# Deere 100 Series Questions



## FPMotorsports (Apr 1, 2015)

Afternoon folks, hows everyone been running?

Recently just came across a john deere las100 with about 600 hours on it. It starts fine, runs great for about 15-20 minutes than seems to lose power. It doesnt surge, and it apparently only started happening after a few cuts in the spring.

Any ideas of what this issue may be?! I have yet to do ANYTHING to it, i will start in the morning (to damn hot right now 36 celcius) 

What troubleshooting steps would you take?

Any and all recommendations are greatly appreciated!


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## geogrubb (Jul 28, 2006)

FPMotorsports said:


> Afternoon folks, hows everyone been running?
> 
> Recently just came across a john deere las100 with about 600 hours on it. It starts fine, runs great for about 15-20 minutes than seems to lose power. It doesnt surge, and it apparently only started happening after a few cuts in the spring.
> 
> ...


The fuel cap is probably clogged, try running it with the cap loose. Have a good one. Geo


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## 30yearTech (Sep 14, 2006)

What engine does this unit have?

If it's a twin cylinder engine, I would check to see if one of the cylinders is loosing spark when the engine gets hot. A twin running on 1 cylinder will loose a lot of power, but keep running.


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## FPMotorsports (Apr 1, 2015)

Yeah, its running a 21 HP briggs, twin cylinder. Its actually a really neat design. I am sure replacing the crank would suck but valve access and such is really really easy.

I took a look at it yesterday, theres lots of trimmings and things floating around the gas tank, the fuel filter is crammed full of things. The air filter and plugs were gross. The carb needs a good soak too. I will try these quick easy fixes first, than run it again for an extended period in order to see if there is still power loss.


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## 30yearTech (Sep 14, 2006)

Depending on the carburetor used on your engine, it's sometimes possible for one of the barrels feeding fuel to the cylinders to get clogged and only feed fuel to one cylinder. They operate independently of each other on some setups.


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## FPMotorsports (Apr 1, 2015)

*UPDATE:* Okay, so over the weekend I put in 2 new plugs, properly gaped. New air filters, new fuel filter (it was disgusting) I drained all the gas in the tank (there was a ton of leafs and things in there) Cleaned it, put fresh gas in. Did oil and oil filter. Cleaned all fins, cleaned everyone, checked hole in gas cap. Its certainly idling much better, it sounds better and has a bit more GO in it when just driving around but the issue from previous is still there.... 

What happens is that after 15-20 minutes of cutting, (actually using the deck, or under "load" so to speak) the motor loses almost all power. Does not shut off, but reverse becomes super slow mode reverse, and forward the same thing. 

Any recommendations?


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## 30yearTech (Sep 14, 2006)

can you tell if it's the engine loosing power, or is it just the motion drive that starts to suffer?


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## FPMotorsports (Apr 1, 2015)

Its not me riding it, a friend was complaining about issues. i told him to drop it off. Figured most of the things we replaced would do the trick. I ran it for about 30-45 minutes after it ran great. Drove up and down great. Didnt have anywhere to engage the blades and run it for a bit so he picked it up went to use it today and same deal.


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## 30yearTech (Sep 14, 2006)

It may be an issue with the transmission and not the engine.

If the problem is just with the motion drive and is not affecting operation of the blades, if the engine is running alright but the mower just moves slowly, then it's most likely an issue with the transmission.

Could be old transmission fluid, a plugged filter or low fluid level.


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## FPMotorsports (Apr 1, 2015)

Well when i get the time ill check those things for sure! Appreciate the looking out, thanks!


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## FPMotorsports (Apr 1, 2015)

Okay so, today I got the deck off and everything seemed fine there, mower belt looks a bit worn so ill change that just because. Now I have the deck off, and ive went under what should I be looking for? 

1. Is there a way to check the fluid in the transmission?
2. How can i tell if the drive pulley, or belt or any of the linkages are out of whack? They all seem tight and fine, the belt and brake so on seem good...
3. There is a electrical sensor or something of that nature plugged into the transmission, could this cause issues?!


What should i be looking for under the mower with regards to my problems?

Also Product Number on side of frame was: GX0120A044346 if that helps!


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## 30yearTech (Sep 14, 2006)

FPMotorsports said:


> Okay so, today I got the deck off and everything seemed fine there, mower belt looks a bit worn so ill change that just because. Now I have the deck off, and ive went under what should I be looking for?
> 
> 1. Is there a way to check the fluid in the transmission?
> 2. How can i tell if the drive pulley, or belt or any of the linkages are out of whack? They all seem tight and fine, the belt and brake so on seem good...
> ...


The *VERY FIRST* thing you need to do is *determine* if the problem is with the engine or transmission.

Once you know where the issue lies, then perhaps we can help you look at the possible reasons for the problem and where to look.


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## RKDOC (Jun 20, 2006)

You need to drive (run) the mower until it starts to slow down. Then you can see if it is the trans slowing or the engine slowing. If speed slows but engine keeps running then it is a drive problem. If the engine starts slowing then you have an engine problem. Good luck.


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## FPMotorsports (Apr 1, 2015)

I am presently driving it up and down the back lane in an attempt to recreate the problem! will keep posted!


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## FPMotorsports (Apr 1, 2015)

Completely lost now. Now the effin thing wont start. I have DONE NOTHING to this mower since it arrived here friday except remove the deck. After that it wont start, i had disconnected the battery and now it doesnt start. It has to be boosted so any ideas there?

It also will stall the minute you press down on reverse. Now the steering weel appears to be jumping gears down the shaft when you try and turn the tires. 

Like I can fix cars, atvs, snowmobiles but im about ready to roll this Deere into Deere because im completely fu%#^#d here.


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## 30yearTech (Sep 14, 2006)

FPMotorsports said:


> Completely lost now. Now the effin thing wont start. I have DONE NOTHING to this mower since it arrived here friday except remove the deck. After that it wont start, i had disconnected the battery and now it doesnt start. It has to be boosted so any ideas there?
> 
> It also will stall the minute you press down on reverse. Now the steering weel appears to be jumping gears down the shaft when you try and turn the tires.
> 
> Like I can fix cars, atvs, snowmobiles but im about ready to roll this Deere into Deere because im completely fu%#^#d here.


Since you removed the deck, there is probably not enough tension on the pto lever to engage the safety interlock switch. The safety circuit "thinks" the blades are engaged. 

This will prevent the starter from working and will kill the engine once started whenever the operator gets off of the seat, or tries to operate in reverse.


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## FPMotorsports (Apr 1, 2015)

Okay yeah, well that was what was happening as well as the fuse being blown. So the motor is starting each time now again. No problems there, the issue with turning right is the teeth on the plate bolted to the bottom on the right turn side are worn completely off. That seems like an easy fix. 

Now i ran the mower for an hour PLUS. And cant seem to recreate this guys issue. I am presently uploading a video i made showing all the under workings and such so perhaps when that is ready yall can watch it and see if you can notice or hear anything of note.


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## FPMotorsports (Apr 1, 2015)

Heres the video!

https://youtu.be/TuGeGKnMCiQ


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## 30yearTech (Sep 14, 2006)

FPMotorsports said:


> Heres the video!
> 
> https://youtu.be/TuGeGKnMCiQ


All in the video looks good, did not notice anything unusual. *If *the problem is in the transmission, it would likely happen when the fluid gets hot. When the oil gets old and heats up, it will sometimes foam and the air bubbles will cause the transmission to slip and even sometimes stop working. It could also have been a sticking piston or valve that has freed up and is no longer an issue. 

Engine sounds real good too!


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## FPMotorsports (Apr 1, 2015)

Yeah, like i said i did most everything to the motor when he brought it in initially, so i really feel like its running fine. When he brought it back i measured valve clearances and it was all nice and tight and proper. Everything was clean. 

So of course i discovered the steering problem and have to pick up that GX20052BLE tomorrow and fix that so i can go riding around in a field to try and recreate the issue. because i havent been able to recreate it after hours of running on the block.


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## FPMotorsports (Apr 1, 2015)

*UPDATE:*

Well I changed the steering sector and so thats all good to go. Cleaned and put the deck back on. Loaded it on the trailer.. took it to my buddies 2 acre lot to see if i can recreate the problem and sure enough, after 20 minutes or so of cutting the thing just starts crawling. There is no loss in RPM, the motor sounds the same, but after 20 minutes of mowing i began to lose all forward momentum, and reverse doesnt even want to work much at all, soo slow that it barely moves in reverse. 

Any ideas!? I have done so much i think you pros should be able to narrow this down at this point!


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## 30yearTech (Sep 14, 2006)

Well you have narrowed it down. The issue is with the transmission. It's not uncommon on these units as they get older. They do make parts for the transaxle, but very likely an oil change and possibly a new filter will take care of it for awhile.

Here is the rub, you have to split the case on the trany to service the filter, and changing the fluid without splitting the case is a real pain. None of your options are fast and easy unless you just replace the entire transaxle, but then that's expensive.


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## FPMotorsports (Apr 1, 2015)

Alright, transmission is out, its open its drained. Its really clean, no unnecessary movements, no natural disasters so to speak. Tomorrow ill refill it and see!

Any recommendations on what i should refill it with!?


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## 30yearTech (Sep 14, 2006)

Check with a John Deere dealer or the transmission mfg and see what fluid is recommended. Most likely a 20w50 or 15w50 oil, but I would check and make sure.
Once you have it full of new fluid and reinstalled, you will need to purge the air out of the system. Raise the rear wheels off the unit and cycle the unit forward and reverse several times to allow any air trapped in the unit to work it's way out. Hopefully there has not been any substantial internal wear in the unit that will prevent it from working properly with the new fluid.

Best of Luck...


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## FPMotorsports (Apr 1, 2015)

I appreciate all your help 30year. Seriously do buddy.

So the tufforq https://www.tufftorqservices.com/Env...DING OIL.pdf says that they recommend a 5W50 full synthetic....

Today i came home.. put a gasket on, filled it with new 5W50.. installed it. Instantly started making a grinding type noise... Pulled it back into the shop.. put it on stands. I also lost all power WITHOUT cutting, so zero load in about 5 minutes this time. Before it lost power the same way.. after 15-20 minutes of cutting..

When i turn A wheel the other turns opposite.. now im not a master mechanic but that seems not right. What I am saying is if i turn say the right axle forward.. the left axle goes backwards. And vice versa. So the tires are turning... opposite directions.

I didnt remove any parts of the transmission when i opened it.. just opened it checked the magnets for shavings, cleaned it real good let it dry over night. New gasket, new fluids. reinstalled..


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## 30yearTech (Sep 14, 2006)

FPMotorsports said:


> When i turn A wheel the other turns opposite.. now im not a master mechanic but that seems not right. What I am saying is if i turn say the right axle forward.. the left axle goes backwards. And vice versa. So the tires are turning... opposite directions.


That's the way it's supposed to work. That's the way the differential reacts when there is no load on it. Each wheel pulls independently of the other. The wheel with the least resistance is the one that drives the unit. This also allows the tire on the inside of a turn to rotate slower then the tire on the outside of a turn without any binding that would occur if the drive were utilizing a live axle.

If you were to jack up a pick up truck or any rear drive auto and rotate one wheel, the other would turn in the opposite direction, just like the tractor. 

Make sure the bearing on the input shaft is not loose, or when you reassembled that the input shaft was properly inserted into the pump drive and is not in a bind.

Best of Luck...


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## FPMotorsports (Apr 1, 2015)

Ah, I suppose I just never considered spinning a wheel off the ground. All the ATVs ive done have used independent suspensions. First real "solid" axle. 

Anywho, the internals look real clean. I didnt remove anything but the collecting magnets. This time I have done a pile of research, https://www.youtube.com/watch?v=YDjhAo6aZ7s has been a very helpful series of vids. So when i get situated (just got back from camping) and the shop is clean and organized ill get back at it. 

Ill have to check the pistons, the pump. Ill gopro it being disassembled, and reassembled. It makes for forgetting anything for easy. I take a lot of pictures as I go as well, just as this is a new project for me, so the first time over ill learn a pile, remember a pile. And be good to go in the future.


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## FPMotorsports (Apr 1, 2015)

*UPDATE TIME:*

Well folks, after it sitting in my garage under a bed sheet for a month my friend decided to order up the tuff torq rebuild kit (1A646099590) It contained a new center case, motor, pump, all pistons, orings, seals, even gasket maker. So, I pulled it all apart again (3rd time), this time I removed everything, all the internals. Layed them out, cleaned everything thoroughly and went ahead with the rebuild kit. New oil, installed. Runs like a banshee. Cant even keep up to her now. She jerks ya back good and hard when ya press on the peddle.

Very happy to report, that its been two weeks since the rebuild (I wanted to wait before updating, dreading that I would get a text any minute saying "hey buddy, bad news" haha) and everything is still working totally fine!

Thanks everyone for all the recommendations, for all the help and suggestions. You can consider me very well versed in the removal, rebuild, understanding, and reinstallation of the K series hydrostatic tuff-torq transmissions!


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## 30yearTech (Sep 14, 2006)

Glad to hear you got it working again, and got some valuable experience to boot! :thumbsup::thumbsup:


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