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Hello everyone.

I'm getting a couple project mowers next week. A 721d and a 928d. They were both purchased new in 1997 and were used on a tree farm up until last summer. They have been sitting out in the field for at least a year, and from appearances, I'm guessing they have never been parked under a roof. The 928d is missing the dipstick for the hydro fluid tank and the oil is slightly milky. I want to get them to my shop prior to doing any work on them. I read something about some dump valves at the hydro motors that need to be opened prior to moving them. I would appreciate anyone that could offer a little more detail and helpful advise that may save me some head aches. The deal we made is that if I can get one running, I can keep one for myself. I'm excited about this project.

Thanks for any help you can offer!
Tim

The dump valves are located on the pumps. Being its a 1997 , you probably have (2) G1 transmissions. Therefore you will have (2) dump valves ( one on each). I had a 1997 725 , and I beleive that the dump valve nut had a rod running through it to make it easier to turn. I think its one full turn to the left and the mower will free wheel.

bobbysr is right about the rod running through the hole.just rotate counterclockwise to freewheel...russ

Thanks guys!

I took a closer look today and should have taken more pics. There were some rods on top of the pumps that were bent into a triangle shape at the end. They were approximately 3" long. I didn't try to turn them. I hope these are what you are describing as they are easy to get at. If what you are describing is underneath, I have a problem with snakes, spiders, wasps, and anything else that may be hiding under the tall grass. If they are under the machine, I'm gonna pull them out onto fresh cut ground and hope I don't damage anything.

I got more details today.

The 721D has 1135 hours on the meter, the deck is a Model 9561S, and it has a deck lift toggle switch on the control panel. The engine cover was unbolted (but not removed) and the hose from the air cleaner to the intake was removed. I didn't see any sign of water in the intake. The fuel lines were disconnected at the injectors and the connections are rusted though not so bad a little fine sanding cloth can't clean it up. The radiator looked to be empty and rusty inside. the hydraulic fluid was at an acceptable level on the dipstick and looked normal. The engine oil level was a solid 3/4" above the full mark and as black as any normal diesel engine oil.

The 928D has 650 hours on the meter, the deck is a model 9372S, and no deck lift. This tractor has not been taken apart, the radiator is full of green coolant, the engine oil is also over full, and the dipstick is missing on the hydro fluid tank and the fluid is starting to get milky.

There is also a grass catcher that I haven't seen yet. I have a couple pics on my cell phone. I'll try to get them posted shortly.

I'll keep y'all posted on my progress and Thanks again for any suggestions.

I've got a couple pics.

One is of the tractors and the other is of the dump valve I think. Now if I can get them posted.

Tim,the last pic is the dump valve.just rotate it and you should be good to go...russ

Thanks Russ.

I'll get more pics and update as I go with this project.

Can anyone tell me if there is a drain plug for the hydraulic fluid tank? I really want the milky fluid drained and tank flushed prior to going much further. If there is no drain plug, what is the recommended procedure for changing fluid?

Thanks
Tim.

There might be a plug on the tank reservoir . Otherwise, pull off the lowest hose & let drain that way. Don't forget new hydro filters.

Thanks Bobby

I'm gonna try to get them home tomorrow provided no emergencies come up.
Tim

Tim,I changed mine 3 yrs ago but can't remember if there is a drain plug.don't see one in the manual. I'll look at mine tomorrow and let you know...russ

I got them both home Wednesday and under a shed. There is a drain plug on the Hydraulic tank. The owner told me she wanted the 721d so that means I'm getting the 928d. I started on the 721d last night. I replaced all the rubber fuel lines and fuel filter, cleaned the fuel tank and filled with fresh diesel. I replaced a couple relays that were missing. I pulled them from the 928d and went to the auto parts store for new ones. With fresh battery in place, I hit the ignition switch and nothing. Although the glow plug system works. I jumped the starter solenoid and it spins, but is not engaging. I'll be taking it off and to the starter rebuild shop Monday.

What is the least expensive compatible hydro fluid for these machines?

Thanks
Tim

The pic is of them at my shop.

With G2 transmissions, Mobile DTE-26 is useable. Not sure about G1 transmissions. Might want to search lawnsite.com

I got to work on the 721D yesterday. Its a wiring nightmare. Melted wires, lots of electrical tape, etc... I did get the control panel to light up and the engine to turn using the ignition switch. The fuel solenoid is fried (shouldn't be a problem to bypass) and the autozone relays are fried also. If anyone knows an aftermarket part number for the correct relays that info would be very helpful. The fuel delivery system is not working properly. Its not picking up fuel from the tank. The diaphram in the pump looks ok, and when I gravity feed the system it pumps through the bypass and not the injectors.

Any knowledge or experience with the fuel system would be helpful.
Thanks
Tim

Its been a while since I've posted on this project, but I haven't had lots of time for it until the last couple weeks. I've only worked with the 721d. I had to get a fuel injector pump from ebay, the old one was unrepairable according to my local injector shop. It ran good for a bit until I added water to the radiator and it immediatly filled the crank case with water due to a freeze plug behind the timing gears that popped out during the last freeze. That is a rare thing here in MS, but we had three or four days of low teen temps a couple winters back. I pulled the head and all looked good other than minor scars on the cylinder walls. Then pulled the timing cover and found the problem.

After getting it all back together a few days ago, it ran great!! The hydro motors operated and it cut nearly an acre of 1 foot tall grass. The right side seemed a little weak.
At this point, I'm feeling good about this thing, then I feel a hard thump on the right side during a hard turn and shortly thereafter it starts losing forward motion power. It dumped most of the fluid from the hard turn and thump.

There is a pea sized hole in the housing. I'm gonna pull it apart tomorrow to see if it is something I can repair. If not, I'll be needing a right side drive motor. If I can't get this thing running correctly soon, I'm gonna have some parts for sale.

After pullung the right motor and cleaning it up, I found severe pitting in the aluminum housing almost looked like worm holes. All I can figure is some fertilizer got there and stayed for a couple years. I cleaned it all up with a diamond burr tool and filled the holes with epoxy.

After two days of cure time, I put it back in with fresh 15w50 mobile-1 synthetic and it ran great for a couple minutes then the left drive motor stopped all forward motion.

This thing works great if I can learn to cut in reverse or if someone needs a perfect circle cut. The right motor is working great now [no leaks!!]. The left motor is strong in reverse, just no forward motion.

I pulled it under my favorite shade tree without turning the bypass levers [30 ft]. could that have caused this problem?

I called the folks at grasshopper today and they had no easy fix for me. They just said not to go into the drive motor. I felt like the fat kid I used to be being told not to eat the candy. They also said the drive motors are no longer made for this model. He said it was a Gemini made by Eaton. {How cool is that?!!!!}

I'll update y'all when I get more done.

Did you get any more accomplished,... or do you have some parts for sale? :tongue:

I got the engine running and cut 3 or 4 acres a couple times until it developed a hydro fluid leak. I haven't given up yet. I'm taking a break from it and getting some metal on a couple buildings here at home. There are holes in the top of one of the drive motors. JB-Weld didnt hold. I'm planning to disassemble it and have it welded up.

Never had any luck with JB weld.
However I have use radiator repair epoxy ribbon for "temporary" roadside repairs in a lot of motorcycle crankcases when the brake levr punches a hole in the case.
Some of these have held for better than 20 years, just never got around to replacing the covers.

There are other products like "Lumiweld" that are easier to use than direct welding and can be used in situ.
Other than that a gas welder should also be able to add weld to the cases in situ. I am only a so-so welder but manage to do this regularly.

I've just finished reading the whole thread.

I must say I am a little jealous. I love Grasshopper mowers. They are just unique. It's nice they were given to you and you can keep one.

I do hope you get both of them running fine soon. Get some more pictures of your progress!

Thanks for your questions, comments, and advise. I need to get this project back up and going. A friend of mine ordered and used some of those aluminum braising rods and offered to do the repair if I bring the disassembled housing to him. He is confident it will work great in this application. Its gonna be at least 3 more weeks till I can get back on it. I will keep updating this thread as long as there is interest. I'll get some photos of the process also.

I didn't conclude exactly where your hole was on your housing, but are you going to disassemble to the point of removing the drive pump, driven pump, or both to do this welding?

I will assume you've heard not to get any of the balls miss matched from the sleeves that they are currently in.

iirc, there is a .0002 ball to sleeve match!

TimGoodman said:

Thanks for your questions, comments, and advise. I need to get this project back up and going. A friend of mine ordered and used some of those aluminum braising rods and offered to do the repair if I bring the disassembled housing to him. He is confident it will work great in this application. Its gonna be at least 3 more weeks till I can get back on it. I will keep updating this thread as long as there is interest. I'll get some photos of the process also.

Click to expand...

You definetly have my interest! I love these machines.

Thanks Hemi I haven't heard much about taking these things apart other than don't. That info is the stuff I'm gonna need. The holes look like worm holes as if acid or fertilizer ate into the aluminum from the top side of the gear housing. There is one hole completely through about 1/8" that I can see the spider gears through. I'll try to make some time over the next couple days to get it back out and cleaned up. I'll post some pics.

I'm not sure how deep I will have to go into it. Hopefully I don't have to get into the actual pumping stuff. It didn't go to well for me when I went into the injector pump. I did find a good used injector pump on ebay at a good price.

Hello everyone!
I'm throwing in the towel on these mowers. I listed them on eBay last night. The starting bid is $800.00.
If you need some parts, These would be great to have. My user name on eBay is gtim8809. Go check them out.
Thanks for all your input and responses here.

Wish you where a lot closer. The 7-8 hrs between us pretty well kills it for me.

Curious questions:

1) Does the throttle & fuel cut off shafts of the 721D have any signs of leakage?

2) Do you think a 928 motor would bolt into a 721d. Aren't the frames, & sub frames the same?