Farmall A - Sudden engine vibration

[adamsih300u]

Hello all,

I have a 1940 Farmall A I bought this summer and have been using for mowing my 3 acres with a 60" Woods mower. It's run well for me, though I discovered after buying a small crack in the block, which I sealed with JB Weld putty and has held well against the coolant.

I just finished an oil change before winter - new filter, dropped the pan to put on a new gasket. There was a slight gap in the oil pump cover gasket which I think has resulted in low oil pressure, but I'm having a hard time finding a replacement.

Anyways, after putting everything back together, I did some fairly heavy mowing and things seemed to be running well. I parked the tractor outside after mowing for a few hours. When I went to start it tonight, it fired right up and started vibrating terribly within a couple of moments. I switched off right away, and pushed into the garage. Tried cranking it with the ignition off, and it cranks and starts vibrating badly after a moment. I've posted a short video here if it helps: https://youtu.be/P0Pu71BHgNE

Thanks for any help and advice! I'm worried this could be a big issue...good thing winter's coming.

 

[J.Wondergem]

Your u tube address said it's private. Anyway, it's sound like it could be a broken crank, but it's just a guess, and hope not.

 

[Janicholson]

There are restrictions on the U tube video.
Without seeing the engine run, there are several things that could cause vibration.
Does the engine vibrate with the clutch pressed down all the way?
does it misfire on one or more cylinders?
Does it have oil pressure?
Does the vibration corispond with ground speed or engine speed?
Jim

 

[adamsih300u]

Whoops, sorry about that. The YouTube video should work now. I had low pressure when running, after the engine warms up. Gauge showed center when the engine first starts.

I will try cranking with the clutch pressed in. The vibration occurs almost instantly, even when cranking with ignition off, and I didn't try increasing throttle with ignition on for fear of wrecking something. There hasn't been any misfiring or other issues.

 

[Janicholson]

The video never gets the engine started. if there is a vibration while cranking, it could be a piece of carbon or junk under a valve face. Jim.

 

[El Toro]

Check that crankshaft to see if a counter weight broke or if the shaft broke. Check those connecting rods too. Hal

 

[adamsih300u]

Thanks for the things to check so far. Here's a minute long video with engine crank and startup, clutch fully depressed throughout, and I throttled up and down (though my throttle lever tends to jump down to minimum throttle on me because it's badly worn).

https://youtu.be/WgxjcXLuhs0

Also wondering - could it be the fan making that racket and vibration?

 

[fixerupper]

If you threw a fan blade you would feel a big vibration but there is a 99 percent chance you would hear some other drastic sounds if that happened. My combine threw a fan blade and I never did find a single mark or scratch anywhere from the blade exiting the engine bay so I won't say it can't leave silently.

 

[gene bender]

You need to drop the pan then remove the main bearing caps one at a time to look for a broke crank. Customer had one like that it would start and run with terrible vibration ended up the crank was broke.

 

[khouse6]

do the simple things first. look at all external parts. have a friend look etc.

 

[adamsih300u]

I took a closer look after work this evening. I started the engine and there was no unusual noise at any RPM. Opened the garage door and ran it around the driveway in all gears with no unusual issues. Pulled it back in the garage and the sound started again...let it run awhile - the sound definitely seems to be coming from the front, as opposed to the middle of the tractor or bottom of the engine. Shut it off, and found I can wiggle the fan a fair bit, seems to be loose on the shaft - probably not normal?

I also noticed a leak of radiator coolant, not sure what's causing that as it's new - but definitely not coming from the overflow tube, seems to be coming more from the left side (facing the tractor) around the bottom stud. I can always pull the radiator to have a look, I imagine I'd need to to work on the fan anyways.

 

[David G]

Be careful with loose fan, can go through a good radiator and make it a bad one.

 

[Janicholson]

remove the fan belt and see if the noise goes away. If so, fan hub!! jim