JD Model H blown head gasket?

Brian King

New User
I just rebuilt a 1941 John Deere Model H. Sometimes it can be a little fickle to start so when it is I tow it behind my truck and bump start it. I did it before and it started fine. Yesterday, however, when I popped the clutch the left wheel was attempting to (and partially succeeding) in turning backward while the right one was turning forward as it is supposed to do. This is all while towing it! The end result was that water ended up gushing out of the exhaust stack. Cylinders were full of water, carb full of water, etc. I can only assume I blew a head gasket.
Question: what in holy heck could have caused the left wheel to turn backward, and was that the cause of my supposed blown head gasket (ie: did I hydraulic the motor)? Hoping I didn't do more damage than just a gasket....
 
When the drive train is locked up for whatever reason as long as it is "forward" of the differential they will do exactly as you describe. If you're pulling it forward, which ever wheel has the most traction keeps going forward but the one with less traction rotates backward. If you put the tractor in gear & jack it up so that BOTH rear wheels are off of the ground and roll either wheel forward the other will go backward. This is the differential's action working as it should.
 
You should always pull your 2-cyl. in high gear when attempting to start it. both wheels will roll forward, not fight each other.
 
I agree and it was in high. In response to the other post, I get how open differentials work. Still, I just can't wrap my head around why it would try to spin backward when being towed on a straight line over asphalt. Just doesn't make sense.
 
That makes sense to me, the engine was water locked before you released the clutch. I would be surprised if you did not bend a rod or something more serious.
 
Buck eye mentioned 'traction'.
Teddy mentioned 'traction'.
Think - traction.

That will explain what was going on with the one wheel spinning back, due to the differential...
I hope nothing got bent or broken.
 
That certainly is a possibility. I'll take it apart and see what I find. But the part that gets me is still why the differential was acting that way when I was towing on a straight piece of asphalt. What's to stop the same thing from happening again once I repair the motor?
 
In the H you have one bull gear with a cast differential assembly in the center of it.

The differential assembly supports a 45° bevel gear on each side serving as the axle drive gears, one for each axle. The splined inner end of the axle slides right into these axle drive gears.

Between these two axle drive gears are two 45° bevel pinions which horizontally span the gap between the vertical 45° faces of the axle drive gears.

Now you have two vertically faced gears standing face to face (not touching) with two 45° HORIZONTALLY facing bevel pinions spanning the gap between the two axle gears.

The bevel pinions ride one single shaft that is supported by the center casting of the differential assembly. Under normal the bevel pinion shaft tumbles end over end as the bull gear rotates. If that differential assembly and the bevel pinion shaft is NOT moving (for whatever reason) then the wheels cannot simultaneously roll in the same direction!

If the differential doesn't move then the rear tires will either skid or roll, one forward and the other back.

The rear wheels and drive train will continue to work like this until either the bind (whatever is locking the system) disappears or something breaks! Sounds like your head gasket is what "broke".

I've seen the key between the high speed (third gear) and the bull gear's drive pinion shear. Most everything has to come out of the transmission case to fix that so you may be lucky if the head gasket is all that broke!

Hope that helps.
 
Anytime you pull a tractor in too low a gear or engine locked, one wheel will turn backward. Remember when you were a young hotrodder? When you got on it the right wheel would spin. If you were in reverse the left one would spin. Now if the tractor is heavy enough you probably have a bent rod.
 
My H hasnt been used for 2 years.I pulled the plugs and found water in one cylinder.I question towing a tractor to get it started.Forget a wheel turning backward and find out how the water got in.First step in starting any tractor is making sure the engine isnt stuck.
 

If you don't like the tires turning the opposite direction when towing it, you can weld the spiders together. That will fix that, but you won't be able to turn, or use the wheel brakes.
 

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