How are you feeding your ps pump?

patooyee · Nov 18, 2012

I'm having cavitation issues feeding my pumps. They are both remote reservoir using PSC reservoirs, -12 inlet. I've got the intake tubes as short and straight as possible. One of them is only about 10" long with a straight fitting on both ends yet the pump still cavitates. (New pumps) I can use regulated air and pressurize the reservoirs to 15 psi and the problem goes away, thus my thinking there is restriction in the inlets but I've got the hoses routed so straight and close to the pumps that there is almost no way possible to make them any more ideal. I'm starting to think that the PSC reservoirs may actually have a restriction in them.

So you guys who don't have PS issues, please describe how the pump actually receives fluid from the resi on your setup.

civicmindedex79 · Nov 18, 2012

Mine is a PSC resi/filter combo -10an line runs from bottom of windsheild bars across injector rail and into PSC pump. Not any issues that I can tell so far.

John Galbreath Jr. · Nov 18, 2012

Look here:

http://www.pscmotorsports.com/pdf/tech/reservoir_tips.pdf

and

http://www.pscmotorsports.com/pdf/tech/bleeding.pdf

And is your line from the PSC reservoir to the PS pump SUCTION rated? Some will collapse uder high fluid movement if not suction rated.

patooyee · Nov 18, 2012

Yes, definitely made sure I used suction rated line. Thanks for links.

And the system bleeds fine, no foam, bubbles, or froth in the reservoirs at all, fluid levels don't change at all from running to not running.

draggbody · Nov 18, 2012

i run a psc res to a stock pump housing with all of the holes welded up and a howe pump... about 3 different fittings screwed to each other just to route it to a -10 line with a pretty sizeable kink in it, works great... i think you often times over think ****, no need for ultra bling, spec sheet recommended parts, just leave it alone and try a trail fix... my buggy holds up pretty well with a life of neglect, poor maintenance and trail fixes...

patooyee · Nov 18, 2012

I experiment with stuff, especially steering, and this current setup is the worst I have had to date. It is so bad that I know there is something wrong. If you've got basically open exhaust and at 5000 rpm you can't hear the engine over the pumps, they're not working properly.

I'll be the first to admit that I do overthink stuff sometimes, but definitely not in this case. Mark has been there, heard it, and agrees.

I'm stumped this time because I've got nearly text-book plumbing going on with one of the pumps yet still having issues.

Elliott · Nov 18, 2012

Could it be your out go side restricting your flow?

patooyee · Nov 18, 2012

Elliott said:
Could it be your out go side restricting your flow?

I have considered that but, to be honest, don't know exactly how it would affect it. My pressure lines are -6 and my returns are -8. According to every hydraulics spec sheet, manual, guide, and expert I have spoken to (And it has been many.) those should be more than adequate for my flow.

John Galbreath Jr. · Nov 18, 2012

patooyee said:
no foam, bubbles, or froth in the reservoirs at all, fluid levels don't change at all from running to not running.

Then, based on that, I say you are not running the pump dry. That gives you the strawberry milkshake look in the reservoir. Call Lance at PSC and pick his brain, he is good at it.

You say new pumps, are they PSC? Are you sure you have the correct pump for your application?

patooyee · Nov 18, 2012

They're just stock TC pumps as would be found on a 2004 Grand Cherokee V8 w/hydraulic cooling fan. What is the correct application for a buggy?

I have an email in to Lance and will call him tomorrow when they are open.

Elliott · Nov 18, 2012

Wonder if it could be a pulley size problem? And that's the same size lines mine has, all tho im running krc's so I'm not real sure about your pumps?I just had to get the bigger flow valves for mine because the steering took more effort than what I thought, but it wasn't making any noise. Kinda sounds odd for it to be that loud and not milk the fluid.

patooyee · Nov 18, 2012

Elliott said:
Wonder if it could be a pulley size problem? And that's the same size lines mine has, all tho im running krc's so I'm not real sure about your pumps?I just had to get the bigger flow valves for mine because the steering took more effort than what I thought, but it wasn't making any noise. Kinda sounds odd for it to be that loud and not milk the fluid.

I've got LOTS of experience with air in systems. This noise is different and I am 100% confident its not air. Air will make a pump whine. The noise I am hearing is more like a melodic buzz saw. This is kind of the fun of experimenting to me. Once you hear both and can differentiate between them it helps you troubleshoot in the future. I know how to fix a whine. But I've never heard this buzz before which is why I am stuck.

I guess air in the system will cause cavitation, but cavitation can also occur without air in the system when output simply exceeds input. I guess this is the sound it makes in the case of the latter and it is very unique and distinctive now that I've heard both.

I'm using the stock OEM pulleys for the pump, but just to further experiment did try a slightly larger one to slow one of them pumps down and it didn't help.

The stock application used a 1/2" pressure line, which is equivalent to -8. So I know that my pressure line is smaller than stock but I also know the pump's output is far less than other applications that use -6 with no issues, so I feel like it should be OK. Plus, changing out all my pressure lines is a major ordeal that I will reserve as a last resort.

patooyee · Nov 18, 2012

Elliott said:
Wonder if it could be a pulley size problem? And that's the same size lines mine has, all tho im running krc's so I'm not real sure about your pumps?I just had to get the bigger flow valves for mine because the steering took more effort than what I thought, but it wasn't making any noise. Kinda sounds odd for it to be that loud and not milk the fluid.

What KRC pumps are you running and on what engine?

Elliott · Nov 18, 2012

The cast iron in jegs. They came with 2.5 gpm valves for roundy round cars but I got the 3.7 valves to go in it as soon as I get a second.Krc recommended 10 supply with 6 pressures so it sounds like you have all that right. I ended up using one reservoir and welding in an extra set of bungs for supply and return for the rear steer and the one reservoir feeds both my pumps fine but that's with double ended rams.

patooyee · Nov 18, 2012

Elliott said:
The cast iron in jegs. They came with 2.5 gpm valves for roundy round cars but I got the 3.7 valves to go in it as soon as I get a second.Krc recommended 10 supply with 6 pressures so it sounds like you have all that right. I ended up using one reservoir and welding in an extra set of bungs for supply and return for the rear steer and the one reservoir feeds both my pumps fine but that's with double ended rams.

Thanks, which engine? And what size pulleys?

Elliott · Nov 18, 2012

355. With stock size on both

Elliott · Nov 18, 2012

What size orbital and rams are you running?

patooyee · Nov 18, 2012

Elliott said:
What size orbital and rams are you running?

2.5" rams but this is happening when I'm not even turning the ram, just sitting in one spot running.

Not sure on my orbital. It was supplied by one of the aftermarket companies that was kind enough to remove all identification markings from it before shipping.

Here's some good tech:

http://www.krcpower.com/pdfs/KRC_Hose_Tech.pdf
http://www.krcpower.com/pdfs/KRC_Cast_Tech.pdf

The first one has a good point. I haven't checked my hydraulic fittings for the intake to make sure they actually have 3/4" holes in them. While they are -12 the holes may actually be smaller. That is one thing I will definitely check ASAP.

TBItoy · Nov 18, 2012

Yeah I'd check the orbital, especially since you don't know what the hell it is!

You may have a CLOSED CENTER orbital that is making the pumps stay in the the pressure bypass all the time.

That will make it sound like hell, but not foam the fluid. and just maybe the 15 PSI positve pressure is causing enough flow into the pump cavitiy/pressure relief that it is making it quieter?

A buddy of mine made that mistake one time (closed center valve), it sounded EXACTLY like what you are describing, and that was with a ham can P pump, so you know it wasn't cavitating.

ranger11 · Nov 18, 2012

Re: Re: How are you feeding your ps pump?

I had a similar problem on mine. Everything was new. I cracked open the supply line on the pump while running and it fixed my problem. I put 2 new pumps on and it don't the same thing. No air was in lines and steering worked pump was super loud.