Volvo D4.260 steering issue

[Nigbb]

Hi, looking for some suggestions on this please.
When out I noticed that the boat kept creeping to port and needed constant correction, but would go to stb with no problem when the helm was turned so got back to the marina with no real problem. Now the drives are hard to port and will not move under engine power or by the helm pump with no engine running.
Someone suggested flushing the system and refresh the fluid which I have done but no change.
With or without the engine running there is no resistance to stb but its up against the stops so to speak when turned to port.
Does this sound like an issue with the helm pump? Do they give trouble?
Any suggestions would be welcome.
Cheers Nigel

 

[ChromeDome]

Engines and drives make & model?
Servo assisted?

 

[julians]

Hi, looking for some suggestions on this please.
When out I noticed that the boat kept creeping to port and needed constant correction, but would go to stb with no problem when the helm was turned so got back to the marina with no real problem. Now the drives are hard to port and will not move under engine power or by the helm pump with no engine running.
Someone suggested flushing the system and refresh the fluid which I have done but no change.
With or without the engine running there is no resistance to stb but its up against the stops so to speak when turned to port.
Does this sound like an issue with the helm pump? Do they give trouble?
Any suggestions would be welcome.
Cheers Nigel

Check the fluid level at the steering wheel end. There is a little screw cap just above the steering wheel,unscrew and see if there is fluid in there,from memory i think it needs to be 10mmbelow the cap,but check the manual for certainty

If this is low/empty then your steering rams seals have probably failed - common issue, this causes a lot of your steering fluid to be pumped out into the sea. You can probably get away with just adding more fluid at the steering wheel as a get you home fix until you can get the rams replaced

I know you said you had replaced the fluid,but if you did this using the reservoir in the engine room you won't have purged all the air out of the system, you need to add fluid from the steering wheel top up point,and keep rotating the wheel to purge the air

 

[Nigbb]

Thanks for that reply, I did completely (or pretty much)drain the system, the reservoir, the helm pump and even took low pressure return pip off the engine pump, I then refilled with new fluid and drained again so pretty sure I have good new fluid everywhere now.
After chasing the air out and filling the helm pump as well as the reservoir I do now have steering when the engines are running.
But when no engine there is little resistance on the helm pump to stb and it won't turn the drives, however it will turn to port.
One more plot twist, I left the engine running with the drives centred and after 8-10 mins the drives had crept over to port by about 50%, does that ri g any bells to anyone?
Cheers Nigel

 

[ChromeDome]

If the engine alone turns the drives I'd be focusing on the servo pumps. By running engines individually it should be possible to find the culprit

 

[simonfraser]

Check the fluid level at the steering wheel end. There is a little screw cap just above the steering wheel,unscrew and see if there is fluid in there,from memory i think it needs to be 10mmbelow the cap,but check the manual for certainty

If this is low/empty then your steering rams seals have probably failed - common issue, this causes a lot of your steering fluid to be pumped out into the sea. You can probably get away with just adding more fluid at the steering wheel as a get you home fix until you can get the rams replaced

I know you said you had replaced the fluid,but if you did this using the reservoir in the engine room you won't have purged all the air out of the system, you need to add fluid from the steering wheel top up point,and keep rotating the wheel to purge the air

you can replace 'just' the seals after the rams have been cleaned up

 

[Nigbb]

Engines and drives make & model?
Servo assisted?

D4.260 with DPH-A drives, they have one hydraulic ram for each drive

 

[Nigbb]

If the engine alone turns the drives I'd be focusing on the servo pumps. By running engines individually it should be possible to find the culprit

Only the stb engine has the power steering pump, what do you mean by servo pump, that sounds like something I don't know about.

 

[Nigbb]

you can replace 'just' the seals after the rams have been cleaned up

We don't have any rainbows in the water si I am convinced the rams are not leaking

 

[ChromeDome]

Only the stb engine has the power steering pump, what do you mean by servo pump, that sounds like something I don't know about.

Power steering = servo so same thing

 

[spannerman]

On a D4 double installation there has to be an interconnect between the drives so they both move together, this can be with an external metal tiebar, or what volvo call a hydraulic tiebar where the fluid goes to the rams one one drive then over to the other and back to the helm pump. If you have this system it could need bleeding at the valve block which is usually on the transom between the engines, it needs a special bleed kit which dealers have as its impossible without it as you bleed 3 lines at once. If there is air in this valve or its faulty it can stop the drives from centering. I once spent hours fixing this on a Princess V45. If you have the external tiebar then you have a simpler system which still has a shuttle valve which is operated by the low pressure from the helm pump and allows high pressure from the servo pump to operate the relevant ram, it should self centre with no input from the wheel meaning the pressure is equalised and the rams stay in what ever position they are in. This valve can partially seize if there has been water ingress from a faulty ram or hose, the give away is pink oil in the reservoir on the engine instead of clear red, this will allow high pressure oil to one side of the system causing creep as you have described.

 

[Nigbb]

Aha, that is starting to ring true, I do have the solid bar tying the drives together and when I purged the system and flushed it the fluid was indeed pink. Do you think the fact that I have very little resistance on the helm going to stb and good resistance going to port could be a fault in the helm pump? Have you ever had these give trouble? I wondered if that pressure is too low to activate the shuttle valve?

 

[spannerman]

Helm pumps rarely give any trouble apart from leaks from the shaft seals, it sounds more like the shuttle valve is stiff from corrosion and not floating back to its neutral position. If its slightly off centre at rest it will admit high pressure from the servo pump to one side of the sytem. I would start with that, its usually at the back of the engine, just follow the hoses and it should have 4 hoses, two from the helm and one from the servo pump and a return to the reservoir.

 

[Nigbb]

OK thanks ,I will take a look at that.
Cheers Nigel

 

[Nigbb]

UPDATE. Problem solved.
I finally had the VP agents in Chichester to take a look and as I suspected the problem was in the helm pump.
A quick easy fix, 1.5 hrs labour charge and I am all good.
Thanks to everyone for their input.
Cheers Nigel

 

[spannerman]

Great news it was a relatively easy and cheap fix.