Kubota Backhoe BH77 Cylinder Problem!

[@SOJ51.]

Daniel, Former F-18 Hydraulic mechanic USMC, had front landing gear fail to retract. Intermediate Level continued to send us improperly rebuilt hydraulic cylinders (even though they bench tested good). Fluid was bypassing internally of the cylinder during retraction. Once we received a properly rebuilt cylinder, problem was fixed. If you crack return line of cylinder and apply pressure you can see if fluid is bypassing the seals of the cylinder in question.

[@DIYMyWay]

Very puzzling. Looks like you’ve done everything you can, including rebuilding the spool valves. (I’m very impressed, BTW! That was a major undertaking!) I have a BH77 for my L3901 and it’s been a workhorse.

[@muxxor9492]

Is it possible to swap a hydrolic line with one of the valves that you know is working and see of the problem moves to another control.

[@andysworld2188]

I seen a video of someone whith a BX where the travel speed was not as fast as it used to be. Long story short the linkage got so much slop that when you engaged the lever it was not engaging the valve all the way. I've got the same BH but my tractor has 50 hours & the BH less than 2. Hope you get her figured out. Good luck.

[@jimgoodwin6294]

Personally, I'd start by fitting a pressure gauge to each line out the spool - that'll tell you whether its losing pressure within the valve spool... If it is, you've identified which spool and which also which side. Its very easy to guess that pressure is reduced but without a gauge you're guessing. I tend to think that the problem is within the cylinder. The seal on the end of the ram rod can often leak oil from one side to the other but not the other way round as the seal can act as a valve. This will make the cylinder feel like it has pressure on one side but not the other. Hope that helps.

[@jg413]

I couldn’t begin to say what it would be, I also have the BH77 and would like to see a follow up video when you find and fix the issue!

[@bobchiggs]

The video is a couple of years old so I assume you have it fixed by now. I was in the same boat. I spent the winter working on the thing, taking the control valve off and on more times than I can count. I ended up "hot wiring" the bypass valves (the big ones for the boom and swing - not the bucket or the out riggers) to get it to work. There are very small orifices, less than .020" in those things. You need the right viscosity oil. I notice that it is winter in your video too. If I can I'll post another comment I made on another site.

[@joeyoliver579]

Did you do a pressure check on the hydraulic system? Kubota (and Im sure other brands) are famous for setting the pressure below what the hydraulic system is rated for. If its low, you can get the correct (0.50 each) shims to get your pressure to the correct psi.

[@oby-1607]

Could this have been tested with a pressure gauge? My manual says this is the first step before teardown. I didn't hear that the cylinder was replaced after the dent. Try another cylinder (known good) to test.

[@campgas5344]

Sorry to hear about your problem. I have a Mahindra max 28 and had a similar issue with the loader. It was a piece of debris in the check valve on the loader valve. It would hold the load ok until I wanted to raise it up. The loader would lower instead of raise. The oil in the valve was leaking through the check valve internaly. I cleaned it out and problem solved. I know tracking down a hydraulic problem it is like finding a electrical issue on a car.

[@dirtbeard108]

mine developed a slow bucket curl after a few uses. culprit turned out to be a paint chip inside the control valve restricting flow.

[@MGMT200group3]

I have same problem did you remove the control valve to fix it

[@dirtbeard108]

@@MGMT200group3 the dealer picked it up and had it fixed in a couple days.

[@eddieb9110]

On the failure to lift the tractor... IF it is supposed to, check the relief valve setting (we are in the realm of gauges and know how for this). When you try to lift the back do you hear the pump sound change like the relief valve is opening and dumping to tank?

[@joshualane1195]

Have you tried swapping spool valves? Some of them are interchangeable.

[@jrw6868]

I bought a used bh77. After a while the boom would drop and not come up sometimes. The hyd oil was near the bottom of the sight glass. I topped it off and it worked fine. I also noticed when it would act up if I retracted other cylinders it would help. The pump never cavitated or made noise... Dunno but maybe its a tad low on fluid.

[@robbridges7810]

I had the exact same problem come to find out my trouble was with the switch under the seat that you push or pull I have two of them and one was getting stuck halfway open for some reason. I put a bungee cord on it and all good now.

[@scottfoster2487]

First step re assemble the whole backhoe! Check to make sure the tractor itself is producinging plenty of pressure,if the tractor is bypassing at the tractor the hoe will get to little pressure to run correctly. Also have you traced to make sure all hose are good, a smashed hose can cause alot of issues. Replace the quick couplers with a higher flow,seems dumb but sometimes a manuufacture installs the wrong ones.

[@CaptBill69]

Wow ... just recently learned my air compressor coupling have been low flow type the last twenty years ... and I just converted em to high flow for a paint gun session. Dang to think the same thing can be happening on new hydraulic couplings, and wonder how to identify high flow vs below par flow couplings. Thanks for Tip :+)

[@bobchiggs]

I bought a 3301 new and it howled and had problems from day 1. It wasn't broke so warranty wouldn't do anything. The backhoe finally wouldn't work (after warranty expired) and I worked on it all winter. I finally did my own testing and the viscosity was to thick compared to UDT. That's the problem with other "Kubota compatible oils" is the viscosity difference. Not all this additive super lubricating sales baloney. The valve assy on the backhoe has some orifices that are less than 0.020" (some metric dia?) and it won't flow thicker fluids. I suspect the same on trans lube areas. On my first oil filter change the filter was collapsed inside also. All I can figure is that the factory left in preservative oils in the hydraulic rams or something that caused the thicker oil. That will be the only and last Kubota I get. I stick with CAT. They use standard universal 10W hyd fluids. None of this "special" garbage and microscopic orifices that a Kubota has. A little more engineering and they could make these Kubota's universal instead of requiring special fluids. An "all synthetic" may have a low enough viscosity that it will work right, I don't know. Be aware that there are some very small orifices that have to flow the oil in a Kubota.

[@frankdove4869]

Hydraulic filters and your oil fluid is full that will create a problem also it could have a air lock somewhere in the system so bleed all your lines again and keep trying that and see if that solves your problem A friend of mine's got a portable backhoe on a trailer and it'll lock up and it's on a sandwich valve system and he reverses the two outside ones play with it for about a couple seconds we hook it up and everything works I wonder if that would work for you let me know if it does please thank you

[@dahill64]

Were you able to determine what the problem was? Also, is your tractor a L2501?

[@Blast357]

not a mechanic, but im pretty good with hydraulic. first off, I think you are right, the problem is in your valve. but probably in your relief valve (stuck open), not your main relief because all other cylinders work. but you probably have a relief valve directly on that valve. when the problem transfered to the dip cylinder, you knew the problem wasnt in the cylinder. I would get a pressure gauge good for 2500psi+ and hook it directly on the hose (easier than being on your knees at the valves...). you said you already disassembled the valves... but have you disassembled the relief and everything ?

[@Lupusharv]

Same issue with another cylinder after the hoses were swapped says it's in the valve, I would use a pressure gauge, betting it's in the relief portion of the valve, possibly have a bad spot in the ball or weak spring or just something stuck between the ball and seat. Hope you get it lines out.

[@Blast357]

pretty much my feeling too! the relief of that particular valve. not the main relief because every other cylinders are working fine.

[@stanleyjohnston5876]

Do you have the hydraulic Schematics of the backhoe? You may have broken spring in one of the valves or broken chunk of oring gotten into the valve bodies. Did you reassemble the valve body the same way you taken it apart. Just because the bodies look the same, internally they could be ported or spring compression differently.

[@simongreen276]

I am having the same issue with the boom cylinder on a b2650 with BH77. Did you ever figure out the issue or how to correct the low to no down pressure?

[@paulwiedeman4501]

Hi Dan, I also have a BH77 on my Kubota and sorry to say that I got nothing. The only problem I had with mine was the swing cylinder(left side) wasn’t swinging to full stroke under moderate load, right side was ok. Turned out to be the spool valve was sticking due to mice making a nest around valve assembly and the valve rod wasn’t sliding all the way in one direction. Got rid of the mice, cleaned up the assembly and worked fine. One question, could there be an airloc in the line at some point?

[@dragonwarrior4589]

I'm having the exact same problem. Left side is slow. I'll have to check that spool valve out. Thanks!

[@denisd4050]

If you did not find a problem yet. Touch the cylinder and see if it’s heating up more quickly than the others usually means your cylinder is bypassing. Or get yourself a pressure gauge make sure the pressure gauge is strong enough for the pressure. dead head the hose going to your cylinder if the pressure builds up it’s not your valve it’s going to be your cylinder and if it doesn’t build no pressure it’s the valve. Another way is fully extend your cylinder or retract remove the low pressure side of the cylinder and try the function you may get a bit of oil coming out of the cylinder that’s normal but a lot of oil is not make sure to cap The other line you removed. Good luck be careful

[@DanielWoodell]

Thank you have not fixed the problom yet and i will be trying th gauge as you have recommened.

[@denisd4050]

Its one Way I troubleshoot at work. It’s usually the easy way to find a problem good luck and be careful

[@thorerik678]

I think you mentioned that you lived in the Port Orchard area. Have you checked with Ben at Belfair Hose?

[@timminstraprs2169]

I’ve ran across a problem in the past where the lining of the hydraulic hose separates inside. Everything is working great, then the lining collapses, like a damper, it closes off the flow of fluid. Had me scratching my head for a few hours. The problem is usually intermittent, hope this helps out. 👍

[@CaptBill69]

Wow ... That must have had ya wondering for awhile for the fix. Nice to hear fix it stories as I am learning the hydraulics and fix options for an old Kubota D295DT w Backhoe I picked up recently ... on a good deal restoration roll ;+)

[@bobferranti5222]

I agree with some of the other comments, try swapping lines to another valve set and see if the problem changes, at least you can pin point the issue to see if it is in the valving or the cylinder. Then you can move on toward correcting the problem and have more focus. Also, even though you had the dented cylinder honed, that doesn't mean that it is completely round again, you could still be leaking pressure around the seals when it gets near the dented zone. i worked building hydraulic attachments for for lifts and if there was ever a dented cylinder, it was always replaced. Hope you get it fixed, you rely on it a lot and it is a great tool for you.

[@CaptBill69]

I got some lessons on hydraulics by reading the comments ... hope that issue is tracked down and fixed by now. It would be interesting to read and update :+)

[@DanielWoodell]

Look up kubota BH77 fixed I’ve recently posted a video about fixing it

[@joetterolison4093]

Aren't all those spools the same? Move them around to control different functions and see if the problem moves with the Valve

[@DanielWoodell]

A lot of input from viewers I was able to figure out what the problem was I made a separate video about the actual repairs turned out it was the relief valves

[@DeGauss73]

Is that just a furniture dolly you have the backhoe on to roll it around?

[@DanielWoodell]

DeGauss73 yup it works great as long as it’s in concrete.

[@sustainableliving880]

I had the same problem recently on the BH77 and resolved it. Is yours sorted?

[@DanielWoodell]

Nope I have not had a chance to take it back apart, and I have come up with all kind of reason not to use it just so I don’t get pissed that it’s still broken

[@scottmeister8980]

Last resort, check with Kubota. I just got a new L3901 with BH77 and the first time using it lost almost 2 gallons hydraulic due to a finger tight fitting from the factory. Under warrenty with only 18 hours on they fixed it and filled up the fluid. Just might be worth your time to check. And save the frustation of racking your brian.

[@daveshawn9865]

Have you got the problem figured out? I had identical issues with my BH77 and was able to fix it by taking apart the pressure relief valves, cleaning and putting them back together. I believe there is a way to put the valve back together to make it operate correctly. Great videos. I am a neighbor of yours probably 10 minutes away bordering Banner Forest.

[@DanielWoodell]

I have not had time to work on it in the last few months because i have been building a house. But this winter i will be taking back apart. And yes we live close. I grew up riding dirt bike in banner forest, cant do that anymore but. i take my daughter out walking in banner everyone in a wile.

[@daveshawn9865]

@@DanielWoodell Try assembling the pressure valve dry (no oil) and give that a try. I was assembling the valve with oil and couldn't get the boom to operate correctly. The pin that is tapered on one end and the other end fits into the recess of the adjusting screw when oil is in that recess the pin will not seat all the way (hydraulic lock). This will force the valve close. It's just a theory but it worked for me.

[@micahjones2568]

I am having the same problem, did you figure out the problem. I have already replaced the cylinder?

[@123decoeli]

I'm wondering if you can explain what you did to clean the pressure relief valves. Mine only plays up when it is cold, for a minute or two, but I'd like to nip it in the bud. Can they be dismantled?

[@daveshawn9865]

@@123decoeli The valves can be disassembled. I did that numerous times to only have the valve work for a short time. I switched valves with another to verify that it was actually a valve problem. I bit the bullet and bought a new valve spool and never had an issue since.

[@rumsiker]

i have the Kubota 1985 l3750 with l4540 backhoe 50hp never a problem till summer of 2019 , my mistake , i usually check every bolt and nut each time before use to make sure all good and tight and no leak liquids ok , if something started to loosen up usually can tell by the rust around the nut or bolt or leaky connection, so as i was using the hoe the through bolt at top holding in place the pin going top to bottom hinging the backhoe backed off so the pin move up out from under and the result was i bent everything the hoe want down sideways , whined up buying another good used chases and by myself at the age of 80 i take the sucker all apart and swap it , what i am trying to say here is in doing this i came across all of the problems mr Woodel encounter , so air in the system , mixing the hoses , hydraulic level is , is the key, if all working and one cylinder not it is not pressure.but dont overlook the hoses sometime the hose go bad inside swells up and stops the flow of fluid , remove both end and blow through it once you blow out the fluid in it, it should blow through easy

[@kroy-rz8cd]

so what happened?

[@felixnungaray3253]

Crack the line see if pressure comes out. The cylinder could be bypassing

[@OutdoorswithErik]

Dang dude, should I not consider a backhoe?

[@DanielWoodell]

Outdoors with Erik well it worked great for 3 years, but I’m considering trying to sell it as is and then buy an excavator.

[@joeyoliver579]

@@DanielWoodell Keep the hoe (fix the hoe) and get an excavator. They work very well together.

[@ArthurDentZaphodBeeb]

@@DanielWoodell Yeah, get an excavator - those tractor attachments are little better than toys. I'd probably get a track skid-steer as well - for a small contractor, you can do a lot of work with that combo.

[@michaelmactavish1728]

@@joeyoliver579 it be covered with 6 year warranty

[@campgas5344]

Your tractor dont look that old. Have you had a kubota dealer look at it. I would not think it was the valve. Not much that can go wrong in there. Usually they go bad if moisture gets in and freezes. Sounds like a bad cylinder. I just had to put a new stabilizer cylinder on my mahindra backhoe. It just wouldn't stop leaking, even after two sets of new seals. I found a hydraulic company in Kentucky to modify a stock cylinder at a fraction of the price of new. Keep us informed. I know how frustrating it can be!!!

[@drummer57]

Check the pressure relief valve they are on the end of the spool section they mite the problem good luck

[@felixnungaray3253]

Its electrical, or the valve is sticking

[@rumsiker]

Yes he have done everything he can as far as he know but the problem exists because he is not a hydraulic mechanic and he missed the problem and by removing the hyro valve he created another problem, i am sure he put one of the hoses on crisscross the hoses are usually numbered if not you should number them before removing , the second problem he may have is that the system may have air and must be bladed , if the hydraulic in use is making humming nose defiantly should be bled , stretch out lay down the hoe and crack each fitting at higher end till you get a good squirt of fluid then raise it but make sure bucket is on ground and do the same with the other end of cylinder and must tighten fitting before stops bleeding remember fluids sick their own level air is always in the higher end of cylinder good luck

[@bertarednecks3773]

Check the pressure on either side of the shitty cylinder and a good one and then borrow a flow meter

[@bryannoback2274]

I know one thing for sure is DIRT and hyd. don't mix.

[@effthegop]

I love tractors. I hate tractor repair.

[@danfreitas7905]

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