Cub Cadet 3000 Series Tractor Problems

[veegee2]

I have two Cub Cadet 3000 series tractors. The first one I bought was a Model 3240. While I was using it to blow snow the driveline froze up and I could not move either forward or backward. Since I was not prepared to tear down this unit or send it to a local repair shop I bought a used Model GT3200 from a Cub Cadet Dealer who claimed that it had been fully serviced and was ready to go.

I transferred the front hitch from the 3240 to the GT3200 and have been using the GT3200 ever since to mow, haul, and blow snow. The 3240 has been parked in my shed waiting for a future repair.

I saw a used Hydrostatic Transmission/ Differential that was compatible with my 3240 on eBay that was described as a working unit removed from a tractor with an engine problem. The seller guaranteed the unit to work as it should so I bought it to install in my 3240 tractor.

It took some time for it to arrive by freight so in the meantime I started searching some Cub Cadet forums and I found out that the 3000 Series tractors had a serious problem of the four 3/8 x 2.25 long bolts loosening up, backing out, and interfering with other components inside the differential. Just to make sure the Hydrostatic Transmission/ Differential that I had just bought didn’t have this problem I bought a borescope and peered inside the differential through the dipstick hole. I could not see the location of the bolts but I did see small metal shards and I knew this meant trouble so I opened the differential for further inspection.

Sure enough some of the 3/8 x 2.25 long bolts had come loose and backed out of their holes far enough that the bolt heads contacted the bevel gear and chipped some teeth on it. About half of the bolt head was also worn away.
I completely disassembled and cleaned the differential and replaced the bevel gear with a new one. I bought new 2.75 inch long grade 8 bolts, applied thread locker to them, and added a lock nut where they now protruded through the 60 tooth Spur Gear and I reassembled everything back together and installed it into my 3240 tractor. I installed a new Cub Cadet Hydraulic Filter and filled the differential with fluid.

I had already inquired at the local Cub Cadet dealership if the air needed to be purged from the system after a repair such as I performed and they said “yes” and gave me the following instructions:

“To purge the system; raise the rear wheels off the floor using jack stands making sure the rear tires are just off the floor, about one inch. Block the front wheels so the tractor will not slip and fall off the stands. Start the engine and run at idle speed and repeat opening and closing the bypass valve (towing) and alternately press the forward then the reverse pedals for about one minute. When the wheels start to move instantly increase the engine speed. Use the forward and reverse pedals to make quick starts and panic stops for about one minute. Turn off engine and remove the tractor from the stands. Check the fluid level and add if needed. Start the engine, turn the steering wheel back and forth for one minute. Drive the tractor around a little while turning the steering wheel back and forth and raise and lower the deck a few times also. Park the tractor on a level spot and check the fluid level again and add if needed. You should be good to go. After you have used your tractor for some time, park it on a level spot and check the fluid again and add if needed.”

I performed this procedure numerous times but I was not able to get the wheels to turn. I opened the three ports on top of the Hydrostatic Transmission and filled them with oil and still no change. I removed the return line from the charge pump and applied air pressure to the differential sump through the Dipstick hole in an attempt to force the fluid through the system but this also did not work.

I did more online research which led me to suspect that the Gerotor in the charge pump might be damaged. I opened the charge pump by removing the two bolts and examined the Gerotor and the mating parts and they all appeared to have no damage.

Not knowing where to go next I decided to open up the original 3240 differential and see why it quit working. I found the same problem with it as the one that I had purchased on eBay so I repaired it and put it back in the 3240 Tractor. I thought I would have to go through the air purge procedure with it but I was surprised that the wheels began to turn as soon as I started the engine and depressed the drive pedals.

Now that I had a 3000 Series tractor working I decided to open the GT3200 Differential to see if it was okay inside even though I had no signs of drive trouble, however the Differential Lock never worked correctly on this tractor so I planned to fix it at the same time. I also wanted to install the longer bolts and lock nuts in it to prevent any future problems with bolts backing out.
Examination of this differential revealed that the bolts were still in place and they had a thread lock compound on them which apparently was the Cub Cadet fix for this problem.

The problem with the Differential Lock was it was not adjusted right by someone and the Actuator Shaft Fork was constantly rubbing on the Differential Lock Collar until it was completely worn away. It apparently was made of much softer metal than the collar because the collar showed no wear at all.

After making these repairs and reinstalling the Hydrostatic Transmission /Differential into the GT3200 Tractor I expected it to work without purging just like the 3240 did. Not so.

I went through all of the procedures elaborated above to purge the air out of the system but I could not get this Transmission /Differential to work even though it was working well, except for the differential Lock problem, before the tear-down.

I don’t know what to do next short of letting my local Cub Cadet dealer take a crack at it. Any advice would be appreciated.

Thanks,
Veegee2

[Oak]

Veegee, welcome to OCC. I'm not sure what to tell you but I'm thinking you probably know more on the transmission than the dealer does by now.

Does the steering and lift work?
Have you done the transmission pressure test as per the manual?

[veegee2]

The steering and lift do not work so there is zero pressure in the system and therefore there is nothing to test for.

I also talked to the head service technician at my local Cub Cadet dealership and relayed to him the complete story of my problem (See above) of not being able to purge the air from my hydro-static system after a disassembly/reassembly of the rear Axle/Differential. He just shook his head and said that he had no clue for what I should do next.

[FrankF3]

Does the 3000 series tractor have a hydro filter setup like all the other cub cadet hydros do - inline in the oil path from the sump? Could the filter be leaking air and not allowing the hydro to prime?

[Sam Mac]

I'll toss out a couple things,
1: Possible plugged suction line to the charge pump.
2: Charge pump installed backwards
3: Wrong or bad filter.

Did the trans you bought come with the pump, or are you using your pump?

[Oak]

There is also an auxiliary filter inside the pump. Have you checked that? It is part # HG-2510090
http://assets.partstree.com/web4/pho...e4c0e/full.png

I have never had to purge any air from a 3k machine yet. Does the service manual tell you to do that?

I'm with the others, if you don't have steering or lift it sounds like something pump related.

[veegee2]

A bell went off in my head when I read the post from Sam Mac. One of the things he mentioned was, “3: Wrong or bad filter.”

When I was reassembling the GT3200 Differential the only filter I had on hand was an STP S16. It was listed as an equivalent filter for the Cub Cadet 923-3014 hydraulic filter on http://www.oilfilter-crossreference....CADET/923-3014 so I used it.

Since I was having no luck getting my hydraulic system purged using the standard procedure I bought a Cub Cadet 923-3014 hydraulic filter and installed it in place of the STP S16 filter. I wasn’t really expecting any change by this filter swap. I then started the tractor and without engaging the bypass valve I first pressed the forward pedal and then the reverse pedal. After about the fourth cycle the rear wheels started turning and I said, “Thank you Lord”. The power steering and the lift cylinder also began working.

I was pleasantly surprised but it left me wondering what the difference was between these two filters.

After topping off the fluid level to the fill mark I then took the GT3200 for a test drive. The tractor had now developed a bucking mode when the forward pedal was pressed. This bucking only occurs when the tractor is accelerating and quits when the cruising speed is reached. The movement was smooth in reverse. I thought this might just be temporary but after I mowed my whole back yard, going backward and forward it hasn’t gotten any better. The tractor did not behave this way before the differential repair.

I thought the problem might be the Damper Cylinder but it is the original one used when the tractor was operating normally. Just to make sure I compared the operation of this Damper to two others that I had on hand by just extending and retracting the plunger by hand and they all worked exactly the same way.

Does anyone know what might be causing this bucking mode when the forward pedal is engaged?

Thanks for all the suggestions for my original problem.

[veegee2]

I was not aware that there was an auxiliary filter inside the pump. Is this filter cleanable or does it need to be replaced?

I was wondering what that Hex protrusion on the pump was for so I’m assuming it is used to screw off the cap to gain access to this auxiliary filter.

[Oak]

I've never had to change one yet but they do sell them so I guess they are replaceable.

There was a guy on here a year or 2 ago with a similar issue like you have. The dealer found that his front mounting bolts were not tight on the transmission and it was causing the issue. Probably not your problem but just throwing that out there.

Does it sound like you are having pump cavitation when it is surging?

I run Rotella 15w40 oil and Wix 51410 filters in my hydro transmissions. For what it cost, I would drain what you have in there, save it and install a new Wix filter and Rotella just to rule that out.

[veegee2]

I have been running my GT3200 to cut grass but it still has the bucking problem going forward.

I decided to check the charge pump filter today. It is actually a very fine screen filter that is easily cleaned with compressed air. It was a little dirty but not clogged. I also changed out the Hydraulic Damper Cylinder while I had it torn down.

Needless to say I was very disappointed when these procedures did not affect the bucking problem.

Oak, you asked, “Does it sound like you are having pump cavitation when it is surging?” I do not know what pump cavitation sounds like but I do not hear any different sounds than I do with my 3240 tractor which does not have this problem.

What would be the cause of pump cavitation?

You also mentioned that you use Rotella 15W40 oil but you did not specify the T number. When I looked it up at Wal-Mart they show several T numbers. I am ready to try the Rotella oil so could you please list the T number also.

Thanks,