BH90 woes - what broke?

5030tinkerer · May 4, 2006

I fear that I broke a hydraulic seal on my BH90. I was using it yesterday when I noticed that the boom would no longer stay up - you can watch it rapidly leak down from the backhoe operator seat (likely less than one minute from "transport" position to laying on the ground). There are no leaks anywhere. Am I correct in assuming that a valve inside my hydraulic ram is the likely culprit and that the best course of action is to take the ram to a hydraulics shop? /forums/images/graemlins/frown.gif

Could this have been caused as a result of digging heavy, heavy muck clay with my new 36" bucket and that the weight was too much for it? If so, I thought that there were built-in bypasses to avoid over-stressing the hydraulics (that would cause the boom to simply stop moving and bypass the fluid when the hydraulics couldn't do it anymore)? Was I mistaken?

Bob53 · May 4, 2006

I was told by the dealer that you cannot rely on realif valves and these hoes will only do so much. He came out where mine broke and just told me need bigger hoe for work I was trying to do. I always thought would just be slower with smaller hoe, but not the case. Since i cannot afford to keep paying for new cylinders, i do not do anything that is the least stressfull on the hoe. Really not too sure of the new kobota BH75/90 models? last week guy on here lost 3 cylinders on the BH90. Not sure if the Woods are more forgiving or won't let you overdo it as much but I'd say might be worth try, expecially if you are in heavy soils or deal with rocks.
So from my experiance with mine i would never go about 12" bucket for a BH75 unless only easy digging. 36" on a BH90 might be pushing it to its limits and there does not seem to be a lot of limits bult in to keep you from overdoing it.
I'm getting my old clyinder rebuilt, it will probly happen again.

CTyler · May 4, 2006

Personaly I would think a 36" bucket is a bit much for that hoe or my Woods 9000 for heavy digging. What does Kubota say on the spec? I'm gonna guess 24".

I have 12 and 24" buckets and have done plenty of heavy digging with both and no problems. That includes hitting the relief more than a couple times. Obviously you try not to do that, if you do then let off right away. Pulling harder and body enlgish don't help /forums/images/graemlins/grin.gif

If you can't rely on the relief valve then that says to me its faulty or set wrong.

wushaw · May 6, 2006

I've had two different hoes, a Bradco 3265 on a B7500 and now a BH75 on my L2800.
I never broke the Bradco in 2.5 yrs use and it's sole purpose was stump removal and it did just that..a little slow and the hole was a little big.
I broke the BH75 (curl cylinder) I think Iam the only one that has broken that one but I think is was my fault , I don't do that anymore and so far after a few hundred stumps later and not doing "that" again all is still good.

If we cannot rely on a relief valve relieving pressure then what do we rely on before the machine destroys itself.

I don't hear any complains about a FEL bending cylinders and they run off the same pump as the hoe does. It has to be in the press relief circuit...maybe a bad batch????

I do not understand this problem with these hoes as this is not Kubotas first rodeo with building a hoe... /forums/images/graemlins/confused.gif

john_bud · May 6, 2006

Tinkerer,

There are 2 ways for the BH (or a loader) to act like that. First, there is an INTERNAL leak in the cylinder allowing fluid to bypass the packing. The second is that the loader control spool is worn out. I have $5 that says it's the cylinder packings. Here is how you check; First off you need to get a location where you can raise the boom up all the way and lower it down all the way. The cylinder has to be fully extended and fully retracted. Ok, you have that spot. Raise the boom up all the way. Take off the hose to the hydraulic cylinder that supplies fluid to RETRACT the rod. Then use the control to EXTEND the rod (the hydraulic bypass valve will operate, that's normal. There should be little to no fluid going out. My guess, is that you will have significant fluid without even using the control. If it passes that test, tighten up the hose, lower the boom all the way so the cylinder is completely RETRACTED. Then undo the hose that EXTENDS the cylinder and use the control to RETRACT. Again, there should be little to no fluid leakage.

I have been repacking my own cylinders recently. It's really easy (aside from the high torque on the piston nut). If you do pay to have it repacked, get a quote first. Then compare the repair cost to a new one from www.surpluscenter.com. Measure the cylinder in the fully retracted and fully extended positions. It's best to do this hydraulically with only 1 end on the hoe to get accurate numbers. Remember, cylinder specs are for the inside diameter. You can probably get a new one exactly like the old one for $2-250. Packing kits are anywhere from $15-60 depending on how the cylinder is made.

HTH,

jb

5030tinkerer · May 17, 2006

Update: I just had the opportunity to use the BH90 again (I've been out of town). The hoe worked flawlessly for digging a 55' trench 44" deep that was 36" wide. Any new ideas of what is going on? BTW, Kubota's spec on the BH90 indicates available bucket sizes up to 36". The 36" bucket that I have I purchased from my Kubota dealer. The dealer quoted me $100 parts and labor for repacking the cylinder, from drop off of of the tractor to pickup (i.e. they r&r the cylinder and test it).

5030tinkerer · May 17, 2006

Update: I just had the opportunity to use the BH90 again (I've been out of town). The hoe worked flawlessly for digging a 55' trench 44" deep that was 36" wide. Any new ideas of what is going on? BTW, Kubota's spec on the BH90 indicates available bucket sizes up to 36". The 36" bucket that I have I purchased from my Kubota dealer. The dealer quoted me $100 parts and labor for repacking the cylinder, from drop off of of the tractor to pickup (i.e. they r&r the cylinder and test it).

john_bud · May 17, 2006

Glad the hoe is working! $100 for a cylinder rebuild, including the R&R? That's a good price. What's the price for the Kit from Kubota? Labor time is probably under an hour.

jb

john_bud · May 17, 2006

Glad the hoe is working! $100 for a cylinder rebuild, including the R&R? That's a good price. What's the price for the Kit from Kubota? Labor time is probably under an hour.

jb

5030tinkerer · May 17, 2006

I didn't ask what the packing kit cost, but it couldn't be much considering the total price tag. The current plan is to just to keep using the hoe unless there is some reason to get it serviced at this point even though it is working fine now...