New member here. I've been reading and learning a lot. This site is a fantastic resource. Background - purchased a 2014 Volvo EC35c in November with ~195x hours (previous owner to me bought it w/ 1700hrs). This is my first excavator and using for personal use. Problem - I have put roughly 7hrs on the machine. One day after about 1.5hrs of operation the boom up/dn control became very slow. All other joystick operations were normal. I shut the machine down and did a once over and didn't see anything. Started machine back up and no the boom up/dn had hesitation, meaning I would push fwd/backward on the controller and for ~5-10 seconds the boom would not move. It would then move very slowly. The machine has an eco idle feature and moving the joystick fwd/back for boom would not kick the engine RPM up. The same left hand joystick moving left/right would kick engine RPM up and move as usual. The right hand joystick all functions were normal. Texted the previous owner and he said he never has seen that issue. I also learned that he never changed the hydraulic fluid on the machine. He had changed all other fluids and wrote the hours on the filters. The hydraulic filter has no hour or date markings on it. The filter is an OEM Volvo element. Unsure if its the original. Called a Volvo dealer - service guy told me to check a couple things (1) that the joystick plungers had full stroke, they did (2) check the spool valve as debris may be causing it to stick. I do not have the service manual yet (does anyone on here have it?) but do have the parts manual and was able to figure out which valve was for boom. I attached a picture of the valve body. The boom valve is the 2nd one in starting from the left. I removed the upper cover and was able to remove the spool. Did not seem stuck or any visible debris. I was able to fully slide the spool out. The spool would not fully go back in for me to reassemble the cover (assumed it was hyd fluid pushing back). I removed the bottom cover and the spool was able to be reinstalled. NOTE I did have to remove lines on valve body #1 and #3 in order to get the covers off of #2. Reinstalled everything and fired her up. The boom up/dn function now has no response. Previously the boom would start to move slowly after ~10s of holding the boom. Now the boom will not move no matter how long its held. *New* issue is the right hand joystick fwd/back now has the same hesitation as the left hand did. Hold for ~10 seconds and starts to move slowly. All other hyd functions work normal. I did not remove lines or disassemble on the new issue valve. Next steps: what I am planning but would like feedback from the community (1) pull the pilot hyd lines running from the joysticks to the valve body and blow them out with compressed air. I was thinking I should do all 6 lines at each joystick. Should I also do the high pressure lines going to the cylinders? (2) Drain all hyd fluid and replace with new and a new hyd filter. The fluid doesn't look bad but I'm not sure how old it is. My concern with this option is if the issue still remains I do not want to have to replace the fluid/filter again once it is finally resolved. She holds 16gal of fluid so I'm looking at 4 5gal buckets and a filter is like $100+. Open to any feedback/suggestions even if its take it to the dealer. One last think to note is I do not have a set of pressure gauges currently. Sorry for the long post was just trying to include every detail.
Before getting to deep into it. I would tee in a gauge on the pilot lines that control the affected function and make sure that the you are getting enough pilot pressure to the spool. It definitely sounds like a pilot pressure issue. Which the problem would be in the joystick since all other functions are working normally.
Good day I would abandon the air line that will achieve nothing follow what Paul suggested, attached some information that may help. Servo pressure is set Pilot pressure is variable according to lever movement. You have a load sensing system this means that when you shift the spool it gives a signal back to the pump to start working, dead end the arm and try woking the boom. Do you write novels for a living? Kind regards Uffex
Thank you PC and uffex on your feedback. No don't write novels, lol. Was hoping the details would yield a silly mistake I was making. I will pickup a pressure gauge to check pilot pressure as you suggest. Can you help me understand why some joystick functions work normally and some do not (bucket and rotate work normal, boom and arm are the issue)? If pilot pressure is the issue wouldn't that affect all joystick functions? uffex, can you clarify a statement in your attachment as I don't quite understand. "Most probable cause: There are a number of possibilities for leakage, we suggest a sensible approach is that of elimination. A machine that use’s servo pressure to release the slew lock is an example, try switching the lock on while observing the gauge. If the pressure loss recovers this indicates seal failure within the lock. A simple solution to servo multiple feed points is to plug and test these in turn, always please note the results." What is the "slew lock" and how to switch it on/off? Is it the same as raising the armrest up and down?
I suspect your joystick is the problem. The easiest way to find out is to tee in a gauge onto the pilot line at the spool. I only think that the joystick is not sending enough pressure to the spool since everything else is working normal.
Good day Canderso9 The information I attached is of a general excavator use, I did not intend to confuse some machines use servo pressure to release slew & travel brakes. Servo pressure created by the pump will be fixed at a set level, connected to the input port of the R.C.V. (Joystick). The R.C.V regulates the output pressure according to lever movement only two points of the output are fixed zero with no R.C.V. movement and that of full lever movement which should equal servo pressure. I hope this explains any misunderstanding. My comment was intended as a compliment re the novel I hope that is the way it came over. We have a video explaining the function, it will be released shortly if you would like I will see you get the link. The main pump in a load sensing system is idle until you operate a function, in your case it could be that the pump is not getting that signal. It is so easy to check operate the boom - bucket while you operate the arm. The arm will wake up the pump if the boom operates, it tells you directly that the boom - bucket are not signalling the pump. I will check the archives to see if we have any information on the Volvo mini, post if Im lucky. KR Uffex
Just a thought do you have a pattern change on your machine ?
Please see attached
Thanks again for helping me here. I did check a couple things while I wait on a pressure gauge to be delivered. Looks like I won't get until early next week due to New Year. - deadhead the boom and hold for ~20 seconds - engine never idles up and boom never moves - deadhead the boom and operate another joystick function - other function kicks idle up and moves but boom never moves in either direction - as previously mentioned the arm function didn't start hesitating until after I checked the boom spool - if I push righthand joystick fwd (arm extend) the idle kicks up and moves instantly. If I push righthand joystick back (arm retract) nothing happens until about ~7s of holding and then idle kicks up and arm starts moving. If I move RH joystick back while curling the bucket the arm still hesitates (it doesn't move instantly if the idle is already up). - above details happen at both 1/2 and full throttle Pattern change valve - I believe this machine has this function but not 100% as I don't have a manual. Attached is a picture of the lever that I think controls this function. My joystick functions currently are: LH: fwd/back = boom, left/right = cab rotate, RH: fwd/back = arm, left/right = bucket curl uffex, I would very much like a link to the video you are referring to as I'd like to learn as much as possible. Thanks
Good day The delay after disturbing the arm line may be a case of air in the line needs bleeding, I will try to find some more information. The illustration is not of the pattern change KR Uffex
Please see attached KR Uffex
See 23 Partial operation will give control problems
See attached
Good day This video illustrates the pattern changer take a look. Volvo Compact Excavators EC35C Features - YouTube KR Uffex
Hi uffex just wanted to give an update though there isn't much to update. I did receive my pressure gauges but a cold spell here in Michigan and being a bit under the weather has prevented me from working on the ex. It does look like I need to go to a local hydraulic shop to get a tee fitting to make it work. I assume I need to tee into the physical line to read pressure and there isn't a pressure port to use. Thanks for the video. I'll look for the pattern change lever. You are suggesting to change the pattern and see if the same joystick movements remain the issue correct?
Good day Canderson First may I suggest lets go for the common faults first - a pattern change valve that is not fully selected be it Iso or Std will give the kind of problem that you have so please check it out first. To test both servo & pilot pressure you w\1ill need a "T" connection on the hose connecting to your pressure gauge. Beneath the R.C.V. you may see the ports marked as in the illustration "P" is servo pressure in, testing this you need the motor running and the control lock out in the operative p[ostion. I will Check if I have any illustrations on file and send, if you have an problem to locate the pattern change just follow the lines. Kind regards Uffex
@canderso9 below is the parts drawing of the pattern change lever. and the schematic of how it works, hope it helps. item 3 in the parts drawing is the valve, the handle is on the end of the valve.
Good day Nice to see you participating good post. Kind regards Uffex
Morning Uffex, you guys are far more experienced at the practicle stuff, I just help where I can, thought those might be of use, if you ever need my help with helping someone just tag me and i'll help where I can with the Volvo stuff