New Holland 555 E Hyd oil over heating where is relief valve? & regeneration check

bruce0777 · May 18, 2014

New Holland 555 E Hyd oil over heating where is relief valve? & regeneration check

I just bought a 1996 new Holland back hoe with only 2900 hours . Seems as though the backhoe section working it was fast to operate but very weak to lift and pull just not enough muscle After about 45 minutes of running the hydraulic oil heats up to 160. Sadly the hot hydraulic oil light or buzzer alarm will not come on at high working RPMS they only comes on when you idle the motor down. The hydraulic oil in the tank looks like brand new out of the can cleanest I have ever seen. I checked the hyd pump pressure and it showed great pressure front and back of pump. I called a hydraulic guy to help me out and I pointed out how the hyd pump had a deep whinning noise. So we changed both filters the big canister by the pump and also the one in the hyd tank. The whinning noise got softer and the backhoe still had a power loss. He called another hyd guy and found out new Holland is known for a pump cavitation problem and the cure was to remove the hyd filter from the hyd tank. So we pulled the tank filter back out and the pump ran smooth as silk. Still the power loss and the over heating in 30 minutes or so of running to 140 degrees after 45 minutes it goes to 160 degree . I called the hyd guy and he said he was going to research it and that was over a week ago. So I down loaded the hyd repair book and it said loss of hyd power is due to the regeneration check valve . where is this??? and over heating is due to setting of relief valve to high or to low. Where is this???? And which way do I adjust the regeneration check valve higher or lower that is if I ever can locate it? I was told this may have been a rental company backhoe being it was painted green. And rental companies are known to turn down the hyd pressures. Any help would be great to say the least.

Bigfoot62 · May 18, 2014

Re: New Holland 555 E Hyd oil over heating where is relief valve? & regeneration chec

I'm not familiar with that specific model, but most industrial TLB's have the relief valve located on the loader valve assembly.
It's possible that you could have another relief valve on the backhoe valve assembly.

J_J · May 18, 2014

Re: New Holland 555 E Hyd oil over heating where is relief valve? & regeneration chec

160 degrees is not over heating.

200 degrees would be running hot.

If your pressure is correct, then you have to look at the cylinders for piston seal leaks/bypassing. Maybe valve spool leaking. Did you switch hoses for any of the cyl.

Some BH have 4 or 5 reliefs in them. the BH main valve relief, and then you may have work port reliefs.

Some BH valves do not have a main relief and rely on the tractor hyd relief for protection.

Did you check all BH cyl to see if the relief valve would activate.

What pressure did you read on the gages.

bruce0777 · May 19, 2014

Re: New Holland 555 E Hyd oil over heating where is relief valve? & regeneration chec

Thanks for all the help on this issue Guys. Yes hyd pressure was great off the front and back of the pump What ever the book said I needed I had it plus some from memory around 2300 PSI at 1500 RPM's. When I first bought it had a lot of bad hyd hoses on it and one busted in the first 15 minutes of running the backhoe, so I Replaced them all on all the back hoe end cylinders and also I noticed going up the main mast the hard body line going to the dipper was hit at one time and it was crimped so badly it was almost shut off oil flow letting in very little hyd fluid so I replaced it with a new one which to my shook new Holland had in stock . . I bought this to do a very big job maybe a 3 week job for a friend of the family and another weeks work at my brothers house pulling the tree stumps too. But as soon as it hits a tree root it stops. I even took off the small 20"bucket and made a root ripper knife blade with very sharp teeth and it too will not rip the roots. To hear 160 degrees I not over heating is good news. Although weak the first time I worked it really good for around an hour near the end I noticed the backhoe bucket started leaking and yes it did go to 200 degrees or slightly higher on the hydraulic temperature. I am bad to run a backhoe at lower RPM's around 1500 to save fuel and I read in the book to keep it cool it must run at higher RPM's. I did not do any pressure testing as yet or relief valve testing I don't have those gages. But I guess I need to make some up or buy them. I'm feeling out of my circle of knowledge and confort zone, but love hyd too

J_J · May 19, 2014

Re: New Holland 555 E Hyd oil over heating where is relief valve? & regeneration chec

About $30 Hyd test set.

http://www.tractorbynet.com/forums/...do-these-symptoms-tell-3000-psi-hyd-test-gage

http://www.tractorbynet.com/forums/...do-these-symptoms-tell-3000-psi-hyd-test-gage

bruce0777 · Jun 8, 2014

Re: New Holland 555 E Hyd oil over heating where is relief valve? & regeneration chec

Up date for what I was able to do so far, I bought the gages and adaptor connectors. I put the gage on the main boom lift cylinder. The hyd manual said the pressure should be set to 4600 PSI . When I first tested this it was at 2500 PSI. So I found the control valve located just in front of the hyd pump. I screwed it in one complete turn and now the pressure was 3500 PSI on gage. I ran it like this to test it out and the hyd temp now went down from 180 degrees to 160 degrees. After working it for hours I turned the screw in one more half turn and it now ran with a hyd temp of 140 degrees . Am I right to try to go to 4600 PSI as the manual says for the main boom pressure? It seems as though the backhoe section is shy of having all it's muscle . It has a lot of the original hyd hoses and I have replaced half of them already. Since I turned up the pressure I blew two old hoses.

J_J · Jun 8, 2014

Re: New Holland 555 E Hyd oil over heating where is relief valve? & regeneration chec

What model loader and BH do you have on the 555 E?

4600 psi seems high.

Every hyd circuit might not use that high pressure and therefore the relief valve for each circuit could be different.