hydraulic problem

[captdill]

I have had a series of hydraulic leaks, plus I lost a lot of fluid when I re-installed the back-hoe. Running it with low fluid most certainly put some air in the line, plus one of the (many) 5 gallon buckets of hydraulic fluid I bought may have been the wrong thing. It was red and was marketed as transmission/hydraulic fluid. Now my servos are working at half rate at best and the pump sounds like my Ford when the power steering needs fluid. Am I screwed?

[JWB Contracting]

I would unhook your backhoe hydraulics and connect them back together.

Your backhoe connections may look connected but they may not. Sometimes the quick connectors fail or jam internally.

if the oil is not circulating thru the backhoe circuit then you essentially have an absolute stoppage of oil flow in the system and you will blow your pump up, and this would explaining blowing hoes.

Check this first before continuing.

[captdill]

Maybe I should have said, the blade is also slow with same noise out of the hydraulic pump. That is independant of the backhoe system.

[CharleyF]

How is it independant of the backhoe?

The same pump runs pressure to both. The power beyond lines to the backhoe need to allow flow through them for the pump to work. I have experienced the couplings looking right but not being fully locked so there was no flow through them and it was clear something was wrong and there was noise from the pump.

Many people use trans/ hydraulic fluid in their system. I would be surprised if that was the problem, even if you mixed oils.

I would disconnect the backhoe hoses and plug them into each other and be sure they are good, then run the tractor and raise and lower the blade. Then I would reconnect the backhoe. If you are positive the connections are right and the problem persists with the backhoe connected then I would worry about an obstruction in the valves impeding flow.

[captdill]

Thanks Charlie,
My reasoning was that the fluid for the blade does not run through the backhoe connectors, so the blade should operate normally even if the connectors were not hooked up right, but it does not. Maybe I am missing something there, but I am relieved to hear the oil is not the problem. Some hydraulic systems are real sensitive to proper fluid. A college buddy put dot 3 brake fluid in his MG and within a day he needed to change all the seals. It can't hurt to look at the connectors, but I am leaning towards your obstruction theory. I suppose it has a filter somewhere? Maybe it did its job for too long.

Jeff

[KenP]

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[captdill]

I have straight JD 450 with a flow diverter valve which selects flow to either front mounted or rear mounted equipment, depending on the position of the valve. I do have the book, which is excellent for finding the location of the hydraulic filter, but no match for this site on pointers about how often it needs to be replaced, etc. Thanks for your help. Jeff

[Tigerhaze]

There are three manuals for the bare crawler: parts, service and operators manuals. There are also supplemental parts/operators manuals for the hoe and blade. I mention that because you may not have been aware of that.

The operator's manual has all the information on serviceable filters and service intervals- you may want to get that as well because it is helpful to supplement the information others can provide on here.

[captdill]

Thanks, I have the service manual and the parts list. Was not aware of the others. Another thing the books won't tell me is alternative sources for parts. Looking at the diagram, I doubt that the local NAPA would have that filter, but I do wonder which other parts I could save money by getting elsewhere, like engine oil filter, or the fuel pump I just replaced, etc.
Jeff

[Tigerhaze]

Hi Jeff-

There are a number of parts that can be obtained aftermarket- certainly the engine oil and fuel filters can typically be found aftermarket. Some parts, such as glow plugs and injector pump parts, can be purchased directly from the manufacturer or their suppliers without getting the markup from Deere. Most undercarriage parts for 450s can be obtained aftermarket.

Lavoy, the administrator on this site, is a good contact to start to see if a particular item is available aftermarket.

[captdill]

I changed the hydraulic filter. No help.

[captdill]

I lied. There were two filters, now I have changed both. The second one is a last chance screen as the fluid leaves the reservoir, and it was clogged, enough in my view to open any by-pass that might exist and allow junk to flow to the pump and beyond. I changed that filter and still no help. Is there a screen in the pump that might be clogged?

Would small solids pass through the pump and get caught downstream beyond that?

One gauge that still works is the hydraulic pressure, and it stays steady at mid range, I think it’s around 40, responding a little to throttle movement, but can’t see it dip under load. Where is it measured?
I can see the pressure hose tensing up when I actuate something and I think I am seeing full pressure back to the intake of the various valves. It was CharleyF who first said there was a chance of “an obstruction in the valves impeding flow”, and this will be my next focus. I will specifically focus prior to the first valve the fluid flows through, the diverter valve. If it was a single clog, and downstream of that point, either my backhoe or my blade would work properly; but neither does.
I will have to look closer at the schematic, or the tractor itself, to see if the thinking above makes sense. Need to better understand Why the hose from the pump only tenses up when I try to actuate something. How is the fluid circulating without load when nothing is actuated? It must default right back to the reservoir. I like this stuff, but need to move on to the projects I bought the dozer for. Stay tuned.

[KenP]

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[captdill]

Thanks. It will be a week or so before I can tear into it due to life getting in the way. I agree with you, the location of the restriction is pretty narrowed down at this point. That assumes correct diagnosis of a restriction rather than a blown pump. I don't think I blew the pump due to the strain you can hear (and see with hoses tensing up) on the system when something is actuated. I think a blown pump would simply continue its mellow way no matter what lever was pulled. I will post what I find to help out the next guy with the problem, assuming I find the restriction. I think the moral of the story will be to check those filters before the bypass opens up.

[jdemaris]

I don't think I blew the pump due to the strain you can hear (and see with hoses tensing up) on the sys.

I didn't read every word of all those posts on this subject, so I'm not even sure what machine you have. If it IS a Deere 450 crawler, then it has the a hydrauilc return filter AND a hydraulic suction filter. The return filter gets replaced whereas the suction filter is wire-mesh and can be cleaned.

A few notes - given free so take them for what they cost you.

If a Cessna (or early Webster Electric) gear pump was blown, you'd know it. In most cases it would push the front seal out, or crack the center housing, or blow the spider gasket. All would result in oil leakage. Also, if a pump is worn badly internally, it will pressurize the front seal and keep blowing it out.

Deere 1010s, 2010s, 350s, and 450s all use filter restriction indicators. Some of the fllter setups differ a little between dozers and loaders. That indicator will bob up and down if your oil is too thick. Deere had many problems with this set-up. First, the replaceable return filter was too fine and would blow off, or break the indicator in cold weather with 20W hydraulic oil. Note that standard HyGuard is also 20W. Deere recommended at that time to thin it with kerosene for cold starts below 30 F. Then later, Deere came up with a new filter with less mircon filtering that permitted somewhat thicker oil. At the same time, Deere came out with a second Hyguard for winter-use and they still sell it. It's 10W instead of 20W.