753 right side forward drive problem

[aftermath]

will go in reverse both drives no probem straight and fast. right side does not want to go forward well or sometimes not at all, left steer forward is fine, so just right side drive forward is not working right. change filters and had fluids flushed, same problem all bucket commands works well Any help is greatly appreciated. Thanks in advance, Chris

 

[OldMachinist]

You can swap sides with the drive motors and see if the problem follows the motor. If it doesn't follow the motor then the problem is in the right side pump.

 

[aftermath]

You can swap sides with the drive motors and see if the problem follows the motor. If it doesn't follow the motor then the problem is in the right side pump.

would it be the pump if it works strong in reverse? Bobcat service tech just told me that that it may be a high pressure valve on the hydrostat. On a hill, it don't seem to hold pressure and wants to limp back. When the fluid was changed, there was what looked like saw dust mixed with the fluid. Thanks for the input. Chris

 

[mllud]

would it be the pump if it works strong in reverse? Bobcat service tech just told me that that it may be a high pressure valve on the hydrostat. On a hill, it don't seem to hold pressure and wants to limp back. When the fluid was changed, there was what looked like saw dust mixed with the fluid. Thanks for the input. Chris

Tazza always talks of a bronze filter in a block where the on the pump. Where hydraulic hoses attach.I dont know if this applies to this model. Mike

 

[skidsteer.ca]

Tazza always talks of a bronze filter in a block where the on the pump. Where hydraulic hoses attach.I dont know if this applies to this model. Mike

Don't thinks its in the hyd motor if it drives fine in one direction. I'm thinking a relief on the motor.
Ken

 

[thetool]

Your service tech is probably correct.
There are four cartridge valves on your hydrostatic pump that act as relief for right and left, forward and reverse, one valve for each.
The problem is, they are on the bottom of the pump and inaccessable unless you pull the pump, if memory serves.
Before you do that, pull the motor hoses at the pump and cap the pump fittings with steel caps. Start the machine and see if it wants to stall when you stroke right forward. If it does not stall, it is probably that valve. If the pump wants to stall, then the problem is in the motor. This is a good test because you eliminate the motor from the circuit, and if your pump builds pressure to stall in one direction, it indicates the really pricey part of the pump is okay. Just don't go wild stalling it out because it's hard on the pump. Just enough to check it.
In the event your pump stalls in all four sides and directions:
The motor has a shuttle that directs low pressure oil(return side, depending on direction of travel)to case drain. A stuck shuttle will give you the same drive problem. You can check that by directing the case drain flow out of the motor into a bucket. Oil will flow when the engine is running, and flow more when you go right reverse. If there is a LOT more flow in right forward, this indicates a stuck shuttle in the motor. That is the oil that should be driving the machine instead of running out of the case drain, or the smallest fitting on the motor.
You really don't want to pull your pump before you eliminate the possibiltiy of a motor problem, AND it's always possible you have a problem with both.
Good Luck

 

[aftermath]

Your service tech is probably correct.
There are four cartridge valves on your hydrostatic pump that act as relief for right and left, forward and reverse, one valve for each.
The problem is, they are on the bottom of the pump and inaccessable unless you pull the pump, if memory serves.
Before you do that, pull the motor hoses at the pump and cap the pump fittings with steel caps. Start the machine and see if it wants to stall when you stroke right forward. If it does not stall, it is probably that valve. If the pump wants to stall, then the problem is in the motor. This is a good test because you eliminate the motor from the circuit, and if your pump builds pressure to stall in one direction, it indicates the really pricey part of the pump is okay. Just don't go wild stalling it out because it's hard on the pump. Just enough to check it.
In the event your pump stalls in all four sides and directions:
The motor has a shuttle that directs low pressure oil(return side, depending on direction of travel)to case drain. A stuck shuttle will give you the same drive problem. You can check that by directing the case drain flow out of the motor into a bucket. Oil will flow when the engine is running, and flow more when you go right reverse. If there is a LOT more flow in right forward, this indicates a stuck shuttle in the motor. That is the oil that should be driving the machine instead of running out of the case drain, or the smallest fitting on the motor.
You really don't want to pull your pump before you eliminate the possibiltiy of a motor problem, AND it's always possible you have a problem with both.
Good Luck

ok just picked this machine up from the Bobcat shade tree that changed the fluid at the local rental shop where I do business periodically. Said he did not change the filter but charged me 2 bills and seems worse than before. NOW it is still weak right side forward, and does not want to turn left (left steer back right forward and nothing but bogging just left steer back or just right steer forward but will catch onboth sides periodically) but will still consistantly go in reverse both sides like moody's goose, very strong. I know how things can be with mechanical issues. I'm trying not to get raped by the Bobcat dealer for servce over something simple if in fact that is what it is. All help is appreciated, TIA Chris

 

[Tazza]

ok just picked this machine up from the Bobcat shade tree that changed the fluid at the local rental shop where I do business periodically. Said he did not change the filter but charged me 2 bills and seems worse than before. NOW it is still weak right side forward, and does not want to turn left (left steer back right forward and nothing but bogging just left steer back or just right steer forward but will catch onboth sides periodically) but will still consistantly go in reverse both sides like moody's goose, very strong. I know how things can be with mechanical issues. I'm trying not to get raped by the Bobcat dealer for servce over something simple if in fact that is what it is. All help is appreciated, TIA Chris

There are indeed relief valves for forward and reverse on both sides, as it has been mentioned earlier there are 2 on the bottom, and 2 on the top. For you to have that much power loss i would doubt the shuttle valve is stuck though. If you swap hoses at the pump, top to bottom bottom to top and see if you get good forward power and no reverse it would rule out any thoughts of the shuttle being stuck.
There isn't a bronze port block on thee machines.
You mentioned like wood shavings in the filter, can you give a little more detail? that doesn't sound at all good to me.

 

[aftermath]

There are indeed relief valves for forward and reverse on both sides, as it has been mentioned earlier there are 2 on the bottom, and 2 on the top. For you to have that much power loss i would doubt the shuttle valve is stuck though. If you swap hoses at the pump, top to bottom bottom to top and see if you get good forward power and no reverse it would rule out any thoughts of the shuttle being stuck.
There isn't a bronze port block on thee machines.
You mentioned like wood shavings in the filter, can you give a little more detail? that doesn't sound at all good to me.

You guys are great and this forum freakin rox! I have an update. I took my machine to the dealer and they returned with the following quote. My question is: is this something easily to do? I have a collection of hot rods and have worked on my own stuff since I was 13.....39 now !!! what are the ins and outs?....I'm going to order a service manual on Ebay today. Thanks guys !!!! Estimate from Bobcat: This estimate is to repair spool in control valve, reseal right side drive motor, and reset steering back to proper specs.This estimate does not include any additional parts or labor that maybe needed during the repair.This estimate does not include any taxes nor freight charges. 1 6659601 seal kit $96.81 $96.81 1 6589226 bonnet $8.95 $8.95 2 6592094 screws $4.17 $8.34 1 6531270 sleeve $39.40 $39.40 1 6592098 washer $1.53 $1.53 1 799119 ring $1.86 $1.86 2 6592105 balls $1.09 $2.18 1 6592107 spring $2.83 $2.83 1 6983247 brake $5.84 $5.84 SubTotal $167.74 Labor $962.50 EPA/Shop Supp $20.00 TOTAL $1,150.24

 

[Tazza]

You guys are great and this forum freakin rox! I have an update. I took my machine to the dealer and they returned with the following quote. My question is: is this something easily to do? I have a collection of hot rods and have worked on my own stuff since I was 13.....39 now !!! what are the ins and outs?....I'm going to order a service manual on Ebay today. Thanks guys !!!! Estimate from Bobcat: This estimate is to repair spool in control valve, reseal right side drive motor, and reset steering back to proper specs.This estimate does not include any additional parts or labor that maybe needed during the repair.This estimate does not include any taxes nor freight charges. 1 6659601 seal kit $96.81 $96.81 1 6589226 bonnet $8.95 $8.95 2 6592094 screws $4.17 $8.34 1 6531270 sleeve $39.40 $39.40 1 6592098 washer $1.53 $1.53 1 799119 ring $1.86 $1.86 2 6592105 balls $1.09 $2.18 1 6592107 spring $2.83 $2.83 1 6983247 brake $5.84 $5.84 SubTotal $167.74 Labor $962.50 EPA/Shop Supp $20.00 TOTAL $1,150.24

From that they believe the problem is your drive motor?
Your control block is also leaking?
Pulling the motor isn't that hard, it is fiddly but can be done. I was lucky and the seals were shredded but the backup rings were in good shape. $11 worth of seals either side fixed my problems.
If it drives in one direction properly it really doesn't seem like a motor, if you look inside a motor you would understand. The mack section has your 2 high pressure inlets, these are separated by O tings and backup rings. If you blow a seal the high pressure will flow back to the low pressure side without doing any work. No matter if it is forward or reverse it will do the same.
I would swap the hoses at the pump, top to bottom, bottom to top on the problem side see if the problem reverses its self. If it does, you have confirmed its in the pump, most probably the relief valve.

 

[aftermath]

From that they believe the problem is your drive motor?
Your control block is also leaking?
Pulling the motor isn't that hard, it is fiddly but can be done. I was lucky and the seals were shredded but the backup rings were in good shape. $11 worth of seals either side fixed my problems.
If it drives in one direction properly it really doesn't seem like a motor, if you look inside a motor you would understand. The mack section has your 2 high pressure inlets, these are separated by O tings and backup rings. If you blow a seal the high pressure will flow back to the low pressure side without doing any work. No matter if it is forward or reverse it will do the same.
I would swap the hoses at the pump, top to bottom, bottom to top on the problem side see if the problem reverses its self. If it does, you have confirmed its in the pump, most probably the relief valve.

Ok, the bobcat tech agreed to do the work imn the quote for $663.00 half of the quote. He told me that the left side problems was a result of right side blow-by. He told me that after he finished the work, "it will drive like a new one" well they called me Thursday and said right drive is working fine now but the left side drive motor needs seals also and they want more money now. I told them no and that they are the pro's and a deal is a deal. Anybody know where I can buy the seals for the left side drive motor if I eed to get them? TIA Chris

 

[Tazza]

Ok, the bobcat tech agreed to do the work imn the quote for $663.00 half of the quote. He told me that the left side problems was a result of right side blow-by. He told me that after he finished the work, "it will drive like a new one" well they called me Thursday and said right drive is working fine now but the left side drive motor needs seals also and they want more money now. I told them no and that they are the pro's and a deal is a deal. Anybody know where I can buy the seals for the left side drive motor if I eed to get them? TIA Chris

Your dealer has seal kits, they are around $70-100. If your backup rings aren't broken you can just replace the O rings, my 753 needed $11 worth or O rings to replace the whole lot. $22 for both sides, you can't beat that. But when you open the motor you will see 3 backup rings made of plastic, the book said not to re-use them but i did and they work 100%.

 

[sterlclan]

Your dealer has seal kits, they are around $70-100. If your backup rings aren't broken you can just replace the O rings, my 753 needed $11 worth or O rings to replace the whole lot. $22 for both sides, you can't beat that. But when you open the motor you will see 3 backup rings made of plastic, the book said not to re-use them but i did and they work 100%.

http://www.skidloaderpumps.com/servlet/StoreFront ...... pumps parts and such......good luck

 

[Dael]

I have the exact same problem on my 753!! Please let me know what the problem was and how you fixed it. I've been using it like this for about 1.5 years and it felt like it gave in this arvo, just a slight shudder then nothing when trying to go forward on the right side.

 

[Dael]

Ok, the bobcat tech agreed to do the work imn the quote for $663.00 half of the quote. He told me that the left side problems was a result of right side blow-by. He told me that after he finished the work, "it will drive like a new one" well they called me Thursday and said right drive is working fine now but the left side drive motor needs seals also and they want more money now. I told them no and that they are the pro's and a deal is a deal. Anybody know where I can buy the seals for the left side drive motor if I eed to get them? TIA Chris

Please let me know how it goes, I have the exact same problem!!

 

[Stumper1624]

Couple years ago I paid mega bucks to get the seal kit for my drive motors and when i pulled the motor apart I found one of the housings had a micro crak in it that was leaking the pressure off. Seals couldn't fix it and I ended up buying a 2300 dollar upgraded replacement motor. Seals and pump parts are next to impossible to get for these motors. so, plan on buying a new motor. Not cheap to get no matter where you search for one.

 

[Dael]

Couple years ago I paid mega bucks to get the seal kit for my drive motors and when i pulled the motor apart I found one of the housings had a micro crak in it that was leaking the pressure off. Seals couldn't fix it and I ended up buying a 2300 dollar upgraded replacement motor. Seals and pump parts are next to impossible to get for these motors. so, plan on buying a new motor. Not cheap to get no matter where you search for one.

Oh shit. I only paid $5000 for the bobcat. But then it's almost unusable without the new drive motor so it looks like that's what I have to do.

 

[Stumper1624]

Oh shit. I only paid $5000 for the bobcat. But then it's almost unusable without the new drive motor so it looks like that's what I have to do.

Go to Bob Cats site and look up the pump by serial number and it will show the part numbers with all the supersessions. I can't remember what my motor number was off hand. but, that particular motor is one with no parts availability.
I got my Motor from New Holland Rochester Jesse Staeter in parts is fantastic to work with.

 

[Dael]

OK. I'll check it out. Thanks very much for the tip.

 

[Dael]

Couple years ago I paid mega bucks to get the seal kit for my drive motors and when i pulled the motor apart I found one of the housings had a micro crak in it that was leaking the pressure off. Seals couldn't fix it and I ended up buying a 2300 dollar upgraded replacement motor. Seals and pump parts are next to impossible to get for these motors. so, plan on buying a new motor. Not cheap to get no matter where you search for ones