Hydraulic issue

[Fvdestiny]

I have 38 nb with a steering issue that has gone unresolved. The system has a 12 gallon tank that (I just installed site glass )with a filter on the return and (also installed 2 ball valves on both lines running from tank for shut offs),that feeds a Crowe v10 vane pump transmission driven that is approx 5-6 ft away and approx 2 ft below tank (so flow from tank is definitely down hill). The pump then flows to a (shafer filter that was installed by previous owner, )then to a 2000 psi pressure gauge newly installed .then to the auto pilot solenoid,which then feeds the main helm.from there the lines run to the 2nd helm in the cockpit then back to tank to complete the loop.
The steering has not worked consistently since I've had the boat.
We just took tank out to retrofit sight glass and add a fill that had easier access, cleaned the tank and reinstalled and filled leaving room for expansion. When steering works 100% the psi on the gauge will be 1000-1200 psi. The steering will then get really hard and pressure will drop to 200-400 psi.
?????? Is I've I've spoken to Hydroslave and they say it's very unusual to have ai pump go bad ,but this is the only thing that hasnt been changed.
Is it possible that relief valve in the pump could be getting hung up and causing this issue with steering? No other real explanation. The pumps range in price ,but dont want to spend $600-800 if it's not the pump. HELP

 

[Stinkpot]

FVDestiny:

You didn't mention a cooler in your hydraulic system flow path, is there one? When my boat was first launched, and after about four hours of running, I practically lost steering (of course when just approaching the dock). When I grabbed the helm behind the wheel it was hot as a pistol - the hydraulic tank was pretty hot too. Installed a small cooler in the system and all is well.

My $0.02.

 

[Fvdestiny]

Sorry there is a cooler that taps in to cool the helm.
Thanks for reply.

 

[traditions]

I would start with the relief valve.Does it make a sqreeching noise when you ho;d the helm hard over?It should as this is the relief valve bypassing pressure.Does the pump have a poppet type relief? I have seen these bad from new before.I have also seen broken springs in reliefs,but when thats the case you never get pressure.Had a similar stiuation once,turned out it was a plastic fitting plug that was in the tank.I would get rid of a filter mon the pressure side,the one in the return is sufficient.

 

[unclefish]

I would start with the relief valve deal. But I talked to Donnie champion in os and he had steering problems with his hh until the put the right cooler in there to. up north where they can probally get away with it water cold all year.down here water is warm and getting warmer by the day. Use a temp gun and check your tank and if you can get to cooler and see what is going in and coming out at-

 

[Pedlyr]

Maybe this can help.....Sorry, I am not familiar with your setup.

Is there a check valve in the system? Sometimes right out of the tank, but not usually. Or on a directional valve block. Where a solenoid may be. They usually are hex shaped and say 4 - 6 inches long. Maybe worth a look.

I have also seen steering systems where you can adjust the pressure thru a regulating block. Has a flush mounted lever on it.

I am going thru this same issue with a crane on a barge right now. I am going to take the directional valve apart next. Something is not letting the pressure "relief".

 

[traditions]

If you have 1200psi and it drops to 200 during use,the pressure is going some where.Either the pump is cavtating or the relief valve is dumping all the pressure back to the tank.There should be a flow controll on your seleniod valve,but that wouldnt explain the sudden drop in pressure.Hot oil could cause a drop,but I have seen steering systems real hot and still steer fine.The old canister systems with a gallon of oil used to run super hot when hooked to a high reving gas engine.What does the pump look like?Is it square on the back with three hoses ,b mount?

 

[Fvdestiny]

1st thank you all for your responses.I am going to pull the pump and order a new one. The relief valve must be getting hung up. the cooler really helps cool the system..If I forget to flip the cooler pump switch the helms get really hot..Anyway , I feel like I have improved everything I could with the tank etc..Process of elimination..thanks

 

[traditions]

What kind of cooler do you have?Its not a transmission type with sea water running thru it? Not hard to change relief on the boat.

 

[Super Suck]

Is the pump big enough?

 

[Fvdestiny]

Just pulled pump and sent out to have bench tested. Had a prio issue with relief valve getting hung up. Will know in a couple of days. Thanks