Mysterious Carb problem with early unstyled B

[John R in Wisconsin]

I have a 1937 John Deere B with a DLTX10 carburetor. It was running funky so I removed the carb, disassembled it, and soaked it and all small parts in carburetor cleaner. I blew out all openings with compressed air. I replaced key parts with a new carb kit from Steiner Tractor, and put everything back together, and adjusted it as recommended in the instructions that came with the kit. The tractor started fine after the rebuild, but now for some crazy reason the engine will not shut off or even slow down much when the throttle lever is pulled all the way back, and the throttle lever assembly on top of the carburetor is pulled all the way back against the throttle stop pin. How can this be? I took the carb back off the tractor, looked inside, and the butterfly closes completely when the throttle shaft is rotated so the lever assembly on top of the carb is rotated against the stop pin! I don't see how the engine can keep running when the throttle disk is completely closed!! See photo.

Help! Any ideas?

 

[susandiane]

I'm not trying to be cute, but did you get the butterfly on the shaft right? If it's backwards, the butterfly won't seal the intake even it's closed completely. Don't ask me how I know!

 

[buckeye al]

Did you maybe press in new throttle shaft bushings with your kit?

The bushings need to be pressed in until their inner ends are flush with the INNER diameter of the main bore of the carb. If not air passes around the plate between the shaft and the bearing bore. The mix can usually be adjusted to make it run but it runs too fast because of the air bypassing the plate. It's basically an internal vacuum leak. Not saying that's it but it's a possibility I've encountered.

Hope that helps.

 

[John R in Wisconsin]

Buckeye Al - I did press in new brass bushings, but I did not know they had to go in to a certain depth! I will check this. Thanks.

 

[John R in Wisconsin]

Susandiane - I am quite sure that I got the butterfly on the shaft correctly, because I took a photo of the butterfly before I took it apart. But thanks for the suggestion!

 

[old]

With at closed all the way it works on the idle circuit of the carb so it should stay running just at low RPM. On my 1935 JD B at idle you can almost count how many times the flywheel rotates

 

[buckeye al]

I set them so they're just a bit proud in the main bore then dress them 'till they match the bore with usually chain saw files. I shy away from using a burr for fear of a slip that makes any big gouges any place. I don't go until they're proud at the sides, but only at the crown & invert. Probably a bit excessive on my part because Marvel didn't likely go this far when they made 'em & likely dealers didn't when they re-built 'em but they do need to get close to the plate. Pressing them to that point is good enough. The top one is a bit shorter than the bore it goes into because it is supposed to be recessed at the top for the felt or seal around the shaft. I've seen kits where a lipped type rubber seal was installed but was so tight the governor action was all messed up. Felt & regular application of a drop of oil fixed that one.

Good luck.

 

[Mike(NEOhio)]

Did you replace the butterfly? They will wear on the bottom so that they settle and leave a gap at the top of the bore. The new bushings need to be pressed in to fill where the hole meets the bore, then filed to flush with the bore. Per RandyB's instructions.

 

[Kris1946A]

(quoted from post at 18:03:20 10/24/21) Did you maybe press in new throttle shaft bushings with your kit?

The bushings need to be pressed in until their inner ends are flush with the INNER diameter of the main bore of the carb. If not air passes around the plate between the shaft and the bearing bore. The mix can usually be adjusted to make it run but it runs too fast because of the air bypassing the plate. It's basically an internal vacuum leak. Not saying that's it but it's a possibility I've encountered.

Hope that helps.

Hey guys, thanks for this post - I just took the carburetor apart on my 1946 A, and I did not press the bushings down to the main bore of the carb. I'm having similar problems with the engine running way too fast. I'll press them down further and see how it works out. A related question for you - Ever since I put the carb back on, I've had issues with the tractor being sluggish when putting it into gear. I've played with the load pin, but that doesn't seem to help. Would too much air getting by the carb cause the tractor not to move when put in gear? Or do I have a clutch problem now too? Thanks for your help!

 

[Mike(NEOhio)]

Sluggish how? Engine weak or engine running but not moving. Load pin?? You mean load needle? Trying to help but you're a little vague.

 

[ArnieinChesterfieldVa]

If you don't have luck solving the problem, Mike(NEOhio) works on carbs in his shop & does tremendous work for a fair price.He was one of the repliers to this post. Mike did my 60 carb about 5 years ago & it was well worth it.
Arnie

 

[Kris1946A]

HI Mike, thanks for the response. Yes, I mean the load needle. The engine is running but not perfect because I don't think I have the carb right. The engine is running at what seems to me very high RPMs based on the sound and how fast the flywheel is spinning. When I say it's sluggish, I mean that when I put the tractor in gear and push the hand clutch forward, the tractor doesn't move. The belt wheel tries to spin but moves about an inch and stops. If I take the tractor out of gear, then engage the hand clutch, the belt wheel moves very slowly then starts spinning forward. I tried to adjust both the load and idle needles, but neither seems to make a difference. I did not have this problem until I took the carb off, cleaned it, replaced gaskets, bushings, etc. So, I'm wondering if this could be the tractor getting too much air and not enough fuel. It seems weird to me that the engine would run at such high speed but not have the muscle to move the transmission. Any thoughts are appreciated! Thanks!

 

[NoDakInMN]

(quoted from post at 21:06:41 10/26/21) HI Mike, thanks for the response. Yes, I mean the load needle. The engine is running but not perfect because I don't think I have the carb right. The engine is running at what seems to me very high RPMs based on the sound and how fast the flywheel is spinning. When I say it's sluggish, I mean that when I put the tractor in gear and push the hand clutch forward, the tractor doesn't move. The belt wheel tries to spin but moves about an inch and stops. If I take the tractor out of gear, then engage the hand clutch, the belt wheel moves very slowly then starts spinning forward. I tried to adjust both the load and idle needles, but neither seems to make a difference. I did not have this problem until I took the carb off, cleaned it, replaced gaskets, bushings, etc. So, I'm wondering if this could be the tractor getting too much air and not enough fuel. It seems weird to me that the engine would run at such high speed but not have the muscle to move the transmission. Any thoughts are appreciated! Thanks!

OK, first things first.

1.When you engage the clutch, does the motor pull down when the tractor tries to move or does it maintain speed?

2. When you engage the clutch with the tractor out of gear, does the motor pull down or does it maintain speed?

If the motor maintains speed but the tractor doesn't move or the pulley is slow to turn when the tractor is out of gear, then the issue is not the carb, at least for this issue. Your clutch is loose and needs adjustment.

3. If you try pulling the tractor in nuetral with another vehicle, does it roll freely?

If it does not, then your brakes may be sticking which could lead to your clutch becoming loose with unnecessary wear.

If the tractor rolls freely, and the motor pulls down when the clutch is engaged, in gear or out, then you may have a carb issue.

4. What position is the throttle in when you say the motor is running too fast?

If it is running to fast at idle, then your problem may the carb, governor/throttle linkage or the governor itself.

You are there, we are not, so for us to help, we need to know as much of what is going on as possible. A tachometer reading of engine speed and at what throttle setting, would be useful as well.

 

[Kris1946A]

Oh my gosh, thank you so much for these questions! And help! I really appreciate it.

I'll answer them below.


OK, first things first.

1.When you engage the clutch, does the motor pull down when the tractor tries to move or does it maintain speed? [b:cd436f621c]****the engine maintains speed[/b:cd436f621c]

2. When you engage the clutch with the tractor out of gear, does the motor pull down or does it maintain speed? [b:cd436f621c]****yes, it maintains speed.
[/b:cd436f621c]
If the motor maintains speed but the tractor doesn't move or the pulley is slow to turn when the tractor is out of gear, then the issue is not the carb, at least for this issue. Your clutch is loose and needs adjustment. [b:cd436f621c] ****that makes me think it's a clutch issue. [/b:cd436f621c]

3. If you try pulling the tractor in nuetral with another vehicle, does it roll freely? [b:cd436f621c]***Haven't been able to try this yet - hoping to over the weekend if it stops raining.[/b:cd436f621c]

If it does not, then your brakes may be sticking which could lead to your clutch becoming loose with unnecessary wear.

If the tractor rolls freely, and the motor pulls down when the clutch is engaged, in gear or out, then you may have a carb issue.

4. What position is the throttle in when you say the motor is running too fast?

If it is running to fast at idle, then your problem may the carb, governor/throttle linkage or the governor itself. ***

You are there, we are not, so for us to help, we need to know as much of what is going on as possible. A tachometer reading of engine speed and at what throttle setting, would be useful as well.[/quote] spoke to a friend that is a collector a couple of days ago. He told me he though the clutch was probably slipping and a separate issue from the carb. But, he hasn't seen it either. I'll

Another thing he asked me about the carb was if the throttle moves freely in the carb or if the bushings are tight and restrict movement. I did notice that the bushings were quite tight when I put the pin back through them. He suggested that I hone the bushings a bit to loosen that up. I think I'll give that a try too.

Thank you so much for your input - I really appreciate the help! I'm new to trying to fix these old machines up![/b:cd436f621c][/b]

 

[NoDakInMN]

You picked a good machine to learn on. Mine was a 1937 unstyled A.

Yes, a sticky throttle shaft would cause some engine speed issues.

I would seriously consider getting a service manual for your tractor. A parts manual is useful as well, not just for the parts listings, but the exploded diagrams show how things go together. While I'm at it, Roberts Carburetor Repair has an excellent video on the DLTX series carbs, their service and repair. And of course, there is a lot of information on You Tube.

 

[John R in Wisconsin]

Hi all - I am the person who started this thread, and I am happy to report that my carb problem on my 1937 B is solved. I followed the advice of a couple of helpful folks on this forum, and tapped the new throttle bushings into the inner bore of the carb, and then filed them to allow the butterfly to turn freely. The tractor now runs great, but the true test will be when under load next summer when I am raking hay with this old beauty. Thanks all!