Good day everyone! We've got a 160C LC, ~8000hrs on it, that's recently tarted having a very loud hydraulic whining, sounds like the main pump is cavitating. I'm certain it is because as the unit runs the oil gets foamy and in the sight glass and starts to get louder and louder. The unit never seems to suffer low hydraulic power and everything functions as it should, but it's noisy when using any functions. One thing of note is that it was pushing bush last winter and blew several lines several times and has been refilled with CNH Hytran Premium and has had all the filters changed. I've seen several posts on how picky these units can be with hydraulic oil type, is that to do with foaming? Has anyone else run into this on these units or similar units? Thanks for the help!
The Deere/Hitachi excavators take straight hydraulic fluid that needs to be zinc free. Mobil DTE 10 Excel 46 is a good choice. The Hitachi dealer will also supply you with their brand that I believe will be good for 4000 hours. Way back in the day John Deere was recommending the Hygard THF fluid for the Deere branded Hitachi's and ran into lots of hydraulic pump failures. They switched back to 46W after that. Hitachi never changed their recommendation.
Have you checked the piping and hoses for suction leaks? Loose clamps?
That was the first thing, one clamp looked like it had stripped and loosened so we replaced all the clamps on the suction line with new constant torque clamps. Also replaced the o-rings on the return filter cover and on the fill cap and cover. The orings on the fill cover were cooked due to the end of the muffler blowing out last season. Thought that fixed it but after a little work again it started making noise again.
Oil is zink free for sure, and has a viscosity between Hygard and Hygard Lo-Vis that the manual lists as the requirement. Just know that a while back CNH had foaming issues with regular Hytran in Patriot sprayers. It could be that the use of THF has finally caught up to the unit and caused a pump failure though.
Maybe the reservoir is not getting pressurized. When you release the hydraulic fill cap, is there a whoosh of air expelled from the reservoir? Also, when you changed the oil, did you flush the entire system? Maybe there is a reaction happening between the Zinc free oil and the Hytran.
*UPDATE* It seems that all the seals on the top of the tank were cooked and the tank was no longer pressurizing correctly. Replaced the filter cover oring, fill cover oring, all the seals in the cap and it is working as it should now. Last summer the end of the muffler blew out and operator continued running it like that for the day so that's probably what cooked all those orings as some of them were rock hard and broke apart on one half and perfectly fine on the other half.