Update: FIXED Loader raising slow all of a sudden

[GunnerBob]

I have a B3300SU HST with LA504 loader. While using today, it all of a sudden started raising extremely slow.

- 3-point works fine
- bucket curls fine
- FEL lowers fine

After some searching here, I tried moving the FEL and 3-pt up at the same time. Neither moved until I released the FEL control. 3-pt went up fine immediately. I then connected the White hose to the Blue connector, and the Yellow hose to the Red connector. Boom moved up at normal speed, but only up. Wouldn‘t go down. I then connected the blue hose to the white connector & red hose to yellow connector. Bucket curled extremely slowly. It seems I moved the problem, so I don’t think it’s in the loader.

Could it be a relief valve stuck? I saw that as a possibility when I was looking. Unfortunately, I can’t seem to find a WSM for my tractor.

I have some mechanical aptitude, but not a lot of experience with hydraulics. Any help/advice would be appreciated.

Bob
Update (TLDR): Replacing the female couplers (white & yellow) on the loader side fixed the problem. See below for details.

 

[dlsmith]

Did you check the linkage for any problems?

 

[Henro]

I have a B3300SU HST with LA504 loader. While using today, it all of a sudden started raising extremely slow.

- 3-point works fine
- bucket curls fine
- FEL lowers fine

After some searching here, I tried moving the FEL and 3-pt up at the same time. Neither moved until I released the FEL control. 3-pt went up fine immediately. I then connected the White hose to the Blue connector, and the Yellow hose to the Red connector. Boom moved up at normal speed, but only up. Wouldn‘t go down. I then connected the blue hose to the white connector & red hose to yellow connector. Bucket curled extremely slowly. It seems I moved the problem, so I don’t think it’s in the loader.

Could it be a relief valve stuck? I saw that as a possibility when I was looking. Unfortunately, I can’t seem to find a WSM for my tractor.

I have some mechanical aptitude, but not a lot of experience with hydraulics. Any help/advice would be appreciated.

Bob

Generally, if you want to swap hoses for a test, you need to swap them in pairs...if you only swapped two hoses...not a valid test, as far as I can see, but I do not know your tractor.

 

[GunnerBob]

Generally, if you want to swap hoses for a test, you need to swap them in pairs...if you only swapped two hoses...not a valid test, as far as I can see, but I do not know your tractor.

I eventually had them swapped in pairs. .

 

[GunnerBob]

Did you check the linkage for any problems?

I just looked and the control arm seems to be moving the valve correctly in all directions.

 

[whitetiger]

I eventually had them swapped in pairs. .

You most likely have a failed quick coupler.

 

[GunnerBob]

I eventually had them swapped in pairs. .

I may have misunderstood what you meant. I just went back out and just swapped the 2 lines for up/down. (White and Yellow lines). The loader raised fine, and lowered ok, but a lot slower than it went up.

When I put them back on correctly, the loader raised correctly one time, and then went back to the issue I’ve been having.

thanks for the input!
bob

 

[GunnerBob]

You most likely have a failed quick coupler.

Is there any way to troubleshoot that? I looked on the parts diagram & could not find “quick coupler”. Does it have a different name?

thanks
bob

 

[whitetiger]

Is there any way to troubleshoot that? I looked on the parts diagram & could not find “quick coupler”. Does it have a different name?

thanks
bob

The quick couples are on the ends of the loader hoses, you use them the connect the hose to the loader control valve.

 

[RCW]

Is there any way to troubleshoot that? I looked on the parts diagram & could not find “quick coupler”. Does it have a different name?

thanks
bob

First, I think you did trouble shoot it already. You swapped the lift pair (Wh/Y) with the curl pair (R/Bl) and moved the problem.

Second, whitetiger has forgotten more about Kubota tractors than I’ll ever know. Smart guy with a lot of experience turning wrenches on these.

The quick couplers are the hydraulic fittings you use to connect/disconnect the loader. Male and female halves.

On my loader, the female half is on the loader. Male on the tractor.

Betting it’s a female coupler on that circuit. I’d change both of them. Wouldn’t do the other pair, unless you deem it prudent.

PS - I see TheOldHokie also replied. He’s a real hydraulic expert here. Very smart fellow also.

 

[TheOldHokie]

I may have misunderstood what you meant. I just went back out and just swapped the 2 lines for up/down. (White and Yellow lines). The loader raised fine, and lowered ok, but a lot slower than it went up.

When I put them back on correctly, the loader raised correctly one time, and then went back to the issue I’ve been having.

thanks for the input!
bob

Swapping lines doesnt tell you much if you dont understand the operation. I dont know the specifics of that valve but here is how most Kuboat loader valves operate:

1. The bucket work port sends pressurized oil to the cylinder to curl and return oil from the cylinder is sent to tank. All down stream functions are blocked.
2. The other bucket work port sends pressurized oil to the cylinder to extend and return oil from the cylinder is looped back to the extend end to speed up dump. All down stream functions are blocked.
3. The lift work ports send pressurized oil to the cylinder and return oil is sent to the power beyond port where it is available to power down stream functions.

Based on that and your description something is blocking the downstream flow of oil from the UP side of the loader valve/cylinder. The loader cant lift because oil flow is blocked and the the 3pt will not operate for the same reason. The most likely culprit is the quick connect coupler on the UP loader valve port.

Dan

 

[jimh406]

I would check the hydraulic fluid level, grease the FEL, and if you haven't changed the hydraulic filters in a while do that and/or change out the hydraulic fluid if it is due or past due.

I'd also look at the hydraulic cylinders/rams to make sure you haven't bent them.

 

[GunnerBob]

The quick couples are on the ends of the loader hoses, you use them the connect the hose to the loader control valve.

Thank you

 

[GunnerBob]

Swapping lines doesnt tell you much if you dont understand the operation. I dont know the specifics of that valve but here is how most Kuboat loader valves operate:

1. The bucket work port sends pressurized oil to the cylinder to curl and return oil from the cylinder is sent to tank. All down stream functions are blocked.
2. The other bucket work port sends pressurized oil to the cylinder to extend and return oil from the cylinder is looped back to the extend end to speed up dump. All down stream functions are blocked.
3. The lift work ports send pressurized oil to the cylinder and return oil is sent to the power beyond port where it is available to power down stream functions.

Based on that and your description something is blocking the downstream flow of oil from the UP side of the loader valve/cylinder. The loader cant lift because oil flow is blocked and the the 3pt will not operate for the same reason. The most likely culprit is the quick connect coupler on the UP loader valve port.

Dan

That makes sense to me. Thanks.

 

[GunnerBob]

First, I think you did trouble shoot it already. You swapped the lift pair (Wh/Y) with the curl pair (R/Bl) and moved the problem.

Second, whitetiger has forgotten more about Kubota tractors than I’ll ever know. Smart guy with a lot of experience turning wrenches on these.

The quick couplers are the hydraulic fittings you use to connect/disconnect the loader. Male and female halves.

On my loader, the female half is on the loader. Male on the tractor.

Betting it’s a female coupler on that circuit. I’d change both of them. Wouldn’t do the other pair, unless you deem it prudent.

PS - I see TheOldHokie also replied. He’s a real hydraulic expert here. Very smart fellow also.

Thanks for clarifying.

 

[GunnerBob]

First, thanks to Henro, whitetiger, RCW, TheOldHokie, & jimh406 for all of the quick replies, especially on a holiday.

Also, I am so grateful for this forum and the many resources you all have compiled. I was able to find the part number I needed pretty quickly, and gave it to my Kubota dealer. They had them in stock, and my tractor is back working!

I ended up replacing the female quick couplers on the white & yellow hoses, as recommended by whitetiger, RCW, & TheOldHokie. That did the trick.

Thanks again…without your advice my tractor would be awaiting an expensive trip to the shop, I think.

Gratefully,
Bob