Volvo EC15B swinging problem by arm move down

[wowe]

Hello,

I - or exactly my excavator - have/has the following Problem: When I move the arm down, the whole excavator Begins to swing. This is only by moving down. At moving up there is no Problem. And at moving down the swinging Begins only at a slow or medium move. I took a look to the mechanic, if there is something worn and has too much mechanical Play. But it seems, as this is not the case. What do you think? Air in the hydraulic? Let me know.

regards wowe

[Muz]

Welcome to the forum .. how long have you had the machine ? ..15B is not that old a machine ... was it always like this ?

[wowe]

Old machine? Hm... but younger than me. I bought it some days ago.

[ianoz]

With a highly uneducated guess , it sounds like a control valve problem , Or if pilot controlled , maybe a faulty lever control , if the two funtions are on the same lever .

[Muz]

Old machine? Hm... but younger than me. I bought it some days ago.

So theres a good chance someone has messed around with the hydraulics.
Do you mean to the the whole boom going up and down ? or just the dipper ? and I take it you mean the whole machine is slewing ? or do you mean its moving the boom off set ?

[wowe]

I made a video:

[ianoz]

OK , looks like what you where trying to descrble was lost slightly in the translation. I see Muz also thought the same as I . Only thing comes to mind after seeing the video is if it is fitted with hose burst protection valve , and it it causing the problem .
Muz may have a better idea now after seeing the video .

[Muz]

Yes we thought you meant swing as in 'slew' .. So the boom is just jerky when you are lowering it ...possibly a faulty/broken spring on the valve block on the return side of the hoist ram, ... but simple things first !! take the cap off the hydraulic tank (under the left arm rest) and look inside, is the tank full of frothy oil ?

[wowe]

I took a look at the hydraulic level. At the hydraulic tank there is a plastic cap, where the oil level should be. But there is no oil visible. I took a meter and did a measurement. The oil-Level is 13cm (about 5 Inch) below the should stand. I think this is a lot. I will refill the oil and then we will see. By the way: The reason, because I checked the Level not yet, was, that the seller said, the digger got a new service...

regards wowe

[Muz]

I took a look at the hydraulic level. At the hydraulic tank there is a plastic cap, where the oil level should be. But there is no oil visible. I took a meter and did a measurement. The oil-Level is 13cm (about 5 Inch) below the should stand. I think this is a lot. I will refill the oil and then we will see. By the way: The reason, because I checked the Level not yet, was, that the seller said, the digger got a new service...

regards wowe

Ok , the oil level should half fill the glass on the front of the tank with the boom lowered to the ground .. get it to that level and we go from there, it may be under filled or over filled, and the glass will look a solid colour either way

[wowe]

Is there a workshop manual available? I think to fix the problem I may need one. I am afraid that filling up the oil donīt fix it and I must disassemble something.

[Muz]

Can you make sure the oil is at the correct level and is not full of froth before we go any further ?

[wowe]

Can you make sure the oil is at the correct level and is not full of froth before we go any further ?

Oh yes - of course. But as the new owner of an "ill" mini-digger Iīm also feeling some pain and the strain to ensure that the defect disappears. I ordered the oil in the Internet, because I get it much cheaper in this way. But so I must wait until monday and thats hard. So I got the idea to ask after the manual. Hope you understand. I must learn "to wait" - ist sometimes not easy.

Best Regards wowe

[wowe]

Okay, I do not want to wait until next wednesday to get the oil. Only for testing I bought a 15W40 motoroil and filled the hydraulic up with 6 Litres. The whole hydraulic oil contains 33 litres. I strartet the engine and it seems as it would be much better - maybe ok. Then I greased the complete arm. But after greasing the jerky effect was back again. Surely the greasing was not the reason for the returned jerking. And the hydraulic oil didnīt foam up. So - now the easy things are done and the state is unchanged.

How will we continue the procedure? As an inexperienced digger mechanic - but I had become a car mechanic many years ago - sugggested 2 things:

1. I will remove all filters and meshes in the hydraulic circle and clean those which are cleanable.


2. I will change the hydraulic hose at the Joystick so up and down is changed. So I can see, if the behaviour has also changed and the jerking is at up.

3. Maybe I will try to reverse the buying. But the digger seem really in a good condition - except the jerky boom down movement.

Thanks for reply.

[Muz]

Can you make sure the oil is at the correct level and is not full of froth before we go any further ?

Okay, I do not want to wait until next wednesday to get the oil. Only for testing I bought a 15W40 motoroil

Well ... thats no good .. and it might be what someone has done already which is why I asked the question twice !

Your hydraulic system should only be filled with hydraulic oil like aws 32 or hyspin oil. Engine oil has very different properties and should not be used. It shouldnt harm your system, but to get it working properly the whole system should be drained, tank, rams, pipes etc, and refilled with the correct oil.

Hydraulic oil is designed not to be compressible, or harbour air bubbles despite being pumped, and also remain at a fairly constant viscosity despite varying temperatures. The movement of a fixed volume of oil is a critical function of a hydraulic system. If it mixes with other oils, small air bubbles often form in the oil, which are highly compressible, resulting in very variable operation of your hydraulic system. Sometimes you dont see any foam, but if you draw off any oil from the tank you can see its full of bubbles, and will cause all sorts of problems.