Somehow I unknowingly dropped a small plastic bag with 2- screws in my excavator hydraulic tank that was in my pocket when I was putting hydraulic fluid in. The inlet screen has been long gone so nothing except the filter inside the tank was there to prevent it from getting in the tank. The operator cleaned the filter and this allowed the bag and screws to get into the hydraulic pump and tore the hydraulic pump up. We pulled the pump today and found some of the plastic bag (evidence of my own stupidity) and some metal in the filter and hydraulic tank. Not sure how bad it tore the pump up but I sure was sick when I realized what had happened. The pump can be turned by hand so I am hoping that it can be repaired. We removed all the metal and debris we could see but really do not no what to do to make sure we have it cleaned properly.
It is really serious mistake.The screws will kill the hydraulic pump.But when your operator checked the filter,why he did not find the problem.
The hydraulics had already failed that was why he was checking filters to determine what the problem was, there was a noise in the pump / engine area also. The only clue we found was the small shred of plastic bag that was found in the filter thus tipping me off what had happened when I saw it.
:beatsme Good luck man.
hate to say it, but it's the worst thing that can happen to any hydraulic system, most machines never really recover from a hyd pump failure IMO
Even if the pump is rebuilt and the debris are removed? what other problems will surface because of it?
the big IF is getting rid of all the debris which can depend on the type of failure and/or if the machine has inline pressure screens after the pump then this will be a huge help, if not metal with be through most of the hydraulic system, valves, rams motors ect which is extremely hard to get rid of which may cause damage to other componets or operational faults down the line
Would the filter /screens be in the two big pressure lines that feed the main control valves if they are there? I did find some of the plastic bag (1"x2" size & 1- of the distorted screws ) in the large pressure side filter. I took the pump to a repair shop yesterday so I will see what they find inside. We did walk the machine a bit before we realized the problem so hopefully we can take the lines loose to the drive motors and clean out any debris.
As a Hydraulic Tech that has seen the results of pump failures on excavators, once you introduce that contamination into the system it is hard to get out, my suggestions would be to flush the system, its time consuming and expensive but it can help prevent failure of other components and the pump again. Depending on how bad your pump is chewed up, some of that contamination might have gone into the tank, I would say drain and clean your tank after you have gotten the report on the pump. Once it is back in the machine, loop as many of the cylinder hoses as you can and run the functions, there may be contamination in your cylinders as well that is hard to get out. I once had a client that didnt take my advice, he replaced both pumps on an EX700 Hitachi after a failure. They started up and moved about 50 feet and both pumps crapped out again, expensive mistake.
When you say to "loop the cylinder hoses" do you mean tie them together at each end or what exactly? How do you flush the system? Thanks.
JBGASH, when I say loop the lines I mean disconnect them and connect the free ends to each other to create a free flowing path for the oil to go when you activate that function. This will flush anything back to your return filters in the tank. Flushing can be done with your pumps on the machine or better yet with an offline filtration power unit, although this is very expensive as it means you will have to get someone in to do it. In your case if you have the time, I would say clean your tank, filters, and loop as many of the cylinders, track motors, and swing motor as you can and run each function. When you are done, remove your return filters and check them, cut them open and look for contaminates, if its big enough you will see it. Or you can do what most guys do and just take a chance, its your call, how much is the machine worth to you. Good luck with it anyway. Cheers
I will take your advice and loop the lines and at least try to get as much flushed out as possible, I actually have access to a filtration cart and will use it to. Thanks again for your help.
if you have those large pressure screens they should have caught most of the debris and will help no end with getting the system clean after a failure
I have not found the screens yet if they are there. I have the hydraulic schematic and am going to look it over closer to see if it shows them somewhere. Thanks
the damages Took the hydraulic pump to the shop, they found the screws that caused the disaster. It damaged the rotating group ends where the swash plates set against. It did not do anything to the gears, but did damage the pilot pump. The pump housing is OK and all the pistons looked ok too. It does not look to me that very much debris got away from the pump, because what we removed from it appears to be close to the damages we can see. Look closley at the rotating group cylinder ends picture and you will see the damages.
Ouch man, those rotating group barrels look like they are toast, from the pictures I dont think you will be lapping those scores out of the bronze. Can you get new barrels? Or Reman Barrels, they are probably not that cheap. At least you didnt seize a piston in a bore and rip off the shoes and push all of that into your hydraulic system. This really isnt too bad, if you found the screws thats a good thing, my guess is that you got lucky and didnt have a catastrophic failure that fully contaminated your system. Like I said earlier, clean the tank, change filters, I would still loop the lines at the track motors and swing motors, but your cylinders might be okay. Run all of your oil through your filter cart then take an oil sample to a lab or Cat to do a Spectro and particle count. They will be able to tell you what type of metal the contaminates are which will give you a hint as to what is floating around your system. I have seen worse and I have seen better, but I think you sort of got lucky on this one. Good luck and let me know if you have any questions.
The last picture is the screw pieces that were found in the pump, I also removed a piece of the other screw from the filter tank along with some of the brass. Repair place says that the entire rotating group comes as a complete kit so all components fit properly to each other. I have no idea what this cost will be and at this point do not even care, it is very sickening everytime I think about it, because enough things breakdown on their own, let alone me helping out like this ordeal. I guess that is why they are called accidents.....
I've been told that 70% of breakdowns are caused my maintainence, not sure about the figures but that have a point, don't feel too bad mate, things happen
I got a parts cost for the repairs to the hydraulic pump, they are as follows: 2- cylinder blocks @ $238.00 / apiece 2- swash plates @ $94.00 / apiece 2- 7 unit complete piston sets @ $258.00 / apiece Total parts cost: $1116.00 The piston sets did not get any damage and my mechanic says they could be reused, but I think it best to go ahead and replace them, what do you guys think?
I'd replace them if you have the funds. You have the thing completely torn apart anyways. Just my .03.
Yes I agree and will take your advice and replace them, after thinking about it, it would be stupid not too. The repair parts were considerably less costly than what I expected.
What hyd shop did you take your pump to? I'm about an hour north of KC and have been trying to find a good hyd shop for years.
Warrensburg Hydraulics, it is a small 2-man operation in Warrensburg, MO . However they referred me to Sunsource in KC, and were afraid to try the repair. Not sure why they told me they would to begin with now. I took the pictures at their shop, and have decided to try it myself along with a mechanic friend who has done these types of repairs before. He feels we can do it without too much chance of problems, because we retrieved the debris out of the pump along with the fact it was not a catastrofic failure. Sunsource in KC, MO sends all excavator pumps to Minnesota to be repaired. I did get an estimate from them also, it was $6000.00 Hopefully this will not come back and haunt me for trying it.....
Go ahead and replace everything you have new for, it will save you worrying about it down the road. As for Sunsource they probably didnt want to tackle a repair like this knowing it might come back to bite them if something blows later on, I have seen it before. They dont want to get into a fight about repair versus possible contamination that causes the next failure. If you follow the book you should be okay to put this back together yourself.
Hope like hell that no more debris has gone through the system. The finest of finest of debris can jam and damage valve spools/segments and then **** gets real expensive. But by the looks of things you've gotten away with it so far quite inexpensive considering what has happened.
Time will tell on what further problems this self inflicted wound creates, I hope for my checkbook,s sake they are minimal. But it is what it is and I will deal with it and make the repairs as they present themselves. One thing for sure, without the help and advice from many folks on this forum I would have been at a total loss with the situation, but instead I am going to make the repairs myself because of the knowledge and advice I have gotten here.
Good attitude mate. Hopefully it all works out fine.
Maybe I missed it but what make and model of machine was this? Wasn't there is a strainer on the intake to the pump in the bottom of the tank that should have caught the plastic bag before it got to the pump? I read that the strainer was gone but I took that to mean the strainer on the filler cap. I had Sunsource rebuild my pump. It was a mess. Oil was leaking from what I thought was the main shaft seal since oil was leaking down between the pump and transmission. Replaced that seal and still leaked. The guy at the dealer thought it must be the O-ring sealing the end plate on the pump and said it was "not a big deal to change". He said just stand the pump up, remove the bolts, pull up the plate, replace O-ring and bolt cover back down. Well when we took the end plate off the pump the whole thing sprung up, then after we replaced the O-ring we put the end plate back on and screwed it down. I thought the plate going down hard was just the compression of the spring that un-sprung when we removed the plate. But apparently when the guts of the pump sprung up from taking it apart something got miss-aligned. Before installing the pump on the machine we checked to make sure the pump turned over, which it did so we thought all was fine. After putting the pump back on the machine and starting it up, both sides of the pump shelled within seconds. Broke the piston heads right off both groups. Luckily no functions were operated so no contamination got into the cylinders or various motors. The brass returned to the tank. Drained oil, rinsed out the tank and intake line to the pump, changed all the filter, filled and ran machine according to instructions given to me by Sunsorce (I think it was run at idle for 30 minutes, then change all filters) and haven't had a problem since. Turns out that the oil was leaking from the piston that controls the swash plate. Sunsorce said they see pumps that leak there all the time and could have honed the bore and replace the piston for a couple hundred dollars. I just wish I had called them earlier before trying to fix it myself. I wouldn't take one of these pumps apart and try and put it back together if I were you. There is a lot of tolerances that must be maintained. Sunsorce is giving you the "worst case scenario" price. If your pump isn't that bad it will be cheaper. If I were you I would directly call the Minnesota repair facility and talk to them and see what they say if you haven't already. They are very helpful. They also have lots of used parts that they can maybe use to replace some of your parts that got messed so you don't have to purchase new ones from the dealer. I think the guy in Minnesota to talk to is Matt, but don't take my word on that, its been a few years back when I had my problem.
The machine is a early 90's Koehring 6620-LC-7. Yes, you are correct there is a filter in the suction side of the tank sump that has a spring loaded rod that is held in place by the filter top, but my operator removed this filter to clean it unknowingly anything had been dropped in the hydraulic tank. There is also supposed to be a strainer for the top inlet but it gone. You are correct the repair estimate was a "worst case." so talking with them and letting them know what was found by the other shop is probably a good idea. Thanks