9BL 963B boom hydraulics weak after a few hours of work.

[CameronEldridge]

Hello guys! I have a 963B that we have been pulling our hair out on for quite some time. If I have this machine out on a job, you work it 3-4 hours, the boom gets extremely weak. For the first couple of hours, the machine operates flawlessly, lots of power and does great! Until it doesn't, the boom hydraulics start getting weaker and weaker, usually starts off slow and then within 30 minutes or so it will barely pick up the (empty) bucket 3-4' off the ground. We have changed the filters, suction hose, repacked cylinders, had charge pump rebuilt (the pump mounted to the gear case on engine). Still no luck. Machine has the 2 stick controls if that makes any difference. Any help would be extremely appreciated!

 

[Nige]

It seems as though you have done a lot of $$$ repairs but you don't mention anything about testing implement system pressures. Have you ever done this.?

Still no luck.

Luck should have nothing to do with diagnosing this problem IMHO.

 

[CameronEldridge]

It seems as though you have done a lot of $$$ repairs but you don't mention anything about testing implement system pressures. Have you ever done this.?

Luck should have nothing to do with diagnosing this problem IMHO.

We have not, and you are exactly right, I have listened to too many people that there brothers uncle had one with the exact problem and (X) fixed it.
To be honest, I do not know how to test those pressures or what they would need to be.
Is there a manual available for this information?

 

[Nige]

I suggest that you also need to do a few more basic checks alongside what you have done so far.

Do you have an Operation & Maintenance Manual.? If you are carrying out your own PMs, etc, you really should have one. Here's a genuine OEM one on CD for $40. https://www.ebay.com/itm/314509894760

What oil type & viscosity are you using.?
Have you ever taken an oil sample and had it analyzed.?

 

[Nige]

Post a full S/N and I will look up the testing procedure for both the pilot system and main system for the implement system.

 

[CameronEldridge]

9BL02127

 

[Nige]

I've sent you some stuff on a message. Feel free to post back here with any questions.

 

[631G]

For what it’s worth our 963B also has the same troubles. We’ve pulled the pump and found that the implement pump was worn and unable to make the correct pressure. Still waiting for it to come back from the shop we sent it out to.

What I’ve been told by the shop so far is that seals over time have degraded/worn and that the housing is worn letting things bypass in stead of making pressure.

We are trying for rebuild at the shops direction that they can get the pump back to working. But if your looking for a replacement pump they’re steep.

I have a thread open on this issue and will be posting back to it as we slowly get things back together on the machine. Maybe this will be of some help.

 

[631G]

Wanted to offer a suggestion for another area to check on your machine with the hydraulic issues. We found that on our 963B that the pilot system was causing it to act up because the pump was cavitating. We had the pilot pump grenade and got to looking into what happened and found that the suction line to the pump had a pin hole in it and that the hose to tank connection had a cracked weld inside the tank. All in all the pump was starving for fluid and finally gave up. it took some digging but we found these issue and got the machine back up.

On the other hand, which you may already be well aware of, parts are getting pretty slim on these older loaders. I could not source a pilot pump from Cat. I was able to get a pump from a breaker yard in Missouri and that got us back up. Don't know the hours on the pump but hopefully it will hang together.

 

[heymccall]

If it's the gear pump, it's available new out of Morton, at $2350, or reman out of York, PA at $1530 plus core.

 

[631G]

If it's the gear pump, it's available new out of Morton, at $2350, or reman out of York, PA at $1530 plus core.

Locally Yancey is our dealer and their parts guys in the pump department were telling me that they had no availability on the pilot pump. The pilot pump shows as part number 107-4321 as a rear section. The pump group with both the charge pump and pilot pump come up as pert number 6E-6046. Says contact dealer... which I've learned means you're S.O.L