Hi guys. have a 336el with a bzy prefix. Anyways having some issues with the hydraulics. The swing function is very weak until you multi function. Right track is the same it’s very weak till you multi function. But the weird part is when you use right travel pedal it strokes up both pumps. Any help on this would be appreciated. thanks
Sounds like classic symptoms of a resolver (shuttle valve) issue. Don't ask me which one though .......... it seems like there are dozens of them on that machine including the pilot manifold. Every one of those plugs has a ball behind it.
You will need to check for codes before you do anything else. Unfortunately I don't have a video that shows how to get access to the diagnostics in the monitor panel for the E series machines.
I checked codes as I have cat et. No codes related to the issue.
Can you clarify, you wrote that the right track is weak but then you write when you use the right travel pedal it works ok?
Sorry the right track is weak. When you are multi functioning the power in the right track comes back.
I think Nige is on the right track. I'd pull the hydraulic schematic out, map out the resolver network and then operate the swing function and each function 1 at a time to see which function(s) bring the swing power up and which don't. Then repeat with the track and note the results. If you then follow the oil flow on the schematic through the resolver network you should be able to narrow it down to which resolver could be the culprit based on what the machine is/isn't doing.
The resolver network typically takes the highest pressure from any of the functions and routes it back to the pump, signalling it to stroke up. If a resolver is jammed up or bypassing, the pump won't see the correct pressure to signal it to stroke up for increased flow demands. When you run a 2nd function that requires higher pressure than swing or right track, that pressure is now the one signalling the pump to upstroke. That's why you're seeing the speed pick up during multifunctions.
If you want a copy of the Hydraulic Schematic just ask. I’ll send you a copy.
Ok, I think I know what your problem is. Inside the main valve there's check valves that can fail and then let's pump 2 oil bypass through the stick spool causing low flow/pressure to right track and swing unless the stick is active at the same time. Pull them and check, in your case I'm leaning towards the top one being the issue.
Remove manifold on the rear of the main valve to access it.
Did you cut filters ?
Any news, gonna leave us hanging?
Hi guys. We have recently checked all shuttle valves and everything looks fine. And we have checked the check valves in the main valve. We have ruled out everything and had the support from our local dealer and haven’t found the issue. they are sending a dealer mechanic out on Monday and started a dsn so hopefully they will find something. thanks for all the help
NFC2 relief broke and pounded out the seat in the valve. But its the relief on the bottom of the valve not the top
Interesting, never seen that before. But the nfc valves are in the top section, the checkvalves for pump pressures to the main relief are located in the bottom section however and looking on the schematics I think you can have the same kind of symptoms if one of those is broken.
Hey having a similar problem and found this forum, I have checked the NFC reliefs on top but where is the NFC on bottom I have checked over the schematic a dozen times! Also the check valves that are noted what are these check valves for?
Check valves in the bottom is for letting flow from each pump go to the main relief but not cross over to the other pump and vice versa What's your serial and symptoms?
336F RKB Serial - Will not track on right side and very weak on swing until you stick in and both track and swing work as it should!
Take a look at the check valves I highlighted in post#10, most likely the upper has failed but change both while your in there.
Sounds good, I will start on it Monday morning, should be a good time getting to them!
Had a similar issue over a year ago on a RKB 336F. Trash had the NFC relief on top hung open. Cleaned everything up and replaced the relief. It’s still never been 100% since then because I never could find where the debris came from so I will be looking into this. Swing and right track were the main problems as well. With the right operator running multiple functions at once you’d never know it but a lesser hand on it you can see a bit of a delay.
This is what was in it
Yep, that's most likely from the broken check valve. Here's a pic I had saved.
You’re thinking it’s from the top one that you called out in post #10? Been a while since I stared at all of that stuff on sis for that machine.
It was indeed the top one. Thank you very much for your help!
is this located on the main hyd valve behind swing
Before you start tearing things apart might I suggest you post your Serial Number on the other htread you created regarding a Diagnostic Code. I would suggest that you need to troubleshoot that side before going in blindly swinging wrenches, but that's just me...........
For sure! I had no codes on mine. Just lots of hesitation in the swing, left track and bucket curl.