50 JD B Seized While Running

bmoran4

Member
Had to unfortunately start and maneuver my 1950 John Deere B in the cold snow this evening (9?F with -3? Windchill). She was hard
starting - needed to be jumped. Finally she got running and after about 15 minutes of idling, she stalled and appeared seized.
Too cold to troubleshoot or do anything so now I'm stewing over the keyboard and wondering how expensive this is going to be...
Appreciate any thoughts on how to methodically approach this.
 
MOST likely cause would be that ice in the oilpump caused the oilpump drive coupling to break.
 
(quoted from post at 00:00:45 01/22/19) MOST likely cause would be that ice in the oilpump caused the oilpump drive coupling to break.

How would I be able to diagnose the oil pump drive coupling? If I do find it broken, I presume the repair is likely more than just replacing the coupling?
 
I do not know on the coupling, but if the engine did seize do to lack of lubrication, it will probably take more than the coupling to get it running again.
 
I will second that you broke the oil pump coupling. Common failure on them in cold weather. You can take the cover off the crankcase and reach in and check the coupler. As for damage. Most of the time you will not ruin the crankshaft or rods at idle. Rock it back and forth with the cover off and see what seized. If your lucky and it is just a rod bearing you can often polish the crankshaft in place. Then install new rod bearings and drive on. Replacing the coupling first. LOL If it is the main bearings than your in for more work.

This happening is one design failure of these tractors. The oil pump is the lowest point in the lubrication system. So any water goes right into the pump gears. Then it freezes and locks the pump. This shears the coupler. If your not watching the oil pressure or the gauge is broken then you have it seize.
 
I think 1950 could have had either babbit or inserts. To the op would pull the crankcase cover off and see if the coupler is broken
 
After the crankcase cover is off, follow the shaft up, the pump coupler will be at the top of the shaft.
 
Thanks guys - I'm relatively new to servicing this John Deere B. I tried to find the dip stick to see if I could get an oil level and look for glitter, but couldn't locate it.

As for removing opening the crank case and inspecting the bearings and coupler, any one have pictures or a diagram?
 
(quoted from post at 10:29:37 01/22/19) Thanks guys - I'm relatively new to servicing this John Deere B. I tried to find the dip stick to see if I could get an oil level and look for glitter, but couldn't locate it.

As for removing opening the crank case and inspecting the bearings and coupler, any one have pictures or a diagram?

The oil is checked with an oil level test plug low down on the RH side of the tractor just behind the cylinder block.

You can download the parts catalog, complete with parts drawings (.pdf) at the link below, you'll need to purchase a shop manual if you'll be tearing into it.

Here's a drawing of the oil pump, coupler is Key # 18.

For reference, looking up at the underneath of the tractor, you can see the bottom of the oil pump cover, Key # 32, near the oil filter bottom cover, Key # 15.

2hgqlpd.jpg


http://jdpc.deere.com/jdpc/JDPC/attachments.jsp?associatedPc=PC0330.pdf
 

Thanks Bob! Just so I understand, removing the Oil Pump items here from the underside will let me see the condition of the coupler and rod bearings?

I'm assuming the first step is to drain the oil which will let me see how much if any was in there.

Finding out that an oil dip stick is not provided makes me feel better as I wasn't able to locate it. Unfortunately, I'm sure there are quite a few bolts on the right side of the tractor in the area around the cylinder block. I'm definitely not trying to be needy, but how do I know which one? I presume I also fill through this hole until it pours out?
 
Do not remove the oil pump parts from below just yet. There is a cover on top of the engine crankcase. Remove this first and visually look in and see if the coupler is there. JD makes a GREAT service manual that covers the B models. It is a must have for any B owner.
 
(quoted from post at 11:37:37 01/22/19)
Thanks Bob! Just so I understand, removing the Oil Pump items here from the underside will let me see the condition of the coupler and rod bearings?

I'm assuming the first step is to drain the oil which will let me see how much if any was in there.

Finding out that an oil dip stick is not provided makes me feel better as I wasn't able to locate it. Unfortunately, I'm sure there are quite a few bolts on the right side of the tractor in the area around the cylinder block. I'm definitely not trying to be needy, but how do I know which one? I presume I also fill through this hole until it pours out?

You need to take the top cover off of the crankcase and check the coupler from there, the oil pump body can't drop out downward until the oil lines are detached from it from above, and you can check the coupling without any of that.

Coupling can be replaced by undoing only the bottom COVER of the oil pump, so the gear and shaft can drop down to allow the coupling to be installed.

Having a helper makes things a LOT easier!

To check the oil, look at the 0:46 mark of the linked video.

https://youtu.be/ix5tWbdHq3I
 
SM2004 is the manual number. not sure who sells a good reprint ? mine came from Deere years ago.
 
To change that coupler, you can remove the oil pump cover bolts and replace them with longer bolts, then the gears won't drop out and you can do it by yourself.
 
(quoted from post at 11:37:37 01/22/19)


Finding out that an oil dip stick is not provided makes me feel better as I wasn't able to locate it. Unfortunately, I'm sure there are quite a few bolts on the right side of the tractor in the area around the cylinder block. I'm definitely not trying to be needy, but how do I know which one? I presume I also fill through this hole until it pours out?

The YouTube link provided shows where the check plug is located. The attached photo also shows it. This is on an A, but your B will be similar.

As far as filling it, there should either be a cap on top of the main case near the pulley that you take off, or on some tractors you remove the crankcase breather and fill it there. On the A in this picture you unscrew the large cap to the left of the distributor.

As an aside, if you don't know where things like this are located, you need to get an owner's manual!


mvphoto30282.jpg
 
Thanks for the pictures!

I've ordered a manual and it is on its way.

I hoped that maybe it just got a bit warm and the continued cold would free the motor up, but no luck.

My first course of action will be to remove the crank case cover and have a peek. I'll follow up here when I get that done! Thanks to all for so much for your help!
 
The weather warmed up today so I removed the crankcase cover and did a little investigation.

From top of crank case:

mvphoto30835.jpg


I used my inexpensive "boroscope" to peek around. I couldn't find any linkages besides the piston rods and some oil lines around the main bearing area. That means I didn't inspect the oil pump coupler due to being unable to locate it.

I also was able to verify that the crankcase was sufficiently filled with oil as I was able to get a steam from the test bolt identified earlier.

Some more images:

Flywheel side cylinder:

mvphoto30836.jpg


Clutch side cylinder:

mvphoto30837.jpg
 
(quoted from post at 13:06:29 01/22/19)
You need to take the top cover off of the crankcase and check the coupler from there, the oil pump body can't drop out downward until the oil lines are detached from it from above, and you can check the coupling without any of that.

Coupling can be replaced by undoing only the bottom COVER of the oil pump, so the gear and shaft can drop down to allow the coupling to be installed.

Bob, as you can see, I took the cover off but was unable to locate the coupler or shaft or anything pertaining to the pump. Even with the SM2004 manual, I am a bit apprehensive tearing into things... Not quite sure where to go from here...
 
There's a shaft driven off the camshaft that goes down to the oil pump. Find the cam and follow that shaft going down to the pump
 
Is the pump drive shaft actually in the crankcase as I interpret from Figure 60-30-1? I was not successful in locating it during my last investigation.
 
(quoted from post at 09:01:36 02/05/19)
(quoted from post at 13:06:29 01/22/19)
You need to take the top cover off of the crankcase and check the coupler from there, the oil pump body can't drop out downward until the oil lines are detached from it from above, and you can check the coupling without any of that.

Coupling can be replaced by undoing only the bottom COVER of the oil pump, so the gear and shaft can drop down to allow the coupling to be installed.

Bob, as you can see, I took the cover off but was unable to locate the coupler or shaft or anything pertaining to the pump. Even with the SM2004 manual, I am a bit apprehensive tearing into things... Not quite sure where to go from here...



There's a vertical shaft passing between the connecting rods.

At it's top is a gear that meshes with gear teeth in the center of the camshaft, at it's lower end, beneath the level of the crankcase oil and on top of the oil pump is the square coupler that commonly breaks if the oil pump is frozen or otherwise stuck.

(The bottom end of the oil pump drive shaft and the top of the oil pump shaft are machined square, and the coupling is a small, square cast part square inside that connects the two shafts.)

Drain the engine oil, then look for the broken coupling to be lying on top of the oil pump. (Or sheared or missing.)

That's what I'd do first, verify if the coupling is actually broken, if it is, you will know for sure that the rod and main bearings were starved for oil and one or more has seized.
 

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