Repaired hydro pump on 743 now have no movement, no hydraulics.

[NYDiggerman]

Had to replace front input shaft on my 743 after U joint disintegrated. Also replaced vane cartridge on my hydraulic pump while I had it apart. Now I have it back together and I have no movement of drive or hydraulics. If something was wrong in transmission it should still pump from the front half. I loosened the out put line on the hydraulic pump (not running) and had oil. I had to push it into the garage without it running. It was hard going but I just overpowered the motors. Is there a valve that could be stuck?

 

[Tazza]

Do you still have lift and tilt? i wonder if the cartridge could have been put in 180 degrees out?

 

[Tazza]

Do you still have lift and tilt? i wonder if the cartridge could have been put in 180 degrees out?

One other thing, if you bump the starter with the front off the hydraulic pump, does the shaft spin? Juat making sure the shaft is still intact inside the pump, but i'm sure you checked all that out when you replaced the broken end at the ujoint

 

[HanSolo]

I would double check the the drive coupler attached to the new u-joint. Surely you got it lined up and seated when you put the engine back in. There's also a key-way on the input shaft of the hydrostatic pump that fixes the position of the male splined shaft. I wonder if that key-way got sheared or slid out during re-assembly? I had to do some "corrective surgery" on mine to get that joker to fit just right.

 

[NYDiggerman]

I would double check the the drive coupler attached to the new u-joint. Surely you got it lined up and seated when you put the engine back in. There's also a key-way on the input shaft of the hydrostatic pump that fixes the position of the male splined shaft. I wonder if that key-way got sheared or slid out during re-assembly? I had to do some "corrective surgery" on mine to get that joker to fit just right.

I have no lift tilt or other functions. I do know the U joint is hooked. When I contorted myself to hook it up it slid on and I could feel it turning the adapter spline. Foolish me I did not spin the input shaft before buttoning everything up. Am I right in thinking I will have to drop the hydraulic reservoir again to pull the end off the pump? I appreciate the good input.

 

[Tazza]

I have no lift tilt or other functions. I do know the U joint is hooked. When I contorted myself to hook it up it slid on and I could feel it turning the adapter spline. Foolish me I did not spin the input shaft before buttoning everything up. Am I right in thinking I will have to drop the hydraulic reservoir again to pull the end off the pump? I appreciate the good input.

Yeah, you will need to dump the oil out....
There is a coupler that joins the shaft inside between the two pump sections, could that have been broken or left out? For you to get no hydraulics, it seems there is something not connected.

 

[NYDiggerman]

Yeah, you will need to dump the oil out....
There is a coupler that joins the shaft inside between the two pump sections, could that have been broken or left out? For you to get no hydraulics, it seems there is something not connected.

I thought about this coupler. I know I pulled it out when I had the tranny apart but I'm sure I put it in since it's not hanging around in my spare parts. I hate to think about pulling it apart to see. I'm going to pull the end from the hydraulic pump first to see if it rotates. One of the replies mentioned something about the cartridge being installed in the wrong orientation. Is this a possibility? Is there a way to know the right orientation? thanks

 

[Tazza]

I thought about this coupler. I know I pulled it out when I had the tranny apart but I'm sure I put it in since it's not hanging around in my spare parts. I hate to think about pulling it apart to see. I'm going to pull the end from the hydraulic pump first to see if it rotates. One of the replies mentioned something about the cartridge being installed in the wrong orientation. Is this a possibility? Is there a way to know the right orientation? thanks

I'd start with the hydraulic pump too. The motor should rotate clockwise from looking from the engine bay i believe. Ensure the arrow cast into the cartridge is pointing in the same direction.

 

[NYDiggerman]

I'd start with the hydraulic pump too. The motor should rotate clockwise from looking from the engine bay i believe. Ensure the arrow cast into the cartridge is pointing in the same direction.

OK. I dumped the oil (I should have stock in speedie dry). Pulled end off pump and shaft is turning, all splines connected, You were right Taz, I had cartridge in backwards. I didn't realize those marks were arrows. Arrows on opposite sides of cartridge. Cartridge looks symmetrical so assembled with one side with arrow on top of pump.(arrow pointing correct way) Filled with oil in hopefull anticipation, Started, no difference. No hydraulics, no wheel motion. I still think it is in pump? Maybe arrow should be on side of pump?

 

[Tazza]

OK. I dumped the oil (I should have stock in speedie dry). Pulled end off pump and shaft is turning, all splines connected, You were right Taz, I had cartridge in backwards. I didn't realize those marks were arrows. Arrows on opposite sides of cartridge. Cartridge looks symmetrical so assembled with one side with arrow on top of pump.(arrow pointing correct way) Filled with oil in hopefull anticipation, Started, no difference. No hydraulics, no wheel motion. I still think it is in pump? Maybe arrow should be on side of pump?

From memory, the arrows are top and bottom, so that shouldn'e be an issue.
What happens if you remove the line from the hydraulic pump, is there any oil dribbling out? what about when you start the machine? i just want to make sure that the pump is primed. I assume it was full of oil when you removed the cartridge to flip it over?
If there is oil there, i don't know why it's not generating pressure.
When i replaced my pump, it was all empty. I put a jack under the rear to stop it tipping back and used a chain block on the arms to lift them up while someone sat in the cab with their heel on the lift pedal. This will draw oil through the hydraulic pumps and into the cylinders. This way you know the system has some oil and it should pick up from there.

 

[NYDiggerman]

From memory, the arrows are top and bottom, so that shouldn'e be an issue.
What happens if you remove the line from the hydraulic pump, is there any oil dribbling out? what about when you start the machine? i just want to make sure that the pump is primed. I assume it was full of oil when you removed the cartridge to flip it over?
If there is oil there, i don't know why it's not generating pressure.
When i replaced my pump, it was all empty. I put a jack under the rear to stop it tipping back and used a chain block on the arms to lift them up while someone sat in the cab with their heel on the lift pedal. This will draw oil through the hydraulic pumps and into the cylinders. This way you know the system has some oil and it should pick up from there.

I finally found the right orientation for the cartridge and everything is working great. Actually the arrows need to be on the side of the pump. I put the pump together , filled the pump with oil and then connected all the hoses and filled reservoir with oil. After starting I had to bring it to half throttle the first time, for it to pick up pressure. It's working great now. Thanks Taz, it's good to have some one to bounce ideas off.

 

[Tazza]

I finally found the right orientation for the cartridge and everything is working great. Actually the arrows need to be on the side of the pump. I put the pump together , filled the pump with oil and then connected all the hoses and filled reservoir with oil. After starting I had to bring it to half throttle the first time, for it to pick up pressure. It's working great now. Thanks Taz, it's good to have some one to bounce ideas off.

Awesome, glad you got it working again. Something so simple, yet frustrating till you find it.

 

[craigb93]

Awesome, glad you got it working again. Something so simple, yet frustrating till you find it.

The best way to insure that any gear pump primes readily and takes off is to build it and pack it full of STP, that thick motor honey, to ensure that nothing is dry and that the lube won't drain away over the time it takes to complete the job. 100% success over the 40 years the stuff has been on the market. Wrist pins, oil pumps, piston skirts, you name it. Anywhere that scuffing can occur from a dry start-up. -Dick