L35 TLB Won't Move

LukeWilson

New member

Equipment
L35
Dec 20, 2020
6
4
3
Ottawa, ON
Hi all,

I recently purchased a 1999 L35 with the GST transmission and ~3000hrs on it as I was looking for something smaller and more reliable than my clapped out old Case 580CK, unfortunately that plan isn't working out too well....

I've put about 25-30 hours on the tractor since I purchased it, the previous owner had receipts showing the hydraulic fluid had been changed about 100hrs before I bought it with Kubota UTD and a new filter.

About 3-4 weeks back just as the weather started to cool off, I noticed that if I let it idle in neutral to warm up at all, the tractor wouldn't move when I went to use it. The same thing would happen if I left the tractor idling in neutral for more than ~30 seconds. If I started the tractor and started driving right away, it would be fine. If it wouldn't move, I usually just shut it off for 10-15 minutes and it would be fine when I restarted it. I did a bunch of reading here as others have had the same problem, usually it seems to be an air leak on the suction side causing the pump to lose its prime.

Today, I went to move the tractor and got nothing, I've since tried it 3 more times over the day and still nothing. Never done that before. I did notice a couple of differences in how it acted though. The power steering seems to be working, usually it isn't. This seems strange as I believe its run off the same pump? When releasing the clutch in either forward or reverse, it seems like the machine is trying to move, I can see the wheels twitch when the clutch is let out.


A couple of other things to note that I've seen asked in other posts for the same issue:
-the hydraulic fluid is right up the top of the mark on the dipstick
-the PTO does work, I currently have a snowblower hooked up to it
-it seemed like the mechanical clutch was holding fine before today as it was possible to stall the tractor out or have it lug going up a hill in too high of a gear
-I did notice a drip hanging off the suction tube on the bottom of the transmission housing, I'm guessing this o-ring may be the culprit of the air leak, but I'm a little stumped as to why the power steering would work but the machine still won't move.

I will order a WSM manual tomorrow morning, unless anyone has had luck with any of the manual websites such as kubotamanual.com? I'm hoping I can get it before Christmas as I have 10 days off. I'll also order a 500, 1000 & 3000psi gauge with a 1/8" flexible grease hose as per North Idaho Wolfman's recommendation and start checking pressures.

I know it's not a new tractor by any means, but I'm pretty bummed that I'm having issues already. It also has an aftermarket cab on it, which will definitely make it even less fun if I need to split the tractor. Does anyone have any thoughts on what may be going on here or other things I should be looking out for?


Many thanks in advance,
-Luke
 

North Idaho Wolfman

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Sandpoint, ID
Yea your Number 1 check is going to be the pressure to the GST valves.
And yes your right the PS and the GST share the same pump section, but they have different feeds after the pressure regulator.
 

PoTreeBoy

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Lifetime Member

Equipment
L35 Ford 3930
Mar 24, 2020
1,067
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WestTn/NoMs
I've never found the L35 WSM except to purchase hard copy. Your dealer may be able to download. Check your conversations. Good luck.
 

LukeWilson

New member

Equipment
L35
Dec 20, 2020
6
4
3
Ottawa, ON
Thanks for the emails PoTreeBoy! My local dealer is also sending me a PDF copy of the manual as well.

Looks like the manual is referring to an adapter that is threaded into the pressure checking ports. Is this just a 1/8" NPT connection? Just want to make sure I don't need a metric adapter or something before everything closes for the holidays.

Started the tractor again today as its a little warmer and no change. So much for relaxing over the holidays...

-Luke
 

PoTreeBoy

Well-known member
Lifetime Member

Equipment
L35 Ford 3930
Mar 24, 2020
1,067
417
83
WestTn/NoMs
Thanks for the emails PoTreeBoy! My local dealer is also sending me a PDF copy of the manual as well.

Looks like the manual is referring to an adapter that is threaded into the pressure checking ports. Is this just a 1/8" NPT connection? Just want to make sure I don't need a metric adapter or something before everything closes for the holidays.

Started the tractor again today as its a little warmer and no change. So much for relaxing over the holidays...

-Luke
I think you'll find those to be BSP, which is the metric. You may find 1/8 male BSP x 1/8 female NPT adapter at auto parts or hydraulic store. I see them on Amazon, etc.
 

LukeWilson

New member

Equipment
L35
Dec 20, 2020
6
4
3
Ottawa, ON
I had a chance to check the pressures as per the manual today. The 3 plugs on the GST valve are pretty easy but the one on the regulator valve assembly was a real pain.

GST System Pressure: Measured ~395psi, spec is 356-370psi

Relief Valve Setting Pressure: Measured ~420psi, spec is 412-427psi

Pilot Pressure: Measured ~380psi, spec is 356-370psi

Clutch Pack Pressure: Measured ~50psi, spec is 356-370psi



So clearly the clutch pack pressure isn't what it's supposed to be, however it does drop to zero and come back up shifting 1-8 gears and forwards to reverse. Stays at 0psi when in neutral. The manual is saying to check the modulating valve, clutch valve and clutch pack. Some of the reading I've done says that there were some issues with the snap rings on the clutch packs, wondering if this may be the issue?

Anyone have tips on removing the GST valve? I'm a little worried about lining stuff back up when it goes back together, the pictures in my manual aren't very clear.

I also noticed that my power steering wasn't working today, seems a little strange that the GST system pressure is good but the power steering doesn't work?


More to come,
-Luke

-Luke
 

PoTreeBoy

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L35 Ford 3930
Mar 24, 2020
1,067
417
83
WestTn/NoMs
Did you have to find a BSP adapter?

I can't be of much help. Sounds like a clutch pack/seal issue.

One thing that's nagging me is the steering issue. Did you check it at 2000 - 2200 RPM or so? You either have 2 issues or the 2 are related. In the transmission troubleshooting table, one of the first questions is whether the steering is affected. If so, it directs you to check the pump. Do you have the means to check the steering pressure? I'm just trying to eliminate everything else before splitting the tractor.

Hopefully NIW or someone else more knowledgeable than me will be by shortly.
 

lugbolt

Well-known member

Equipment
ZG127S-54
Oct 15, 2015
3,774
871
113
Mid, South, USA
low clutch pack pressure is "usually" caused by either a failing clutch piston seal(s) OR the snap ring has broken out of the clutch pack housing. If you remove the valve body from the side of the transmission you can see the clutch pack. If the snap ring is broken out, the pressure plate and clutch plates are usually just laying loose, and generally there'll be a the pieces of broken clutch housing laying underneath the pack assembly. With that said it's not a fun job to remove the valve body assembly but it comes out in order to split the tractor anyway-or at least I take it out. Have only seen this a handful of times.

The original L35 clutch pack assembly was superceded a long time ago to a newer style which is a little tougher, so if it were me doing this job, I'd remove the valve body and have a look. If it's broken which I suspect it probably is based on the pressures, split it and replace the entire clutch pack assembly with the new part number which is the ONLY part number listed on the illustrated parts list. They no longer sell the old style.
 

LukeWilson

New member

Equipment
L35
Dec 20, 2020
6
4
3
Ottawa, ON
PoTreeboy, I used a 12" long grease gun hose that had 1/8" NPT connections on both ends. I had to step one end up to 1/4" npt to thread in the gauges I had and the other went directly into the ports on the transmission. In my experience any fittings 1/4" and smaller are "interchangeable" between NPT and BSP, I know there is a slight variation on the thread form but you can "get away with it" on the smaller sizes.

The main issue with accessing the port on the regulator valve was that it points to the back of the tractor, so an elbow is needed. Access is a little tricky there due to the loader frame and suction lines going to the hydraulic pump.

I didn't check the clutch pack pressure at anything other than idle. I did get a 3000psi gauge, so I'll have to take a look at see what the procedure is for checking the steering pressures.

Lugbolt, good to know I'll be able to take a look at the clutch housing before splitting. I'm a little stumped about the power steering, but one thing at a time I guess. I'll plan to pull the GST valve body next and take a peak.

Something else I've forgotten to mention is that the tractor is stuck in 4wd, the lever doesn't do anything and doesn't even feel like it's connected to anything. It's been like this since I've bought it and apparently as long as the previous owner had it as well. I doubt it's related, but figured I'd mention it. If I do end up having to split the tractor, I'll get this sorted out while it's apart. Seems like a pretty simply linkage from the parts diagrams, so I'm hoping for a sheared roll pin or broken linkage.


Thanks all,

-Luke
 
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LukeWilson

New member

Equipment
L35
Dec 20, 2020
6
4
3
Ottawa, ON
I managed to wrangle the tractor into the workshop today, of course we got 6" of snow last night to add to the fun... The power steering worked fine while I was towing the tractor around. Seems like all signs are pointing to a hydraulic clutch issue.

I pulled the GST valve body off, I guess the good news is that it doesn't appear that the snap ring has failed. I didn't see anything that looked broken or out of place. No signs of metal fillings or nasty looking hydraulic fluid either.

The manual is saying the modulating valve and clutch valve are the other potential spots to look at. The modulating valve doesn't look too bad to take apart, but I think I have to split the valve body to get to the clutch valve. I'm a little afraid of the check balls and springs going flying and not knowing how to put it back together. Has anyone taken the valve body apart and have any words of wisdom?

If I can't find anything with the valves, I think I have to assuming there is an issue with the clutch piston seals as Lugbolt has mentioned. Was really hoping I'd find something obvious, but nothing so far.

-Luke
 

LukeWilson

New member

Equipment
L35
Dec 20, 2020
6
4
3
Ottawa, ON
Figured I would post an update as I believe I got this fixed. Big thanks to North Idaho Wolfman for all the help.

I ended up splitting the tractor as I couldn't find any other issues that would cause the low clutch pack pressure. Once I split it, I found that one of the seal rings for the clutch pack seemed to be in the wrong place:

1612407844681.png


My theory is that as long as the seal remained pushed up against the right side of the wide groove, it would function as it should. If it shifted to the left though, all the hydraulic pressure would just dump back into the transmission case resulting in the low pressure I was seeing. I don't see how the seal could have moved other than being assembled incorrectly at some point in the past.

I ordered new seals for the clutch pack, as well as a rear main and input shaft seal as it looked like something was weeping into the bellhousing. I also replaced the 4x4 shift fork while I had it split as it had been bent/worn and wouldn't catch on the gear to disengage front wheel drive.

It's a real pain putting the GST valve body back on, the little rubber covered steel tube that feeds oil pressure to the clutch pack was tricky to line up. Once I got it together enough to test, it seems to work as it should with the rear wheels jacked up. I do find the pressure a little slow to come back up after a gear change (about 5 seconds to hit 380psi), but I'm thinking this may be related to cold fluid as it's currently -20C/-5F outside. I'll report back once I can get the machine up to operating temp.

I found that the body panels were in worse shape than I thought, I'm going to sandblast and repaint everything before I put the rest of it back together. Going to do a full machine fluid flush and hope that I can put some hours on it before any more trouble!

Thanks for everyone's help, it was a little daunting to split the machine, but really not that bad once you get into it.

-Luke
 
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