John Deere B loses power after running for several minutes

pmarkel

Member
I have noticed a significant loss of power in my 1948 John Deere B over the last several months. I had used it to pull out logs and push snow last winter and it had plenty of power. However, this summer I noticed that the tractor would stall under load. When I sank the cultivator (7 ft ferguson 3 pt cultivator, not a chisel) the tractor would come to a stop. The engine wouldnt shut off and it wouldnt labor, but it simply was stopped dead. So I rebuilt the carb which had some rust and dirt inside and the main nozzle had two clogged holes. However, I encountered the same loss of power this morning. Again, I was using the cultivator to stir up some soil in the garden to plant a cover crop. The tractor ran fine for several minutes sinking the cultivator to the desired depth. However, after about five minutes of work, the tractor would simply not pull the cultivator any longer. Could this indicate a deficient magneto coil or low engine compression? Any advice is welcome.

Sincerely,

Peter Markel
 
From what you described it has a slipping clutch.
"The engine wouldnt shut off and it wouldnt labor, but it simply was stopped dead. "
 
So does it stall or does it just stop pulling but keep running?? If it keep running and not pulling I agree with Mike. If it stalls it could be weak spark or a carb problem.

You need to check your spark if it stalls lout and make sure you have a good blue/white spark that jumps a 1/4 inch gap or more.

Next make sure you have a good steady flow of gas form the carb drain plug that will fill la jar in less then 3 minutes
 
Thank you Mike. I definitely notice a difference between the clutch on the B and the one on my 60(which is more tight) and was actually going to tighten it up (or reline if necessary). But would clutch slippage present itself intermittently?
 
Thanks. "stall" wasnt the right wording on my part, it's not as though the engine rpm is being pulled down by the load or that it sounds like it is cutting out. It sounds fine but the tractor's forward motion stops. And there is some play in the clutch to be sure.
 

The clutch would need to be awfully loose to slip that easily...All of mine are only tight enough to get a light "Snap" when the clutch lever is all the way in and they don't slip..even when I have HEAVY loads on mine, they do not slip..I mean loads like a F-145 4x16" on a 630..

I wonder if he has a Clutch Bolt broken...that would cause this slippage.
 
(quoted from post at 12:33:46 10/13/16)
The clutch would need to be awfully loose to slip that easily...All of mine are only tight enough to get a light "Snap" when the clutch lever is all the way in and they don't slip..even when I have HEAVY loads on mine, they do not slip..I mean loads like a F-145 4x16" on a 630..

I wonder if he has a Clutch Bolt broken...that would cause this slippage.
ould that be difficult to fix? I popped the drum shield off today and tried to tighten the 3 bolts inside. The bolts were free, almost loose, but I could not get the clutch to tighten up while still having snap in the hand lever. And loose theres no snap either, the lever will not stay engaged properly.
 
(quoted from post at 16:20:54 10/13/16)
I popped the drum shield off today and tried to tighten the 3 bolts inside. The bolts were free, almost loose, but I could not get the clutch to tighten up while still having snap in the hand lever. And loose theres no snap either, the lever will not stay engaged properly.

Done wrong, you can have these results. To do it right, use a torque wrench and have the clutch engaged. Torque the three bolts to 15 ft lbs each and at least twice on each bolt after torquing the other two bolts. Now disengage the clutch, it should have some form of pop over. If it's tremendous then next time only torque to 10 ft lbs. If the pop over effort is weak then go to 20 ft lbs. Do this several times to get the bolts worked into their worn areas where they want to live in. To do this repeat procedure properly just back off the nut 1/2 turn and retorque it from there.

Previously you may have torqued it too much and not had enough muscle to pop it over out or in. It's somewhat confusing as to which it is until you have some experience at properly adjusting the clutch with a torque wrench. It should always be engage when adjusting with a torque wrench, you want to avoid the too tight scenario. A torque wrench is not absolutely required, but a lot of common sense is. I will always find and use my small torque wrench for this work.
 
(quoted from post at 02:31:19 10/14/16)
(quoted from post at 16:20:54 10/13/16)
I popped the drum shield off today and tried to tighten the 3 bolts inside. The bolts were free, almost loose, but I could not get the clutch to tighten up while still having snap in the hand lever. And loose theres no snap either, the lever will not stay engaged properly.

Done wrong, you can have these results. To do it right, use a torque wrench and have the clutch engaged. Torque the three bolts to 15 ft lbs each and at least twice on each bolt after torquing the other two bolts. Now disengage the clutch, it should have some form of pop over. If it's tremendous then next time only torque to 10 ft lbs. If the pop over effort is weak then go to 20 ft lbs. Do this several times to get the bolts worked into their worn areas where they want to live in. To do this repeat procedure properly just back off the nut 1/2 turn and retorque it from there.

Previously you may have torqued it too much and not had enough muscle to pop it over out or in. It's somewhat confusing as to which it is until you have some experience at properly adjusting the clutch with a torque wrench. It should always be engage when adjusting with a torque wrench, you want to avoid the too tight scenario. A torque wrench is not absolutely required, but a lot of common sense is. I will always find and use my small torque wrench for this work.
hanks Lee, I have previously adjusted the clutch on my 60 and that gave me no trouble so I was just concerned that the clutch on the B might need to be relined. Is there anyway to tell if it needs a rebuild short of taking off the pressure plate and inspecting the free facings?
 
Really, new facings are cheap, $20 to $25 for a pair. The only hard part is that you will need a puller for the driving disc to replace the back one but that is pretty basic stuff. Then you know what you have and will be good for years with the use you give it. It's possible that the T bolts are bad but they are cheap and easy to replace too. You may be able to get by without doing any of this, but the point I'm making is that redoing the clutch is cheap and easy unless you have an issue with a major part like the driving disc or something.
 
No real need for a puller. You can use two long bolts with square nuts through keyholes in the drive disc. 1/2 inch for the A, B is probably the same. There are ridges on the back side to grip the nuts. Then tighten the bolts. If the bolts alone don't pull it put the center bolt in and give it a pop with a hammer to break it loose. They're easy to figure out once the disc is off.
 
(quoted from post at 08:03:51 10/14/16) Really, new facings are cheap, $20 to $25 for a pair. The only hard part is that you will need a puller for the driving disc to replace the back one but that is pretty basic stuff. Then you know what you have and will be good for years with the use you give it. It's possible that the T bolts are bad but they are cheap and easy to replace too. You may be able to get by without doing any of this, but the point I'm making is that redoing the clutch is cheap and easy unless you have an issue with a major part like the driving disc or something.
hanks for the advice. I actually happened to adjust it properly today (probably by sheer dumb luck) and it has good snap in it. I guess I won't know whether it will remain tight until I give it some prolonged work.
 
You are welcome, no not really. NoDakInMN spells it out pretty much like it is. You'll have to get behind the clutch driver to really assess your current state of that last clutch disk in there. While you are in there that far, you might as well just replace it. Only way to do it right is get dirty. Don't forget to tend to that rarely greased bearing in there too.
 

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