Hydraulic Problems

[smwwoody]

I am having hydraulic issues with my Prentic 325 loader.  It will only swing at about 3/4 speed.  unless the main boom is all the way up until it wont go any higher and you hold back on the stick to keep trying to raise the main boom.  as long as you hold the stick back to raise the main boom it swings fine.  as soon as you release the stick the swing will slow down and not go back to full speed until you pull back on the main boom up stick.  the pressures at both pumps are good.

Please help

Thanks
Woody

[treeslayer2003]

IDK yer machine, does it have gear pumps?

[smwwoody]

yea gear pumps
swing motor is a piston motor

[treeslayer2003]

hmmm, i was thinking you may have variable pumps............thats kinda wierd then.
maybe theres a proportioning valve of some type on the fritz?
i'm just stabbing in the dark here.

[smwwoody]

not 100% sure on the pumps  how do i tell what type they are

[treeslayer2003]

good ?, maybe post a pic n some one here can prolly tell. i'm not the best on hydraulics but i woudn't give up.

i know they look different but i couldn't tell you how to tell.

[smwwoody]

I think it might be something sticking in the valve body, but I dont want to tear into it blindly.  the end cap gaskets for it are $190.00 each and need to be special ordered.  the whole valve body takes 10 of those gaskets

[Southside]

Hi Woody,

I had a similar problem with my 490, at first I thought it was a pilot valve sticking, tore all those off and did not find any problems.  In the end it was an "ice cube" relay that had gone bad which allowed the flow from both pumps to combine flow to the swing motor.  Both of my pumps tested good also, so it was not a pressure issue but a volume problem, I don't know how one would test that.  Not sure if that helps. 

BTW, how you been?

[smwwoody]

Southside
If you still have my number give me a call. I am wireing lights on one of my trucks right now and have some time to talk

Woody

[kiko]

Smwoody,  most  likely the poppet and seat is beat out on the swing valve causing a lose of load sense to the pumps , you are putting the pumps on full stroke with the boom effectively tricking the swing.  The seat and poppers are located under the end caps where pilot lines hook to control valve. Do you have a parts book?

[Southside]

Hi Woody,

I was in for a bite to eat when I sent that earlier, then went back out and worked on my trailer in between rain events, just catching up now, will give you a call Sunday

Jim

[smwwoody]

Kiko,

I havent been able to find a parts manual for it.  they are easy to find for the ones that had the Kawasaki Hydraulics,  but mine is one with the Vickers hydraulics.  The cat dealer told me that it was not available.

Does it sound to you like the problem is in the swing valve?  If so I will tear down the swing section monday and look for problems.

Thanks

Woody

[kiko]

It is vickers cmx valve.  Check out vicker.sh.cn/pdfs/m2413s.pdf   Page 6 pilot relief valve.  This is where the seat and poppet is located I spoke of.  There is one on each side of control valve. The poppet can be removed without removing end cap but the seat cannot.  Be carefully if removing end cap on bottom as main spool can slide out and then the oil is going come gushing.  It has been many moons since I worked on a 325 but in recollection the problem is likely with this seat and poppet being beat out, however it is probably not in the swing section but rather in the section next to and up stream to swing section.  My experience is only with the trailer mounted 325 so I am unaware of how the track valuing is set up.  So looking at the valve facing the turntable bearing, a bad pilot poppet would affect all the section to the right of the bad poppet and seat.  From left to right what is the order of the stack valves and where is the swing valve in relation to the main boom valve?  The gasket under the end cap is metal and can usually be reused.

[smwwoody]

Kiko

This is a trailer mounted 325.  I think the next section up stream from the swing valve is the main boom.  I tried to pull the main spool out of the swing valve but it would not move.  i tried bumping it with a plastic dead blow but i did not want to break anything.

The swing valve is on the far right end of the stack.  it is the last one in the flow

[kiko]

It seems that if the swing spool was not moving it never would reach full speed even while activating main boom, odd it would not come out.  Seriously , check the poppet seat on main boom section,  the end of the poppet should be perfectly conical, any damage to this will cause a down flow problem.  In general load sense diagnostics it is usually the function that tricks the load sense on where the leak is occurring . 

[smwwoody]

Kiko

Thanks for all your help.  I will look at the popets and seats in the morning and let you know what i found out

[1270d]

I have had a very similar problem with a harvester.  Just like kiko said, it was a load sense valve.

[smwwoody]

I checked and cleaned all the popets and seats. They all looked good. Problem still there

[smwwoody]

Problem just got worse. It all not swing at all now

[treeslayer2003]

if you had a gear motor on the swing, i would suspect it................curios to see what it is. wish i could help ya.

[smwwoody]

heading for South Carolina tomorrow to pick up a good used complete valve body.  I hope that fixes it I cant afford to be down any longer.  Once i get it fixed it is time to go loader shopping 

[kiko]

Sounds like you are back to that stuck spool.

[smwwoody]

Put the use valve body in yesterday and it runs better than ever. Now to sell the 325 and upgrade

[treeslayer2003]

well shoot.....its fixed now lol. glad ya got it fixed.

[smwwoody]

The used valve body lasted about 3 hours before it started giving me a lot of problems.  Looks like i will be loader shopping in the morning................