753 Metal flake is good for paint, but not hydraulics

[KyMadMan]

Trying to address some performance issues with my hydraulics. Rebuilt the lift arms last week. Looking at the hydraulic fluid coming from the lifts, I could see very small metal flakes in the oil as the container was sitting in the sun. These were not chunks, but rather a dust sized mixture. I know this isn't good. Planning to pull the engine and hydrostatic / hydraulic pumps. I know one if not both of these are in need of replacement or rebuilding. So first off, Mr. Tazza, I saw in another post you may have a source for replacement parts. I have Sauer / Sundstrand pumps in this unit. Would your source have parts for this brand? Secondly, and most important: What process can i use to clean out the rest of the system? I've read about pumping out through AUX but that is probably not going to remove all the particulate matter. Short of removing the drive motors, cleaning them and removing every hydro line has anyone done this extensive clean? My thought is to rig up a recirculating pump system and running diesel fuel through each line and then blowing them out with compressed air. I would also do this with the oil cooler and control valve. Am I over thinking this? Is some metal flake normal? I hate big projects that I make life harder on myself than I need too. What say you? Thanks in advance.

 

[rjitreeman0909]

I suggest changing your hydro filter and adding a filter in a hose loop fitted to the aux lines. Consider cutting open the old filter for flake exam. Filter must have flow capacity greater than full aux flow capacity. Oversize (GPM) is better to slow flow thru filter. Also add a large magnet in the oil tank. Again larger is better. Run machine at mid rpms and put aux in continuous flow. Ultimately all of your oil will flow thru the aux lines and be filtered. Take an initial oil sample and hourly. Similarly, check and clean the magnet. If practical put magnet in a zip lock bag. Cleaning it is simple. RnR the zip lock. Compare metal flake content over time. Should be a continual improvement, assuming the flake removal is faster than whatever is wearing. Make your repair/replace activities and run another sample for comparison. Even a full system dump will not remove 100% of contaminated oil. The filter procedure will remove the bulk of contaminants and then a dump refill should give you a clean system. To do better requires a complete system disassembly and component by component cleaning.

 

[KyMadMan]

I suggest changing your hydro filter and adding a filter in a hose loop fitted to the aux lines. Consider cutting open the old filter for flake exam. Filter must have flow capacity greater than full aux flow capacity. Oversize (GPM) is better to slow flow thru filter. Also add a large magnet in the oil tank. Again larger is better. Run machine at mid rpms and put aux in continuous flow. Ultimately all of your oil will flow thru the aux lines and be filtered. Take an initial oil sample and hourly. Similarly, check and clean the magnet. If practical put magnet in a zip lock bag. Cleaning it is simple. RnR the zip lock. Compare metal flake content over time. Should be a continual improvement, assuming the flake removal is faster than whatever is wearing. Make your repair/replace activities and run another sample for comparison. Even a full system dump will not remove 100% of contaminated oil. The filter procedure will remove the bulk of contaminants and then a dump refill should give you a clean system. To do better requires a complete system disassembly and component by component cleaning.

Thanks for that info Treeman. I'm going to have most of the hydraulic system apart (hydraulic pump, hydrostatic pump, control valve) so Im really looking for a way to just clean out the cooler, lines and possibly the drive motors although they may need to be rebuilt as well. If I didn't have the flake issue your procedure would be great. However, since something is making the flakes I feel I'd just be spending time and money trying to flush all the components that way.

 

[farmshop]

Thanks for that info Treeman. I'm going to have most of the hydraulic system apart (hydraulic pump, hydrostatic pump, control valve) so Im really looking for a way to just clean out the cooler, lines and possibly the drive motors although they may need to be rebuilt as well. If I didn't have the flake issue your procedure would be great. However, since something is making the flakes I feel I'd just be spending time and money trying to flush all the components that way.

Make sure to look at your case drain filters. Some metal while not good doesn’t mean you have to redo the whole system. I would change filters and fluid and run it for a while. I would look at the case drains for the motors as the can point to problems. If you don’t have operating issues I wouldn’t look for them

 

[Tazza]

Make sure to look at your case drain filters. Some metal while not good doesn’t mean you have to redo the whole system. I would change filters and fluid and run it for a while. I would look at the case drains for the motors as the can point to problems. If you don’t have operating issues I wouldn’t look for them

I assume you re-sealed your lift cylinders? not just the hoses?
Where were these flakes located in the cylinder? I'm hoping they were on the gland nut end (where the rod passes through). The nut is aluminium, so when you un-screw it, you generally get metal flakes. I hope it's that simple, and if so, as long as you cleaned it out pretty well before re-assembling it, you should be ok.
Checking the main hydraulic filter is a good idea too, cut it open with shears or something like that to not get metal inside it. When open, look for metal pieces, one here or there is normal, but if it's full of glitter, you have some work to do. As mentioned, check the case drain filters as well.
I have had machines that were bought damaged, they were fully pulled down, not a drop of oil was left in the lines (solvent and pieces of foam were blown through them with compressed air). I hope you don't need to go that far, but if you have actual contamination, you need to pull the lot down to find what is being eaten up causing the metal to get in the oil. If you simply clean the oil, and more particles are still being generated, you are going round in circles till the part finally stops working.

 

[KyMadMan]

I assume you re-sealed your lift cylinders? not just the hoses?
Where were these flakes located in the cylinder? I'm hoping they were on the gland nut end (where the rod passes through). The nut is aluminium, so when you un-screw it, you generally get metal flakes. I hope it's that simple, and if so, as long as you cleaned it out pretty well before re-assembling it, you should be ok.
Checking the main hydraulic filter is a good idea too, cut it open with shears or something like that to not get metal inside it. When open, look for metal pieces, one here or there is normal, but if it's full of glitter, you have some work to do. As mentioned, check the case drain filters as well.
I have had machines that were bought damaged, they were fully pulled down, not a drop of oil was left in the lines (solvent and pieces of foam were blown through them with compressed air). I hope you don't need to go that far, but if you have actual contamination, you need to pull the lot down to find what is being eaten up causing the metal to get in the oil. If you simply clean the oil, and more particles are still being generated, you are going round in circles till the part finally stops working.

Yes Mr. Tazza, new seals in the lifts cylinders. I did the repair leaving the cylinder on the machine. I should have grabbed a new container once I got the rods out for fluid catching. I'm not sure if the flakes were limited to the gland side or not. I saw flakes, and then saw more work coming my way. Do you still have a source for pump repair parts? I hope to pull the engine this week so I can get the hydro pump off and open it up. I'm planning to reseal the control valve as well. So that being the case most everything will be disconnected. I read your "foam, solvent, compressed air" method in another post after I made the original post here. What type of foam are you using? You mentioned diesel fuel as the solvent and I assume once it is blown out with the air any remaining residue is a non issue? The machine is a 1994 according to the local Bobcat dealer. It was originally purchased from them. I doubt much has been done as far as the hydraulic / hydrostatic system is concerned. It looks like it was used and abused before it became my headache. It seems to drive fine except for the whine when under load or slow speed. The tilt seems ok, but the lift has definite issues.

 

[Tazza]

Yes Mr. Tazza, new seals in the lifts cylinders. I did the repair leaving the cylinder on the machine. I should have grabbed a new container once I got the rods out for fluid catching. I'm not sure if the flakes were limited to the gland side or not. I saw flakes, and then saw more work coming my way. Do you still have a source for pump repair parts? I hope to pull the engine this week so I can get the hydro pump off and open it up. I'm planning to reseal the control valve as well. So that being the case most everything will be disconnected. I read your "foam, solvent, compressed air" method in another post after I made the original post here. What type of foam are you using? You mentioned diesel fuel as the solvent and I assume once it is blown out with the air any remaining residue is a non issue? The machine is a 1994 according to the local Bobcat dealer. It was originally purchased from them. I doubt much has been done as far as the hydraulic / hydrostatic system is concerned. It looks like it was used and abused before it became my headache. It seems to drive fine except for the whine when under load or slow speed. The tilt seems ok, but the lift has definite issues.

Parts places have been emailed to you.
The foam was simply packing foam from computer parts, not polystyrene that melts when adding any solvent to it.
I didn't find any issues with residue, if you are concerned, you could always use petrol (gas) as it evaporates, but it is a little more flamable, don't want you torching the place to clean a few pipes. The main thing to keep in mind is, COUNT YOUR FOAM PIECES, if you put one in, one must come out. I know i had some that i tried to push through and got stuck in elbows and took a bit of work to get out by reversing direction etc. This is really only an issue when using multiple pieces to fill a pipe. You don't want them being caught up somewhere when it's running.
Whining under load and low speed is normal, when you have the pump open, you can check for wear and go from there.
Remember, the engine and pump come out as one unit. 4 bolts and a hoses/wires and it all comes out as one piece. Once you have done it once, it's not bad to remove/replace. You will then have easy access to the control block.

 

[KyMadMan]

Parts places have been emailed to you.
The foam was simply packing foam from computer parts, not polystyrene that melts when adding any solvent to it.
I didn't find any issues with residue, if you are concerned, you could always use petrol (gas) as it evaporates, but it is a little more flamable, don't want you torching the place to clean a few pipes. The main thing to keep in mind is, COUNT YOUR FOAM PIECES, if you put one in, one must come out. I know i had some that i tried to push through and got stuck in elbows and took a bit of work to get out by reversing direction etc. This is really only an issue when using multiple pieces to fill a pipe. You don't want them being caught up somewhere when it's running.
Whining under load and low speed is normal, when you have the pump open, you can check for wear and go from there.
Remember, the engine and pump come out as one unit. 4 bolts and a hoses/wires and it all comes out as one piece. Once you have done it once, it's not bad to remove/replace. You will then have easy access to the control block.

Thanks for the info Tazza. Yes, had the engine out, managed to break the pump pulley and it is NOT an inexpensive part to replace. Grrrr. I'll be cleaning the entire system as I plan to rebuild the control valve since I'm so far into this project. I haven't cut the hydraulic filter open yet, but did see some of the tiny metal flake in the oil that cam out of it. I'm thinking if I have everything cleaned out except the drive motors, lift, and tilt cylinders any remaining bits will be filtered out once the unit is back in operation. I'll keep you posted and thanks again for all your help.