Hymac 370 Backhoe valve Block issues

[Rilouben]

Hello everyone.
I've been for 10years now th owner of a 370 hymac 370c.
I have soume issues with the valve block of the backhoe. Bucket dipper lifter.
The valve of the dipper ( that one in thé middle) is faulty. It makes the engine near collapsing with a huge airy noise.
I have check Many oRings but indon't know How to dismantle the valve itself to check its Spring or o'ring.
I would like to have the hydraulic specs of the valve block itself in case of excessive worn out of the valve block so i would be able to make it refurbished or i would fond a replacement item from an another Brand.
Thanks for replying.
Regards.
https://zupimages.net/viewer.php?id=22/17/kahw.jpg

[Whitlock 505]

Hi Jerome
I've got a 370c but I haven't got the specifications for the hydraulic valves. Are the oil levels correct in the tank?
If you go onto the download section on here there is a manual for the older 370 and that gives a step by step and troubleshooting guide for the hydraulic system
Hymac 370C workshop manual
Hope you get it fixed soon
Ian

[Rilouben]

Hello,
All the oil levels are correct. So as the filters that have been changed for less than 1000 hours of work.
Maybe that i should check the succion filter since i have worked in Moving earth ans diet and dust could have penetrated the oil tank. But i dont think it would résolve m'y problem. I have already dled thé manual work Book. I have Seen that i could check the slrv ans mrv valves. I must read it more carefully as my main issue is linked with one function of the backhoe loader valve block. The second ram which i have changed the seals. I will try to Switch two functions ( bucket ans dipper) so as tonne certain that my problem is located in the valve block.
For those of you interested i have a vidéo link of my problem that could give you a clue to help me in fixing it.
Nevertheless thanks for your help.
Regards.

[essexpete]

Can you post the video link?

[Rilouben]

Hello, here IS a video if my backhoe troubleshooting.
First i use fully thé controls and you Can Heart the engine RPM going down as well as this airy sound.. secondly i gently use thé controls, you Can see that the ram moves slowly but thé engine is not thriving.
Thirdly (full use or thé controls) the ram seems to move quicker until it seems to find an obstacle si the engine RPM fall down and thé airy sound Comes again.
By the way all seals of thé faulty ram are New ( décember)
And the smoke you see.comes from my cheminey....

Regards.

[dixie-normous]

Hi, have you checked the hydraulic hoses to the ram? I had a similar thing on a JCB that had a bad hose and it was bending half closed at the weak point when the ram moved
John

[Rilouben]

Hello. One of the two hoses has been changed a few years ago. I will try to dismantle the other one. But which method should i use to check if nothing IS wrong in it without changing it?
Thanks for your help .
Regards

[dixie-normous]

You could try swapping the two pipes over and see if it makes any difference

[Rilouben]

Hello, i have already swapped thé hoses when i changed the seals ans thé pin of thé ram. In fact it was a mistake from.me. thé ram did thé same but in reverse?
Regards

[dixie-normous]

I don't know the Hymac machine but i think your problem may be on the return from non pressurized side of the ram. It sounds like something is resticting the oil flow so the ram can't empty fast enough causing a pressure build up on the 'open' side. Maybe a bit of old pipe in the line floating around and partially blocking an oilway? Sorry I can't be more help