Couple of questions on hydraulics. The bucket cylinders on my Cat 931B used to weep a tiny bit right around freezing temperature but not when it was warmer or colder. It was around freezing today and they were weeping way more than usual, actually dripping oil onto the boom. Anyone else ever experienced this? I guess I need to reseal them but why they weep so bad at freezing temperature? The other question is concerning steel hyd. lines. The lines for my 4 in 1 bucket are bent pretty bad from branches and frozen lumps and stuff falling over the top of the bucket. Can they be heated to get them somewhat straight or does it just weaken them? I need to redo all the lines on the back of the bucket too. Maybe heating them to get them the right shape to make a template for hyd. shop would be a better idea? I priced out the bucket lines from Cat and I'm scared to see what the lines down the boom would cost.
The seals are worn and don't have much squeeze left and in cold weather they are too hard to be energized. Tubing on american or japanese machines is usually mild. So as long as you aren't taking 180 to 0 you should be fine. How much were the tubes and what was the length and how many bends did they have?
It's just odd that they only seem to weep around 0 deg. C. but now they're leaking quite a bit. It was a few years ago and I think just to replace the 2 long lines on the back of the bucket close to $400 from Cat. They had some silver soldered connections. Maybe someone has a pic. of how the lines down the boom are bent where they hook to the bucket hoses. There's a hyd. shop that can bend the lines but I need to make an accurate template first.
Just letting you know may be time for a repack. Local hyd. shop made my 4/1 feeders for less than $200
I would try and get a seal kit from Cat though. I pulled a big cylinder off a machine and the hydraulic shop installed generic seals from their inventory. Thing leaked worse than a sieve when I put it back on when it was just a little dribble in the first place. Ordered the proper kit and had it redone. It was good after that.
You might check the diameter of the cylinder rods if you tear down the cylinders for repacking. Over time the chrome on the rods wear off a little at a time. It might be time to have them re-chromed.
The cylinder rods look good so I think it's just an age thing. The machine is an 86. The sad part is the cylinders leak out the end but take quite a while to creep down. Adding some oil occasionally isn't too bad but when oils covering the boom it's time to repair.
I'm weeping with you, Welder Dave. In the same boat with my 955K--all 6 cylinders dribble (4-in-1 like yours), some more than others, but all due to just occasional use in 20 some-odd years by the previous owner. As to the temperature thing--when it's warmer, the seals are more pliable and seal a bit better. When it's colder (below freezing), the oil is thicker and doesn't flow past the seals as well. Somewhere in the middle (for you around freezing), the seals are loose and the oil flows better so it leaks more. I look forward to hearing tales of the repair and seeing some photos as well! (but please downsize a bit for us folks in the boonies on molasses-in-February slow internet speeds!). Good luck! Hope you won't need it, though.
I guess the bucket cylinders are easier to get at than the boom cylinders. One of the 4 in 1 cylinders weeps but I don't use it too much. The bad part is no matter what you do you always end up with a mess. Not sure if I'm going to pull the rod out or just take the cylinders in to be resealed. I think the cylinders use a bolt to hold the piston instead of a large nut but I don't know if the bolt is tightened as much as the nuts usually are. I had to have a cylinder on the backhoe repaired because the bolt ripped the threads out of the rod. They said the rod had a slight bend so they straightened it and I suggested using the next size bigger bolt and drilling the piston hole bigger. That saved me a couple hundred bucks over having a new rod made but after straightening they said they had to polish the rod etc. so $1300 later I was back in business. The bucket cylinders look good and just need new seals so hopefully won't cost a small fortune. The machine has about 5600 hours on the meter which I think may be close.
Hello welder Dave , I had to make new steel lines and seals for my 931b , it was not to hard but took a few hours and a real do on a couple . there is an old thread .
I was hoping you'd respond wosama931b because I remember that thread but couldn't find it. I'll keep looking. The lines down the boom where they go under and in toward the bucket I'm not even sure what they're supposed to look like they're bent so bad. No kinks though, they're still round so that's why I was wondering if they could be heated to get them close to original. The lines on the back of the bucket I need to replace everything. Some people rave about 4 in 1 buckets but I can see why some users will never have them. Not that the bucket is bad but the lines are just too vulnerable if you're around tree's or have lumps go over the bucket, etc.
I think the hardest part is flairin the steel lines, I used a harbor freight bender, and had a heavy table with a hole that the tubing could go through. I did have to purchase new fitting. It was a learning experience for me, the old lines may have a brazed fitting, that can be reusable. Good luck Dave.
I took measurements and my old lines to the hydraulic shop I deal with most often. Then mandrel set the flares/new tube nuts and made the more demanding bends where I used of all things a conventional conduit bender to make the minimal radius curves. Cost was cheap compared to time dinking around with trying to save the old ones. And I too am finding the 4/1 MP a little less and less convenient or handy. May, providing I can get the trans overhauled build a removable grapple for mine.
In reply to the hydraulic lines. My 931b has hard rigid pipe running down the right side loader arm with flexible hose going to distributing manifold on back of bucket.The pipes on bucket are original.