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Fieldtech59, Shop manager
Category: Construction and Road Equipment
Satisfied Customers: 111
Experience:  Construction equipment repair technician since 1986, JLG certified, Shop manager since 2006.
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I have a 2001 Bobcat 863 and I am trying to install a case

Customer Question

Hi Dan my name is***** have a 2001 Bobcat 863 and I am trying to install a case drain line to run a firewood processor everyone says put it in top of tank but noons says how. Please tell me you can help
Submitted: 1 year ago.
Category: Construction and Road Equipment
Expert:  Fieldtech59 replied 1 year ago.

Hello. 2001 863, most likely a G Series machine (triangle shaped headlights). If that's correct, the left and right drive motors both have a case drain line. You should see two large hoses connect to the left and right drive motors, and you should also see a single small hose connected to them as well, that's the case drain lines for the drive motors. Follow those small lines back from the drive motors and you should run across an aluminum cylindrical shaped canister plumbed in the lines, those are the inline case drain filters for the drive motors. Once the motor case drain oil passes through the case drain filters the lines continue on and terminate at the tank. The case drain filters are connected to the lines using #6 JIC hydraulic fittings. Simply disconnect the outlet connection of the case drain filter from either right or left drive motor, install a #6 JIC Tee fitting to reconnect the case drain line to the filter and connect your case drain hose from the firewood processor to the Tee fitting. If you have any questions feel free to ask.

Customer: replied 1 year ago.
Hi did you get my second message? It kept messing up... I hope u did. Rhanks
Expert:  Fieldtech59 replied 1 year ago.

Hmm, curious, second message? No, the only thing I see is where you stated you need to connect a case drain line, that's the only message I see and the one I responded to. Am I missing something?

Customer: replied 1 year ago.
We have an F series model and the headlights are square. The only one we see is about 12" below the reservoir and we teed in above the filter. Well then bad went to worse we blew a seal... We have been told by Hahn and Glen Halverson that we needed to gobin the top of tank but we were unsure how?
Expert:  Fieldtech59 replied 1 year ago.

I see, F series, right around 2000/2001 was when Bobcat was making the transition from F to G series, hard for someone like me to know for sure on these year models. But back to the F series, hyd tank located directly behind the operators seat, drive motor case drain line connects to the bottom of the tank and that's what you Tee'd into, no?

And "blew a seal", I assume you blew a seal on the processor motor? And maybe they're telling you there's too much pressure on the case drain line from the motor? Hence the reason they recommend the case drain from the attachment be tapped into the top of the tank? Is this a new attachment or one that has some age to it?

I'm beginning to see there's more to this than simply connecting a case drain line, the blown seal tells me something is going on here and is a new wrinkle to your original question. I've got to hit the rack, gotta work on a rock crusher on a job site tommorow, but I'll be back here tomorrow evening, jot down everything that's going on with this unit and we'll see if we can figure out what you need to do.

Customer: replied 1 year ago.
that's correct everything you said. OK well we were gonna work on it tonight but didn't wanna take any chances. 6 yr old processor. Ok Thank you. Will talk tomorrow
Expert:  Fieldtech59 replied 1 year ago.

What a day! Started out pulling the cylinder liners and cleaning the block on a 4 cyl Deere engine, then to a job site to work on a Powerscreen crusher, finished the day doing oil/filters on two Bobcats. But no, get home to find wife decided to re-arrange the house, just now sitting down at my computer. Arggggg.

I don't know what motor you're working with, the size of the supply/return hoses, the size of the case drain line that's fitted to the attachment motor. Also notable is the unit is 6 yrs old. Have you had it for that 6 yrs? Or did you buy it used and it's a 6 yr old machine. Is the hyd motor the original motor? Have you ran the unit for a period of time with no case drain line and you're just now (recently) fitting/installing one?

Customer: replied 1 year ago.
Hi. Thanks for getting back with me. We bought the machine used its a Hahn firewood processor. Its the hfp 160. Its a parker motor that runs the saw. One thing I noticed today is that the cylinder has fluid coming out around the shaft we have not ran it in several days all the other cylinders are dry... I am by no means a mechanic but since there is nothing on this machine anywhere I have done some reading and I do have a little common sense. Lol not so common anymore. No we did not run the processor at all without the case drain. But I am not sure if we put the line in the wrong place... We put a t in right above the filter. Everyone says go on on the top of reservoir but none says how. I have looked at every inch of both machines and all of this just seems for lack of better words stupid! There should be a much simpler way to do this to me.
Customer: replied 1 year ago.
The size of the line is a 3/8 inch hose.
Expert:  Fieldtech59 replied 1 year ago.

Ok, a little more info to work with. At this point I don't know if I'll ultimately be able to help with the scope of the problems you're having. We must consider, being a used machine/attachment, neither you nor I have any clue of actually how many hours the machine has been in use, how it was maintained, the previous machine(s) that worked the unit (pressure, flow, condition of the oil, what size case drain line was used), and how many components are original or have been replaced.

What we can do is work with what is common knowledge. First, case drain line. Gear motors do not require a case drain as they (by design) vent the oil used to lubricate the shaft bearings back to the return oil side of the motor, basically looping the oil. Other motors, piston motors, axial motors, require a case drain. Take a piston motor, the working oil passes through the piston chambers and pistons to do the work, controlled by a valve plate. But the other parts of the motor, such as the shaft bearings and slipper shoes, are not exposed to the oil inside the piston chambers, they would have no lube. So by design these motors are made to have a certain amount of "internal leakage" to allow lubricating oil into the entire housing of the motor to lubricate these parts. That's where the case drain line comes into play. Without a case drain, pressure would build inside the motor housing and blow out the shaft seal.

Knowing this, if you blow out the shaft seal, likely causes would be 1) excessive wear in the working parts of the motor, too much internal leakage, more leakage than the case drain line can handle and thereby building pressure inside the motor. Basically the motor is worn out and needs replacement. 2) Case drain line too small for the amount of oil coming out of the case drain on the motor. You stated you have a 3/8 line for the case drain. In most cases that's plenty enough ID for a case drain line so I don't think that's your problem, but with no real knowledge of that wood processor I can't say for certain, but that's typically plenty big enough. 3) Something obstruction blocking the case drain line not allowing flow. I'd say you've already verified this isn't the case.

So back to your machine and possible causes. Assuming the 3/8 case drain line is plenty big enough, and you tee into the Bobcat drive motor case drain line, I'm thinking that should work. If I'm not mistaken, that Bobcat case drain line is at least 3/8, near certain it ain't 1/4, so it's really not adding any restriction to your additional case drain. Moreover, the Bobcat hydraulic reservoir is vented, not pressurized, so the case drain is pretty much free flowing back to tank. Granted, since it enters the "bottom" of the hyd reservoir, the case drain from the attachment does have to overcome the weight of the oil in the tank, but if you think about it, would Bobcat run their drive motor case drains lines to the bottom of the tank if that were a problem? Not likely.

So, assuming your case drain line is plenty big enough, and assuming it's really not a problem to connect it to the bottom of the tank, after all, Bobcat does, then it's possible we're looking at a worn motor producing too much case drain oil. Again, I'm not familiar with the set up you have, but a typical diagnostic method is to test how much oil is coming out of that case drain line. Disconnect the hose that connects to the case drain port on the motor. Connect a short hose to that case drain port, a hose that you can drop in a 5 gallon bucket. Operate the motor and monitor how much oil comes out of the case drain on the motor. I can't say what "normal" would be for your motor, but just to throw a number out there, from small motor to large, anything from 1 qt a minute to max 1 gallon a minute going into the bucket would be acceptable, and that 1 gallon a minute is a lot. But if you're getting 3, 4, 5 gallon a minute out of that case drain line while the motor is in operation, that motor ain't happy inside.

I hope this gives you a little info to work with that will apply to your machine.

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