Does anybody know the settings for the relief valves, the servo pressure, dipper boost dump valve etc..? My repair manual has all the necessary instructions on how to check and if necessary adjust the valves, but they give no pressure specs. They point to the technical data, which is nowhere to be found in the manuals. I am experiencing a variety of problems with my mini and since a so called professional had "repaired" and operated my machine it is a wreck. It started after he replaced the seal kit for the dipper ram. After working for 10 hours with the new kit the dipper started to sink by itself with the machine running or not. Since he had just put new seals for the dipper ram, he was looking for the problem else where and sure as hell found a fairly big chunk of metal in the dipper control valve. That is after he had determined that the dipper control valve was stuck and had "hammered" the spool back to its neutral position 2 times. It was determined that the dipper control valve had "internal" failure and a new valve for $ 1,4000.00 was ordered. In the meantime the professional kept operating the machine because if one was working quick enough the sinking of the dipper was hardly noticeable. After 10 more hours of working the dipper finally lost all power and we stopped working to wait for a new valve to arrive from England. We installed the new valve and the problem was the same. It was then that we looked at he obvious and blocked the rod side of the dipper and sure as hell the dipper came down rapidly. After dismantling the dipper Ram it was clear that something went terribly wrong when replacing the seal kit. The piston (head) had big chunks of metal torn out, the cylinder was scored beyond repair and it became clear that the piece of metal found in the control valve camo from the piston and not from the valve. After installing a new ram we drained all hydraulic fluid and flushed all the lines as it was likely that the whole system was contaminated with pieces of metal. Apparently we did not do a good enough job because now the bucket ram and the dozer ram are failing as well. The slew does not hold position and if parked on a slight incline the machine slews downhill even with the engine turned off. I have ordered seal kits for the failing rams, but am afraid that the rams might have more damage than the seals. Did not have the heart to take them apart yet. Furthermore, after operating for a while it seems that the oil is getting extremely hot and the servos start making a squeaking sound when certain functions are active. This seems to be happening when the oil is getting hot. I am operating in tropical climate and have put AW 46 weight oil, as recommended by JCB, after all the trouble we had. Now I am finding out that everyone else here is using AW 68 oil. I am assuming that the high oil temperature is caused by the relief valves not working at the proper pressures. This is a mess. If anybody has any encouraging suggestions and recommendations, other than buying another machine, I would really appreciate it.
How old is this machine ? s/no If you have had metal contamination go around the system you must stop and clean out the system and strip rams /valve blocks / hoses ect and put a flushing filter and cycle machine for some length of time but debris do like to hide. You may find debris blocking internal in the hyd oil cooler ,The slew sounds if the cross line relief valves on the motor or arvs on the valve block. You may be experiencing hyd oil to heat due to a relief valve or spool not completely closing causing just a seep oil to constantly passing . Hyd 68 is a good call for warm climates but does sound as you need to strip it down and go through the machine piece by piece and clean all components. You also have a PMV pressure maintenance valve with 2 speed track and hyd isolation on it this has shuttle valves and a relief cartridge in as well. If you can give a serial number i can have a look in the book for you.
Thank you Jeff, the year is 2005, 1780 hrs, and the serial no. is SLP08032E08999777. I am ordering the relief cartridge for the PMV as well. If I go through the trouble of cleaning everything again I want to adjust PMV relief cartridge and all the arvs to the correct pressures, but have no idea what they need to be. What I did not mention in my orig. post is that all services on the machine operate in a very jerky and sensitive manner. Also the slew seems to have no power at times, but if I operate the dipper that is already fully extended at the time the slew is speeding up.
That sucks...sorry to hear of your troubles. So, the seals went in arm, scored ram, and debris from that went to infect other parts. The mech compounded the disaster by pounding on spool. Hence, new valve section. Odd, the filters didn't pick up the debris...For example, on mine, the valve control block is split up into three sections, with Arm, Bucket, Aux and LH travel receiving oil from P2 from Hyd Pump (3 section pump). There is a main relief for that section, in addition to port reliefs for both sides of each function. P3 from Hyd Pump supplies the Swing, Blade and Boost sections. All these sections drain to tank via cooler, filter, then tank. The one issue I see on mine, is there is another route to tank (T2), but it goes through Swing pump first, but it has to pass an 'orifice' (0.88mm) to get to swing bi-directional pump, then to other hyd filter and tank (bypasses cooler). I can't help you with pressures for your machine, wish I could. I would pull port relief and crossport valves (on swing motor) for all of the infected controls to see if they have crap in them. That is fairly easy to do (no adjustments required, just inspect and clean if necessary). I assume you changed filters...I'd cut one open to see what it got. Maybe it got plugged and the filter bypass let crap to tank...once there, it can get everywhere. Do you have a hydraulic schematic?
I found the pressure specs in my repair manual. Don´t know how many times I have used the manual by now, but never realized that the specs are right on the page before the hydraulic schematics. From what I can tell the return oil from the rams is going through the valves before they get to the oil cooler and the filter. Speaking of filter: As soon as I start the machine the Filter cap is making a hissing sound, like there was air flowing through the cap. This sound has not been there before the trouble started. Another question: Is it possible that the accumulator not working has anything to do with the machine operating in a jerky fashion or is it only to relieve pressures in emergencies? Special trick or special tools to insert the Piston after replacing the seals? Thank you all
You know, I had that same problem...venting from tank. I don't think I have that problem now...haven't noticed it. Could be because things have cooled down here (winter approaching), or my adjustment on main relief and new oil. Perhaps, when the main relief on manifold (not the sectional 'main reliefs' on valve block) was too low, it got below the operational port reliefs of certain functions (in my case, blade, bucket and boom (rod ends))...that in turn caused the main relief to open (which vents oil directly to cooler-filter-tank). I also had foaming in tank - not a lot, and it would clear quickly...just surface foam. I am not getting foaming anymore since I adjusted the main relief. Getting rod into cylinder after putting on new seals...hmmm...haven't had to do that yet, but youtube has some great vids on it. I would suspect a cylinder ring compressor would help...
All i can say wow thats a lot of debris where did you recover that from? Air hissing from the breather cap could be a result of the hyds getting hot as you mentioned which will increase the pressure in the tank so the cap will breath. As far as resealing the rams simple task when you change the seals make sure to pull off the old seals of the piston on the ram rod to check and see if you have a dowl pin or a screw holding the piston before attempting to undo ,If you have a grub screw make sure a drop of loctite is used on there to stop it coming out and causing damage to the cylinder perhaps this was your original fault with the dipper (some of the 8050 had a valve mounted in the end of the ram rod check to see nothing screwed in the end has come adrift). When you have changed like for like seals the pressure seal will require putting in a bowl of hot water to assist once over the piston leave to cool if its stretched which they normally do if you have a piston ring compressor or just as good a hose clip but you will need to protect the seal so wrap something around the seal so as the back of the hose clip does not dig into the seal. Gently compress the seal and leave for 10 mins remove hose clip plenty of grease and enter the piston in the cylinder square and the push home the rod may need to tap it just a bit to start or take the ram completely off and drop the rod into the cylinder might be easier. On the slew dipper thing there is a dipper boost valve so when you dead end the dipper service it will supply oil from p1 so p1 will do dozer/180 swing/slew/dipper boost P3 supplies dipper/r hand track/boom boost/and hammer. In the pmv you have a little shuttle valve which oil will flow from either p1 or p2 if this is sticking will cause you pilot /servo issues with servo circuit and operation. Accumulator is only when machine is dead and the equipment is say in an up position it will allow the ign to be switched on and the accumulator will give enough pressure in the servo/pilot circuit to lower the equipment to a safe position. Far as the machine not holding on the slew it could be debris in the cross line reliefs holding the open into free swing. Setting the mrvs and pmv can be done by following you manual but you will need to have the arv test block to set the cartridges up or if you got access to machine shop they could make one for you not sure if you manual has a picture of this with a pressure gauge attached.
That amount of debris will take some cleaning out as you have already noticed that all the returning oil flows through the valve block back via the cooler , the cooler will have chunks stuck in there as well and i would be taking the tank out and see if anything has gone past filter to tank (bypass open) . In the tank there is a suction strainer on the out let to the pumps so check this as well . If debris have gone through the strainer be mindful that you have a variable displacement slew motor and main hyd pump so you may have damage to the slippers and swash plate scouring. On the return circuit back to tank you will find a check valve a long barrel nut looking think with an arrow on it with flow direction marked on check to see if this is also blocked .IIf you get it all cleaned out you can get a differnt micron filter element like what the machine was originally fitted from factory and why they are changed at 100 hr first service as to take out debris from build.
Wow JCB Jeff! I don't own one, but that was informative! Thx.
Thank you jcb jeff, the information you provided was really helpful and is much appreciated. I could not reply any sooner as I was at the Island where I am using the excavator. I don't have internet access there. No machine shop, no nothing. Just dirt and heavy equipment. I have to repair everything on site as it is extremely costly to move the equipment. Thanks again and I will post my progress as it happens. This will be a while as I am placing my order for a lot of tools and parts from the UK.
You are welcome if you need need more info just shout and good luck cleaning that debris out.
does anyone know the presure settings and procedures on a 804c. Iam limited to information where Iam located?