VP DPH steering shuttle valve access

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nickcami

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Hi. I have an Elan 35 power boat with VP D4 225 engines with DPH Z-drives. I had the usual leaky steering cylinder problems and associated water ingress into the hydraulic steering system, which we fixed by replacing the rams and replacing the ATF. However I ended up with a problem wherein the boat steering would drift to port on its own while engines were running.

We took the helm pump apart and cleaned it, re-bled the system but the problem persisted. We also noted that while the helm wheel goes very stiff when hard over to starboard, it will continue to turn when hard over to port.

After reading through this great forum, it seems that the only component still to check is the shuttle valve unit on the stbd transom guard, but this is sandwiched between the engine and transom, completely inaccessible. Has anyone had this problem? And can anyone guide me as to whether the rear of the D4-225 can be dismantled to enable access to the valve?

Any help much appreciated!

thks
Nick
 
I'm sure Volvopaul or Spannerman will be along soon and answer properly; however from what I've read and the symptoms you've put donw, I think you're right to suspect the shuttlevalve is in trouble....
 
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nickcami said:
We took the helm pump apart and cleaned it, re-bled the system but the problem persisted. We also noted that while the helm wheel goes very stiff when hard over to starboard, it will continue to turn when hard over to port.Nick
Click to expand...

I wouldn't mind betting you still have air in the system. Had this problem myself.

Suggest you remove & test the lock-valve ?
 
Hi Sandyman, thanks for your suggestion. Which is the lock-valve?

So far we have stripped and reassembled the helm station and re-bled the system several times. Other than the helm, the only valve left to check is the shuttle-valve at the back of the stbd engine. This is seemingly impossible to remove without removing the engine. I am hoping that some guru on here has found a way of getting to it without dismantling half the damn boat!
 
It has also been suggested to me that before trying to physically access the shuttle-valve, that we flush it out with some sort of special cleaning fluid to clear any possible dirt that may be causing the leaking. Does anyone have any ideas on this and/or suggestions as to what cleaning fluid to use??

Many thanks
Nick
 
Never had any success working on the shuttle valve with the engine in siti, can only suggest that you remove the drive and mounting ring on the outside of the transom, then remove the engine mount to hull bolts and exhaust bend and then slide the engine forward if you have space, its a lot easier tham disconnecting absolutely everything.
you will need to support the rear of the engine with a hoist, or if there is no access we slide a scaffold pole with half of a U/J coupling welded to it on to the splined output shaft and slide it into the boat with the engine so the rear of the engine can't drop down.
This should give you enough room, we use this method to replace exhaust down pipes.
 
FFS....what on earth are boat builders up to.... all this grief just to get at a bit of kit that is going to need looking at sooner or later.:(
 
spannerman said:
Never had any success working on the shuttle valve with the engine in siti, can only suggest that you remove the drive and mounting ring on the outside of the transom, then remove the engine mount to hull bolts and exhaust bend and then slide the engine forward if you have space, its a lot easier tham disconnecting absolutely everything.
you will need to support the rear of the engine with a hoist, or if there is no access we slide a scaffold pole with half of a U/J coupling welded to it on to the splined output shaft and slide it into the boat with the engine so the rear of the engine can't drop down.
This should give you enough room, we use this method to replace exhaust down pipes.
Click to expand...

Thanks Spannerman - I guess this is the only way then... :eek: Do you think it is worth trying to flush the valve with solvent first? If so, what would you suggest? thanks Nick
 
nickcami said:
Hi Sandyman, thanks for your suggestion. Which is the lock-valve?
Click to expand...

Not to sure on your system, but to me the lock valve is situated inside or on the rear of the helm pump. Basically it is a small double ended piston with a spring either side and it opens & closes ports such that hydraulic pressure is only applied to the system in the direction you wish to travel.
Your steering problems are exactly what I experienced and eventually found that one of the ports was not closing properly due to wear on one end of the piston.

How do you bleed your system ?

Hope that helps.
 
Sandyman said:
Your steering problems are exactly what I experienced and eventually found that one of the ports was not closing properly due to wear on one end of the piston.

How do you bleed your system ?

Hope that helps.
Click to expand...

How did you establish that one of the ports on the helm was not closing properly?!? I am being assured by VP that the helm pump has been dismantled and checked, and that the only bit of kit not yet checked is the shuttle-valve. Yet I am not convinced that we have established conclusively that the helm pump is fine simply by removing the internal valves and visually inspecting them. Did you perform a pressure test to establish where the leak was? If not, how did you do it?
thanks, Nick
 
Don't think my previous ideas will be of much help to you.

Hum........pity there is not an expanded view of the pump itself.

Obviously quite an old bit of kit. Sounds like a wear & tear type of problem.

How do you add fluid when bleeding? Is it through the vent on top of the pump ?
 
Sandyman said:
How do you add fluid when bleeding? Is it through the vent on top of the pump ?
Click to expand...

One can add oil via the vent at the top of the pump and also by connecting up a header tank to the main low-pressure oil circuit in the engine bay (the lines leading to each ram)....

Visual inspection of the helm pump valves showed nothing out of the ordinary :(

One way to test it would be to conclusively eliminate the helm pump from the circuit and see if the drive legs still go hard-over when the engines are started. Any ideas as to how best to do this?
 
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