If you wash down a cylinder wall with to much gas sometimes it will break the seal between the cylinder wall and piston rings that the oil makes and cause you to loose compression.To cure this you simply pump a few squirts of oil into the cylinder through the spark plug hole.

 

[B from Texas]

Are you sure the valves were moving or just the rocker arms. Could be the lock nut(s) have come loose. Pull the valve cover and check the valve clearance.