p4-33

Hello all,

Just got the motors back in the ol' gal, life is good.

Having problems with my power steering pumps and reservoir level. I've got twin P/S pumps, single P/S fluid reservoir, full hydraulics to the helm. When I run the stbd motor by itself, steering is smooth, res level stays put, even when cranking the wheel around. If I run the port motor by itself, the res level climbs to the point of overflowing, and the P/S pump whines like it's starving for fluid, wheel turns harder. Running both motors, everything is fine, res level stays even, steers like butter, no whining.

This system worked fine last season with no problems. I'm going to try swapping P/S pumps between motors tomorrow, but I can't see how a bad pump would cause this. The only changes to the P/S system was adding quick-disconnects to all of the hydraulic lines, and all new plumbing parts are identical on both motors. At least this should make swapping pumps less messy.

Ideas anyone?

Thanks,
Brian

p4-33

P.S. None of the steering ram lines were touched, just the lines on and to the motors.

p4-33

One more try...

p4-33

I swapped the P/S pumps, checked all of the lines for bends/kinks, and the problem remains with the port motor.

Going to try to bleed it tonight. Any other ideas to look for?

Thanks,
Brian

BenPerfected

Why use two pumps? One pump will work well and there is less pumbing. What does Latham think?

p4-33

Two pumps for redundancy - loose a belt, P/S pump, etc, still have full control. Latham sells dual-pump systems as a fairly common option.

Haven't talked to Latham yet, that's the next step. I bled the entire systems at the rams, and still same results. If they don't have any ideas, I'll give XS Performance a shot. There's been some pretty good words said about these guys lately.

I think there may be a clog in the HP line coming off the port pump, or maybe an obstruction in the Y-block. Every other line in the system is working fine, so there's only a couple of places where something could be blocked. Don't know much about what's in the Y-block, as there's a couple of knob-nut looking things on top of it. Kinda looks like adjustment valves, but losening them just makes fluid piss out. I'll dissect it tonight and see.

Thanks,
Brian

Falcon

Do you have a common reservoir plumbed to the tops of both engine/pump reservoirs or just one reservoir with lines to both pumps? When I say pumps, are they the older automotive style pumps with the metal reservoir around the actual pump? What I am trying to get at is, does the return oil split and return to the pumps or pump reservoirs first or does the return line from the helm go right through the coolers to the main reservoir?

Depending on your setup, there are a couple of possibilities. If you have only one reservoir with the return lines going right from the coolers to it, how long and how large are the lines going to the pumps. The pumps need a very good, low line loss supply. They don't like to be starved.

If you have metal can style pumps and the return line from the helm is split to return to both pumps/reservoirs, you might have too much restriction in the line returning to the pump that whines or you might have an air bubble in that individual reservoir for the pump. You can just loosen the cap on the pump/reservoir, letting the oil from the main reservoir fill the pump/reservoir while letting the air out. Air returned to the pump/reservoir doesn't always get burbed out into the main reservoir. It also doesn't like to pass through the oil in the line in the typically small line used between the pump/reservoir and the main reservoir.

You mentioned quick disconnects. Most quick disconnects are not designed for high flow rates with little pressure drop. This is very important on the return part of the circuit. Also, you should use #8 lines from the output of the pump "check valve block" to the helm and also on the return from the helm to the split to the 2 coolers. This is because you have twice the flow rate to the helm with both pumps running. Excess pressure in the recirculating "pump circuit", as I like to call it, costs hp by making the pump work harder and also increases the chance of starving the helm of oil at idle, especially when only 1 pump is supplying that oil. When the helm doesn't have enough oil supplied for it's turning rate it goes into manual steering mode.

Well that was a long winded description. Let us know what you find.

p4-33

Thanks for the reply Falcon,

I have a single reservoir that feeds caps on both pumps. Res feeds one cap, and flows through to the other. "Problem child" motor is farthest from res. These are std HP500 P/S pumps, automotive style as I think you're describing.

From the pressure side of the pumps, I have #6 lines that go to a Latham y-block, with a #6 quick-disconnect in between. AN8 fitting and #8 line comes out of the y-block. From there, goes up thru the helm and returns back to a tee fitting, AN8 on input side of tee, 3/8" hose barbs on both outputs. These 3/8" lines feed my P/S coolers, and return back to the P/S pumps. Both inputs and outputs of the coolers have 3/8" quick disconnects, for removing the pumps, or pulling the motors, depending where I need to disconnect. That's the whole plumbing picture, at least on the pressure circuit.

The thing that kicks my a$$ is I swapped pumps between the motors, and the problem stayed with one motor. If I had a pump that needed burped, or a bad pump, the problem should have moved to the other motor. Same plumbing hardware (quick-disconnects and all) on both motors, and one side works fine. It also all worked flawlessly last season, only changes are the disconnects.

I just pulled off the y-block and looked inside, nothing seemed blocked there. What are the two valve-looking knobs on the top of this thing for? Is there a pressure balance adjustment there?

While the pressure side was disconnected, I cranked over the motor, and a LARGE amount of fluid blew out. Just for practice, I did it to the good side, too. Both pumps appear to be flowing well. An hour later after cleaning up the mess, I reassembled, and tried it again. Same chit.

I hear ya on the disconnect restriction. I'd like to not agree, but I'm to the point where I need to start backing out some of the changes. I have enough spare line to bypass the return line disconnects. Pressure side would involve a trip to the hydraulic shop. I'm also thinking I might have a clog in my P/S cooler. F'in thing is between the motors, though. Kinda tight in there.

I really appreciate the help. If anything else comes to mind, I'm all ears.

Thanks again,
Brian

Falcon

I believe the problem is on the return side. Remember that half, or more, of the oil is being returned to the cooler/pump that is not running. This oil has to go through the cap and through the line back to the furthest pump. Typically the caps/fittings/line size on the caps are marginal to handle pump flow. So instead of flowing back to the pump that is running it goes into the main reservoir because it doesn't have as much restriction. To make things a little worse, the cooler/line routing on the suspect side may be a little more restrictive than the good side. I would try upsizing and taking out as much restriction on the caps/main reservoir line as possible. Also repeat the filling of the pump reservoirs by loosening the caps one at a time and letting oil run down the line from the main reservoir to top off the pump reservoirs.

Good luck!

p4-33

Problem solved!

Turns out that I wasn't feeding the tops of the pumps with enough volume of fluid. The closest pump to the main reservoir was getting a decent supply, but the farthest pump was starving for fluid, aerating the fluid, and backing up the supply line. By moving the reservoir supply line directly to the problem side, this confirmed it to work correctly. See, these quick disconnects do come in handy.

With both motors running, the Priority Valve (y-block) sensed one side had low pressure and directed pressure to the helm from the good side. And to answer my earlier question, there is no adjustment here, it's engineered to operate with spring pressure inside the valves.

This problem all stems from the new hoses and quick disconnects from the reservoir supply lines to the pump caps. They are 5/16" lines and fittings. Enough supply capacity for one pump, not two. To fix, just need to bump up hose sizes and disconnects a notch to 3/8", and should be good to go!

All other disconnects are still in place.

Thanks for the help! And thanks Ted Chance at Latham for pointing me in the right direction. Thank you, too, Falcon.

Brian