341 hydraulic pump issues

[Linelife]

So, here's the issue. I was digging a hole and lost all hydraulics. Turned out to be the plastic coupler between the flywheel and the pump. Less than 2 hours later, same thing happens again. There was a 'hum' that started whenever I'd use the thumb which turned into every other control too, but it was very intermittent. Sometimes the thumb would do it, other times it wouldn't. I'm assuming that there's definitely something wrong with the pump that it wouldn't tear the coupler apart only after 2 hours, but where do I go from here? Is there a way to test a pump to see if something has a little play that's causing it to tear the coupler up? Thanks!

 

[mmsllc]

I'm not there with it too hear it, but it sounds like it could be a loose hyd. filter that is allowing air into the hyd. system & causing the system to cavitate (proper spelling?). I've seen a asphalt paver do that exact sort of thing right after a major service was done on it. It turned out to be a bad filter gasket on one of the hydraulic pump circuits. We found that issue easily when we found foam inside of the filter that came from the pump. We changed the filter & the problem was gone after about five minutes of run time. I'm hoping that is all that you need to do, too. So, pull your filter off.....Is there foam in it??

 

[Tazza]

I'm not there with it too hear it, but it sounds like it could be a loose hyd. filter that is allowing air into the hyd. system & causing the system to cavitate (proper spelling?). I've seen a asphalt paver do that exact sort of thing right after a major service was done on it. It turned out to be a bad filter gasket on one of the hydraulic pump circuits. We found that issue easily when we found foam inside of the filter that came from the pump. We changed the filter & the problem was gone after about five minutes of run time. I'm hoping that is all that you need to do, too. So, pull your filter off.....Is there foam in it??

Seems a bit silly to me to use a plastic coupler between a pump on earth moving gear

 

[mmsllc]

Seems a bit silly to me to use a plastic coupler between a pump on earth moving gear

I've seen it in other type of equipment. It seems to be a way to preserve the pump shaft spline or the engine when something locks up. As many guys on here have mentioned, BOBCAT has accomplished the same level of protection by using a belt to couple the hydraulic pump(s) to the engine. I think belts are more maintenance to keep them tight (& routine replacement), but when an engine or pump goes bad, they do not typically go bad. It really demonstrates the give & take relationship of using one part versus another.

 

[Tazza]

I've seen it in other type of equipment. It seems to be a way to preserve the pump shaft spline or the engine when something locks up. As many guys on here have mentioned, BOBCAT has accomplished the same level of protection by using a belt to couple the hydraulic pump(s) to the engine. I think belts are more maintenance to keep them tight (& routine replacement), but when an engine or pump goes bad, they do not typically go bad. It really demonstrates the give & take relationship of using one part versus another.

Generally after wearing in, i don't need to tighten the drive belt. Age will make them go bad, where as plastic may not.
The other thing is, IF you are ever stuck, you can technically use 2-3 single belts to get you running again, but a plastic coupler you are pretty well stuffed, dealer only.

 

[mmsllc]

Generally after wearing in, i don't need to tighten the drive belt. Age will make them go bad, where as plastic may not.
The other thing is, IF you are ever stuck, you can technically use 2-3 single belts to get you running again, but a plastic coupler you are pretty well stuffed, dealer only.

Very, very true. If he keeps breaking them, what do you think is causing it? A damaged pump that is locking up on him?? Only seems logical to think that something is stopping very abruptly to cause them to keep going out.I think he may need a new pump.

 

[7LBSSMALLIE]

Very, very true. If he keeps breaking them, what do you think is causing it? A damaged pump that is locking up on him?? Only seems logical to think that something is stopping very abruptly to cause them to keep going out.I think he may need a new pump.

the reasoning behind plastilic coupler? shear key.. if a relief sticks closed somethining has to give. preferably not a 5000..00 pump or 10.000 eng. first step inspect cyl rods for bends or flaking. ( source of contanintaiments) most likely you have a relief stuck closed. therebye strippining weak point ( most inexespenisve component). which is is good? now how to detirme which component is causining failure? you mentioned clamp thumb whatever. which should have a port relief. might be time to take to dealer. the 341 will also benefit from what I refer to as a hyd tune up. basicily flow check pumps . press check main and ports set to hi side of spefcations. the difference between 100 psi as transmitted to sticks will amaze you. springs get weak . pressures need to be readjusted now and again. so in closining my thoughts you got a relief that wont opn shearining weak spot . how would approach this is flow check pressure check and adjust accordingly

 

[Linelife]

the reasoning behind plastilic coupler? shear key.. if a relief sticks closed somethining has to give. preferably not a 5000..00 pump or 10.000 eng. first step inspect cyl rods for bends or flaking. ( source of contanintaiments) most likely you have a relief stuck closed. therebye strippining weak point ( most inexespenisve component). which is is good? now how to detirme which component is causining failure? you mentioned clamp thumb whatever. which should have a port relief. might be time to take to dealer. the 341 will also benefit from what I refer to as a hyd tune up. basicily flow check pumps . press check main and ports set to hi side of spefcations. the difference between 100 psi as transmitted to sticks will amaze you. springs get weak . pressures need to be readjusted now and again. so in closining my thoughts you got a relief that wont opn shearining weak spot . how would approach this is flow check pressure check and adjust accordingly

Well, I brought it in and had the pressures checked. Everything was where it should be. They told me that they had no idea what the sound was but probably nothing to be concerned with. Well, I don't buy that... I did a little more playing with it and once the oil warms up, it seems to do it more. While another guy operated functions, I was trying to feel where the noise was coming from. Seems to me that the inlet section on the control manifold is the source. I'm wondering if its possible that the flushing spool could be shaking back and forth making the noise that i'm hearing. I don't know a whole lot about hydraulics, so maybe I'm way off base. When it makes the noise, there's a definite vibration that you can feel in the throttle handle and most of the cab. I think if this is the source of the noise and vibration, then it would resonate in the cab being the manifold is bolted directly to it. Sorry for the delay, shipped out of town and then added a new baby to the family. Thanks in advance!!

 

[7LBSSMALLIE]

Well, I brought it in and had the pressures checked. Everything was where it should be. They told me that they had no idea what the sound was but probably nothing to be concerned with. Well, I don't buy that... I did a little more playing with it and once the oil warms up, it seems to do it more. While another guy operated functions, I was trying to feel where the noise was coming from. Seems to me that the inlet section on the control manifold is the source. I'm wondering if its possible that the flushing spool could be shaking back and forth making the noise that i'm hearing. I don't know a whole lot about hydraulics, so maybe I'm way off base. When it makes the noise, there's a definite vibration that you can feel in the throttle handle and most of the cab. I think if this is the source of the noise and vibration, then it would resonate in the cab being the manifold is bolted directly to it. Sorry for the delay, shipped out of town and then added a new baby to the family. Thanks in advance!!

for someone who is a rookie amazing yea flushining spool. what third section from left top port little shuttle.(memory not facts) fix was clean inspect . raise boom eng off key on console lowered. use accumaltor to lower boom . pushed trash back in. . like I said memory not facts but that was the issue.

 

[Linelife]

for someone who is a rookie amazing yea flushining spool. what third section from left top port little shuttle.(memory not facts) fix was clean inspect . raise boom eng off key on console lowered. use accumaltor to lower boom . pushed trash back in. . like I said memory not facts but that was the issue.

Pulled the flushing spool out and checked things out. Looks like new! We did a little more sound checking and we followed the noise down to the build up valve where it was louder, but that led us to the hose that goes to the cross port relief valve. I'm completely lost why while running the auxiliary hydraulics that oil is moving way down there, but again...not an expert by any means. From what I would guess, the cross port relief valve would be a relief while swinging the turret. Unless it's all part of a return system... I'm lost.

 

[melli]

BTW - are you accidentally hitting the thumb switch on backside of joystick? It turns thumb into a one way flow, for using a breaker etc.... When you get the hum, turn off engine and restart...if it goes away (hum), without playing with joysticks, especially thumb, you may have a problem with right joystick. I accidentally hit switch on backside of thumb switch and thumb would close, and hydraulics would labor...almost a humming noise....\ A long shot...