I have gotten all the oils tested in a machine i want to purchase. The engine, left final drive, and Hydrostatic all came back good and nothing wrong. But the right final drive and hydraulic system came back with the following reports. Anyone got any ideas? It is a 2001 Cat 973C track loader.
Neither of these analysis are particularly unusual. Did you take the samples with the machine cold or had it been working with oil up to normal operating temperature when you took them..? That could affect the results quite markedly. The hydraulic system has dirt getting into it somewhere. Check the obvious things like tank caps that don't seal properly or a breather that's not doing its job right. Does the machine have any signs of leaks from the cylinder seals..? That's also a location where dirt can enter because where oil leaks out dirt gets in. The dirt that has already entered the system has started to cause wear, that's most lilkely where the aluminium (pump body?) and iron (pump gears?) is coming from. Solution is to find the source(s) of the dirt entry, fix them, then change the oil and filter trying to get as much oil out of the system as possible (don't just drain the tank) while doing so. If the samples were taken with the machine cold then it's not unusual to find a trace of water in a final drive. To give a "trace" in a final drive that size probably amounts to less than half a teaspoon of water. Most final drives don't have atmospheric breathers therefore any small amount of moisture that gets in there is trapped. It could be nothing more than the machine has been worked in extremely wet conditions at some point recently and a small amount of water has got into the final drive via the duo-cone seals. I'd do nothing more than get the oil hot, drain it and refill, then keep an eye on it going forward. It may be a sign that a duo-cone seal it starting to let go but if it is then it will most probably be a long process before the leak gets to the point where the seal needs replacing.
Nige, I often wished I could convince bosses of that! I was told by one that if the oil is coming out it will keep the dirt out too!. Problem is on a lift cylinder of a loader, for example, when ram is extended and wet with oil then the boom is lowered in float the seals in the head are seeing a vacuum as the piston draws oil in to make for the movement of the piston. Guess where that dirty oil on the ram goes! The joys of working for people with no mechanical aptitude!
Interesting thread. I've had the cylinder conversation many times over the years and have had to modify my thought processes. Most of today's machinery runs a system with higher than atmospheric pressure in the reservoirs meaning that there is always supposed to be a positive pressure inside the system. One would normally assume that would prevent contaminants from entering the hydraulic system through a leaking cylinder's gland seals. In the days of vented hydraulic reservoirs and low pressure high volume systems it could be true that you could introduce contaminants into the system through leaking seals in sufficient quantities and particle sizes to produce measurable wear. Those machines also lacked the safety suction feature that machines incorporate today. In the loader example which is a relatively low or maybe medium pressure system the thought process would indicate that dropping a bucket filled with material would be so fast as to create a vacuum on the rod side of a cylinder which would suck material into the cylinder. In point of fact all loaders today have the safety suction feature which opens up the return to tank side of the control valve to the rod side of the cylinder which would pull oil under reservoir pressure which is higher than atmospheric pressure still putting a positive pressure on the rod side of the cylinder. To make this simple, in modern equipment the cylinder will leak through the packing no matter which way you move it. That process can be modified by defective vent valves or other leaks that prevent positive pressure in the reservoir or problems with safety valves inside the system. The number one source of contamination of a hydraulic system is the person installing the oil. Leaking cylinder seals should always be repaired as soon as possible because of the hazards they create to personnel, the machine and the environment. One should look at the machine and maintenance practices as a whole when a properly applied oil sample program starts showing up with contamination.
I didn't know how to list which was what but the hydraulic system had the trace amount of water in it. This machine was used for installing sewer and water lines in new developments so it got in the mud and dirt. The dealership took the oil samples, when I looked at the machine there was no visible oil leaks anywhere, under it, inside it, on top, nothing. I'm assuming its dirt getting in from the cap and or breather. I did not find the breather vent when I looked at it, honestly never even though about it. The final drive I'm thinking its the face seal got mud packed in there and penetrated but I'm not 100% certain. Ultimately what would you guys say for the samples, the others came back excellent. The machine is priced right, and will see a lot less then 1000 hours a year.
I wouldn't let the less-than-perfect sample results necessarily put you off buying the machine. However I would imagine that they could give you potential negotiating room over the purchase price. If you can fix the root causes cheaply you have a winner, if not you still have advance warning of issues that might rear their ugly head further down the line. If the samples are reversed (i.e water in the hydraulics and dirt in the final drives) the root causes would still be pretty much the same. The final drive might respond to a good clean around the seals and an oil flush while the machine is hot using some 10W oil to get all the crap out of the corners.
Would a guy have to worry about a pressure washer pushing water into the final drive if put around seals? The ground this was used in is totally different then what I'm use to where GPM cleans off my mud, they need pressure to get the clay off. Unless I soak it with wd-40 first to soften the mud up at the seals. When filled with 10w would you lightly move the machine forward and backward to loosen up the sediment if any? I was thinking of using kerosene if it wouldn't hurt to just fill and drain.
If you pressure wash the outside of the final drives first, then drain & flush the oil, I wouldn't say so. Any dirt or water that you might drive into the compartment with the pressure washer you will then drain out with the oil.
That will be the plan if I do end up purchasing it. Have you ever tried seafoam in a hydraulic system to help get rid of water before a drain? The marketing sounds convincing that it would help remove water before I invest in putting new fluid in.
TBH I've never found anything that works successfully in removing water from hydraulic oil. Like I say in a system like your a "trace" of water is probably only equivalent to about half a teaspoon. I'd try to drain as much oil out of the system as possible, then fix whatever problem(s) you find before refilling.
Well I made an offer on the machine. Knowing what I'm getting into makes me feel better about the purchase. Hopefully it all works out.
We used to run into the problem of getting mud into final drives frequently on excavators and skid steers that were used in sloppy conditions. No matter how good the seals are they never completely prevent the entry of water and/or mud. Our procedure was to get the machine up to operating temperature and drain the oil, replace the oil with 10W or even a mix of 10W & diesel, then get the tracks off the ground and spin the final drives for 10 minutes & drain. Depending on how much dirt comes out of the final drive it may be necessary to repeat the process. As I said before, do all your external pressure washing before moving on to clean up the compartment internally.
This is one of the reasons I also adjusted my remarks about leaks, I started pointing them in the direction of being a fire hazard. Recall working on a 988 87A that had assorted leaks in the area behind cab that due to operator error and defective wiring in the warning system for parking brake operator drove off with brake applied. Guess he got the idea when flames started coming up the back of the cab!
Talk about common experiences! I saw the same thing on an 988B. I was sitting on a hill above eating lunch when the crew started up. We saw the black smoke before the operator realized the brake was still on.