How to test hydraulic pressure

J_J · May 20, 2009

Your divider may not be dividing. Does your divider valve divide the fluid so some or most, or just how is it configured. One leg off the output may service the power steering, and the other leg may go to the loader valve. Does the power steering work better/faster than it was before. Some divider valves are equal in the output. Say you had 10 GPM going to the divider, then, 5 GPM would exit out each port of the valve. Some of them are unequal, in that one leg may only feed 3 GPM, and the other leg push out 7 GPM. Tee your gage in before the divider valve, and tell us the pressure. I am assuming that the fluid comes directly from the pump to the divider valve, and I believe you said it had a relief. There are several ways to trouble shoot systems, and that is to work from known good points, through to the stop point. The other way is to work backward to find the first good point.

SPYDERLK · May 20, 2009

kennyd said:
JJ,
I do not agree that deadheading the system is bad for a few seconds at a time-it happens quite frequently while using any function normally. That is the only way to test the PRV and see if the pump is reaching proper pressure. Sure, you can add T's all over the system to plug a gauge into...but you still need to deadhead the system to test it properly.

That is not a deadhead if there is a functioning relief valve in the pressure circuit. If you dont have the relief you do have a deadhead. It will cause something to break instantly. The fluid must have a place to go or pressure immediately rises to failure.
larry

DIXIEDOG · May 20, 2009

J_J said:
Your divider may not be dividing. Does your divider valve divide the fluid so some or most, or just how is it configured. One leg off the output may service the power steering, and the other leg may go to the loader valve. Does the power steering work better/faster than it was before. Some divider valves are equal in the output. Say you had 10 GPM going to the divider, then, 5 GPM would exit out each port of the valve. Some of them are unequal, in that one leg may only feed 3 GPM, and the other leg push out 7 GPM. Tee your gage in before the divider valve, and tell us the pressure. I am assuming that the fluid comes directly from the pump to the divider valve, and I believe you said it had a relief. There are several ways to trouble shoot systems, and that is to work from known good points, through to the stop point. The other way is to work backward to find the first good point.

On my tractor the fluid goes direct from the pump to a divider valve. The pump is a 17 GPM pump and 3.5 is supposed to be dedicated to the power steering and the rest is supposed to go to my aux. line which runs to a rear divider block. My power steering didn't get any faster, I will need to pick up a T to hook up to my lines, right now I've only got the gauge and a bunch of thread adapters but not T. After I get the T and test the pressures I will post my results. Thanks for the help guys, I've done a lot of engine work over the years but I have no hydraulic experience....yet

kennyd · May 21, 2009

J_J said:
Kenny,

You, I, and a lot of others know this, but I think we are trying to help someone not quite familiar with hydraulics. If he damages something, he might just blame us for his lack of knowledge, and I was trying to avoid that. Instead of that groan/whine, when the relief kicks in, you might hear a pop, and fluid is all over the ground..

Agreed. That is why I specified "just be sure to only deadhead the system for a few seconds at a time."

kennyd · May 21, 2009

SPYDERLK said:
That is not a deadhead if there is a functioning relief valve in the pressure circuit. If you dont have the relief you do have a deadhead. It will cause something to break instantly. The fluid must have a place to go or pressure immediately rises to failure.
larry

While "technically" you are correct...this is a accepted term used in the testing of a PRV. It's even mentioned in my service manual.

DIXIEDOG · Jun 14, 2009

Just an update. I was finally able to get all the fittings to test my hydraulic pressure and I had under 200lbs of pressure

Although my relief valve didn't look to be stuck open it must have been. I changed the relief valve and all is well for now

On a side note I think I got the world's oldest remaining new relief valve, it was still in an original International box

They had it so long that it wasn't in their computer system because they had it before they got the computers. Price was still the same $220 but at least my front end loader is working again

Thanks for the help guys, now I've gotta go finish moving my rocks

J_J · Jun 14, 2009

You paid how much for a relief valve? Can you post a picture, and perhaps a part number.

Is this similar to what you purchased, and installed, or did you purchase the divider block assembly with relief valve.

https://www.surpluscenter.com/item.asp?UID=2009061420490339&item=9-4351&catname=hydraulic

DIXIEDOG · Jun 15, 2009

It was this one. The one you linked was only 600 psi, mine is 1600psi. It was only the relief valve, no divider block. I wish parts for this were cheaper but I haven't found any cheaper ones yet

Case/IH part# 389033R92

J_J · Jun 15, 2009

DIXIEDOG said:
It was this one. The one you linked was only 600 psi, mine is 1600psi. It was only the relief valve, no divider block. I wish parts for this were cheaper but I haven't found any cheaper ones yet

Case/IH part# 389033R92

I just showed that picture for the style of relief valve. I knew your valve had a higher pressure. I don't know if you have to use a Case relief valve. It should cross to something else. Maybe Wayne can answer that one. about substitution.