Kubota B7800 power steering and 3pt problem

[bmwtomis]

I purchased a couple weeks ago a 2005 B7800 HST. When I purchased it I did a full fluid and filter swap in both the engine and HST. It has about 280hrs on it now. I installed a lawn for my sister and used a 2340lb pto driven soil conditioner. The tractor got a bit hot, not the engine but the tranny. The last half hour of work with it the 3pt would not lift the soil conditioner and the steering was hard. Forward and reverse worked just not as touchy as it was. Could i have done damage to the HST in 4hrs of run time working it somewhat hard? Would it be silly to change filters and Hydraulic fluid again even though i changed them 10hrs ago? I did clean the strainer screen as well.

Thanks,

Tom

 

[newbury]

Welcome aboard.

What are the symptoms after a cool down?
What is the hydraulic level?
What oil did you use?

Per TractorData.com Kubota B7800 tractor information the rear lift is rated at 1,655 lbs so you were doing good to lift it at all.

You might want to repost or get this moved to the hydraulic forum.

 

[bmwtomis]

Symptoms after cool down (48HRS) there were none until warmed up. Hydraulic level was up to where it should be. Kubota SUDT2 was used, as well as Kubota Filters. How do I move it to the Hydraulic forum?

Thanks,

Tom

 

[rswyan]

Per TractorData.com Kubota B7800 tractor information the rear lift is rated at 1,655 lbs so you were doing good to lift it at all.

Yup ... there's a very good chance that the hydraulics for the 3PH were running in relief for some - or all - of the time when he was trying to lift it or have it raised up ...

Probably not too good as far as fluid temps are concerned.

At a minimum, given the use, I'd drain the fluid into a very clean pan and have a look at it and take a sniff. If it looks or smells at all dicey, I'd probably pull the filters and replace them ... but save the old filters and cut them open with an oil filter cutter (or large tubing cutter) and have a look at what sort of debris are inside. Pull the strainer as well.

If the fluid smells cooked (burnt) replace it.

 

[bmwtomis]

I will try a full fluid swap today in the HST. If the 3point was running in relief for a while could I have done damage to the system? I hope not. Sounds pricy if i did. I will swap fluids and check back in..
Thanks

Tom

 

[bmwtomis]

Ok, so I replaced all fluids with Kubota SUDT2 and filters with no change. The fluid smelled fine, no hint of burnt oil. Everything else on the tractor is working good. I am not sure where to go from here.. Any help would be great.

Tom

 

[rswyan]

Ok, so I replaced all fluids with Kubota SUDT2 and filters with no change. The fluid smelled fine, no hint of burnt oil. Everything else on the tractor is working good. I am not sure where to go from here.. Any help would be great.

Since you were working with a very heavy implement on the 3PH, it would make sense that you might have closed the control valve (via the knob below the seat) to reduce the speed that the 3PH drops.

Check to make sure you didn't close it all the way.

 

[kubmehc]

I have seen my share of B7800 tractors lose prime to the Hydraulic pump for no apparent reason. If you have a hill you can point the tractor down or jack the rear as high as possible while it's running and see if it picks up prime again.

 

[rswyan]

I have seen my share of B7800 tractors lose prime to the Hydraulic pump for no apparent reason. If you have a hill you can point the tractor down or jack the rear as high as possible while it's running and see if it picks up prime again.

Interesting ... good to know :thumbsup:

I'd assume that you've also seen it on B2910's as well, since they are the same powerplant/transmission/etc ?

 

[bmwtomis]

I did in fact close the control valve below the seat. Huh, I dropped it off by the dealer this AM to have them look at it. I will stop by before they open and try the knob to see if that fixes it. It seems to hiss a bit when the steering gets hard . This maybe a relief valve I am hearing blowing off to soon,