Hello again, So this little 751 that I am trying to make a decent machine blew a seal on the tilt spool. Easy enough to get to, and easy enough to remove from the machine, but the photos I am seeing in my 751 service manual are just slightly ambiguous as HELL. I picked up a seal kit from Bobcat this afternoon, and there were three different sets of seals, I picked the set that came closest to representing the one that was still embedded on the inside of the bore, and went to work.....everything sounds like I know what I am doing up to this point......but that ain't even close to the truth. Here is my question: I found a o-ring on the boot side of the spool bore, but no o-ring on the cover(?) backside of the spool bore. Does anyone know whether or not there should be one on that side? There were three o-rings in the bag, which is also how many sets of seals there were......so I am thinking I only needed the one in the front? Anyway, I have my fingers crossed, thanks for any help.
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I'd leave it up. Even though you answered your own question, it's still gives us the information.
No harm leaving it there, it's all information.
There shoudl be a seal on the spool on both ends. The seal kits can be aconfising as they cover multiple models, not just the right amount of seals for a particular machine. It's a shame the bag of goodies doesn't come with instructions saying what model takes what seals.
There were three sets of seals in the bag, I took the existing seals out of the spool bore and matched it up as closely as I could to my options in the bag. Of course even though this forum has offered numerous warnings about not doing a thourough job, I thought I knew better and only replaced the tilt spool seals....and guess what happened? Yep, the pressure carried to the next weakest link: the lift spool seals! That was enough for me! I went back to Bobcat, bought the control valve seal kit and started replacing them all. All done. Everything is back in place and today I am refilling the hydraulic system. Any pointers on how to do a good job with minimal headaches when refilling the system? Thanks for any help
Isn't that always the way?
No real pointers, just re-fill and use it, You would have gotten minimal amounts of air into the hydraulic system, it will bleed out on it's own.
Well, that didn't go as planned. So I got the control valve bolted back in, lines on, filled the reservoir back up, drove the machine up to the shop door with the bucket still up in the air, knocked the lift arm brace off, went to lower the arms and bucket and nothing. I got the arms down by squatting in the compartment with the cab up, cracking open the line coming into the pressure relief valve, and pulling up on it until the teeth of the bucket was into the ground. Checked the BICS coil (someone had put a jumper from the traction lock solenoid to the BICS coil) got the connection back, jumped back in, fired it up and was able to lift the arms all the way up. Unfortunately, the arms lifted by pressing the right foot control (the tilt pedal) and then they would only work up intermittently. The left foot pedal had no effect whatsoever. When I would go to let the lift arms down, they would drop like a 10 ton stone....which was a little unsettling, never had that happen in a lot of years of running skidsteers. On two occasions, after I had let the lowered/dropped the arms I could not get the arms to go back up until I depressed the left pedal engaging it about half-way while pressing on the right pedal, also engaging it about halfway. Jumping off into the control valve was a major challenge for me, but I am this far....so no stopping now. Ever heard of or experienced anything like this? Any help would be appreciated. Thanks.
It almost sounds like your aux hydraulics are stuck on. Did you change seals in the aux hydraulic section?
There is nothing i can think of that shoudl cause this. If you just pulled the spool out, replaced seals and put it back in.
An air pocket could cause issues, but not like this.....
Thanks for responding Tazza. I replaced everything on the control valve. My machine is all hard lined, so almost impossible to swap out a line, but I guess it could still happen, so I am going to go check that. This model has two other blocks. One houses the lift bypass and the other, located under the reservoir contains the tilt lock solenoid, which I assume is the one that a lot of guys refer to on the control valve as the BICS valve or lock out valve? Am I correct in that assumption? Is there any chance that either of these or both of these blocks could cause any of this? They are the only parts I did not replace orings or back up washers on. It feels weird sitting in this machine and everything working backwards, but it reminds me of the lever you can throw on certain excavators for lefty or righty operators * Let me add one other detail in case I didn't mention it. I took the arms to full height and then tried to use the bypass to lower the arms, and they didn't budge. The only way they would come come down was by depressing the tilt pedal.
I read a lot about that aux valve being the culprit of many control valve issues. But I haven't come across any tests that could define whether or not its the issue?
The only test i can think of is to remove the quick couplers and start the machine up and see if oil shoots out one connector. A small amount is normal, but if it sprays, the valve is open.
That valve is the lockout valve. Safety device.
It makes no sense, as it was working before the seal change.
I have a grapple bucket, I will hook it up tomorrow and see what the results are. You are right and I am confounded by the same thing. Once you led me to the loose belt, the lift, tilt and drive ran smoothly...well, except for a steady stream of oil from the tilt spool....grrrrr. And then I get the bright idea of doing a through job like I knew I should have the first time. I cleaned a big spot out in the shop today, if I can't find something obvious tomorrow, I am going to pull it back out and work it again. Good thing about semi-retired and building a loader for your kid is you don't have to be in a race to get it done. I think this time I will document it step by step, maybe somewhere in this will be an answer another hack like myself might be looking for. If you see any photos or captions to my photos that aren't correct in the tech lingo, make sure and straighten it out, thanks for keep an eye on this thread.
A grapple bucket is even better, no mess to clean up.
Everything you have said makes sense, the "lingo" we use here can be different according to where we live, but as long as we all understand what we are saying, it's all good
I swear, the issue has to be something simple. A solenoid plug wasn't swapped by any chance was it? like powering the aux with the lift lock plug? just thinking about something that could happen by mistake when working in that area.
