rScotty
Super Member
- Joined
- Apr 21, 2001
- Messages
- 9,583
- Location
- Rural mountains - Colorado
- Tractor
- Kubota M59, JD530, JD310SG. Restoring Yanmar YM165D
I think the short answer is, "I don't know where that dust came from." When I got that message from the JD hydraulic shop it surprised me. But they said they see that happening fairly often in boom and dipperstick cylinders on 310 backhoes. So I got to thinking, about that and how overall this machine has very little wear in spite of 6000 outdoor hrs...and now think that it was all clay dust.
A couple of factors lead me to that conclusion. That 2007 JD310 had excellent care, but it did spend it's first 8 years and 6000 hours before I got it living outside on the windy flat bone dry agricultural plains of eastern Colorado. That whole area of the state is is dusty like no other place I know of. Luckily there's no sand in their dust, it's basically all dry clay.In fact it's so pure that Colorado exports that clay as dried expansive clay all over the world. More on that below.
Out there that clay dust is everywhere. In every house and car and a cloud comes up each time you sit down. It was deposited a quarter inch thick everywhere in and on that tractor. I would take a panel off to check some wiring or such even inside the cab, and the clay dust would be an inch thick. At first I just used a mask, long paint brushes, and air pressure to blow it off.... but finally got enough off that I could go to vacuum cleaner & pressure wash in some areas. Because there weren't many oil leaks on this machine, the clay hadn't formed into true caked-on grease.
So how did it get into the hydraulic oil?? I just don't know. Maybe though a vent somewhere. Like I said, that whole area of the world is seriously windy and dusty. They really do export their dust as Colorado clay from there. It's used for drill mud and other places where you need a pure expansive clay dust. The clay is almost put bentonite with a smattering of other types of clays including montmorillonite.
And why does the clay dust deposit out in those two specific cylinders? Again, I don't know. It might be because those cylinders sit vertically most of the time.
And if so, it's also possible that there wasn't all that much dust in the hydraulic oil.... but what there was eventually all ended up getting deposited on those two hydraulic seals. That would explain why there doesn't seem to be a problem with the rest of the cylinder seals
Clay dust is a special kind of dust. Clay particles are very small - almost molecularly small - and the molecules are rather flat and shaped like dinner plates. Clay molecules are also slightly polar charged, so the clay glomes onto most fluids to become a very slippery substance indeed. Think of a pile of very, very small dinner plates with fluid between each plate. The fluid can be oil or water either one. In fact, that's how grease was made and some still is: Basically if you have powdered clay and add oil to it the product is called grease. So friction-wise it's not all that bad to have it in your hydraulic system. It isn't abrasive... rather the opposite. The badness happens when it falls out of suspension in the oil and packs in around a seal for instance. Then that seal can't move like it should. It's OK for a long while because at first it's just like the seal is being lubed with home-made grease, but eventually with pressure you get so much clay in a small area that it packs all those dinner plates together and excludes the oil. Then the joint begins to squawk and jerk as the cylinder rod moves.
BTW, exactly the same thing happens in pin & bushing joints in places like loaders and backhoe joints. If you use a clay-based grease it will eventually cake in there and the oil that made it a grease in the first place gets displaced by load pressure.... soyou end up with a joint that looks like it has grease but in reality it is just packed clay & doesn't have any lube to it. This can also happen even faster because of chemistry when different types of incompatible greases are used together. See "grease compatability" charts
As to why JD recommends an engine oil rather than their own hydraulic oil I don't know. I doubt it's a compatability issue. I've used both in this machine. My local JD commercial dealer is a sharp group of mechanics who like their science so I asked them. They didn't know either. But they said they knew of a lot of machines that used either or both without problems. According to JD's own literature they changed from HyGard trans/hydraulic fluid to engine oil in the HYDRAULIC SYSTEM ONLY. Starting with serial numbers
For the JD310G & 310SG at serial number 951253 and for the 315SG a little later. See page 3-1-6 & 3-2-8 in the Operator's Manual.
I just had to replace the hydraulic fluid suction hose on mine - a common job. It turns out that hose gets old and the ends begin to crack because of the hot fluid they see. Tightening the screw band won't help even though the hose body itself seems flexible & good. It is leakage because of splits under the hose clamps on the ends. Right under the cab. Easy way to replace it is to drill through it with a half inch auger, which drains out all the oil. You can catch it or replace it. HyGard costs so much I was going to catch mine, filter it, and reuse it. But engine oil is cheap enough that I just used new oil. Only downside to the engine oil I can think of is that I think they should have spec'd a lower viscosity multigrade for very cold temperatures.
rScotty
