Luigi

Power steering not working

15 posts in this topic

Chaparral 204 2008 4.3 Gxi Volvo penta 

power steering stopped working suddenly. I changed the serpentine belt, changed out the fluid with Volvo trim/power steering fluid. 

What else should I look at? 

I tried turning wheel lock to lock with engine off and on. No change. 

Any imput would be helpful, I was told that these pumps last forever 

it does work intermittently, weird  

thank you 

 

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10 years old ?  Check for voltage RIGHT ON the pump motor terminals.  Could be the motor brushes are worn out.  Are they replaceable ? Does it ave a cap your fingers can twist counter clockwise to inspect the brushes ?

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12 minutes ago, cyclops2 said:

10 years old ?  Check for voltage RIGHT ON the pump motor terminals.  Could be the motor brushes are worn out.  Are they replaceable ? Does it ave a cap your fingers can twist counter clockwise to inspect the brushes ?

Didn’t know there was electric connected to the pump and I thought only powered by the serpentine belt. 

 

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  Was thinking power trim motor.  Sorry.

Power off. Can you push the drive left or right with a lot of effort ?  Have you found the pump oil gone & refilled ?

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When I push it I would say it’s medium to little effort. 

When engine running and it being off nothing changes on effort to turn wheel. I did flush the oil. Not sure if I maybe need to bleed the system. I searched around and saw that simple turning lock to lock would do the job. What should I check next?

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The belt driven pump is a positive displacement rotary vane design, and if the engine is running, the oil is in circulation to and from the steering ram, but is doing so at minimal pressure as there is no resistance to it's flow. When steering input is applied at the wheel, a diverter valve in the end of the ram moves a spool and diverts the flow to one end of the ram's internal piston or the other, while the exhausted oil from the other end of the ram is displaced back to the pump suction. This slip stream varies in volume depending upon how fast the steering wheel is being turned. When wheel movement stops, the spool returns to it's home position, and all of the pump's delivery is in simple low pressure circulation and is returned to the pump suction line. This all works sweet, until an operator turns the wheel all the way to either port or starboard. The diverter is telling the pump that it needs full flow to the ram, but the ram is at the end of it's limit of travel and pressure builds to excessive levels. At this point, an internal pressure relief valve opens and dumps the excess pressure back to the low pressure side preventing system damage. Some of these pressure relief valves are pump mounted but most are an integral part of the ram. In your case, either the diverter valve is sticking, or your safety valve hangs open on occasion. It would seem that the pump is working fine as you stated that the assist works on occasion. The bad news is that on the newer Volvo's the ram is serviced as an assembly, but you can tell if that is the case on yours by seeing if it is a sealed unit, or if the diverter valve is bolted on to the end of the ram assembly.  Good luck.   W

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On 10/13/2017 at 9:19 AM, Wingnut said:

The belt driven pump is a positive displacement rotary vane design, and if the engine is running, the oil is in circulation to and from the steering ram, but is doing so at minimal pressure as there is no resistance to it's flow. When steering input is applied at the wheel, a diverter valve in the end of the ram moves a spool and diverts the flow to one end of the ram's internal piston or the other, while the exhausted oil from the other end of the ram is displaced back to the pump suction. This slip stream varies in volume depending upon how fast the steering wheel is being turned. When wheel movement stops, the spool returns to it's home position, and all of the pump's delivery is in simple low pressure circulation and is returned to the pump suction line. This all works sweet, until an operator turns the wheel all the way to either port or starboard. The diverter is telling the pump that it needs full flow to the ram, but the ram is at the end of it's limit of travel and pressure builds to excessive levels. At this point, an internal pressure relief valve opens and dumps the excess pressure back to the low pressure side preventing system damage. Some of these pressure relief valves are pump mounted but most are an integral part of the ram. In your case, either the diverter valve is sticking, or your safety valve hangs open on occasion. It would seem that the pump is working fine as you stated that the assist works on occasion. The bad news is that on the newer Volvo's the ram is serviced as an assembly, but you can tell if that is the case on yours by seeing if it is a sealed unit, or if the diverter valve is bolted on to the end of the ram assembly.  Good luck.   W

Do you know why when I sometimes start the boat out of the water, the steering wheel turns by itself all the way to starboard side (Quick movement)  Doesn’t do that all the time. Sign that the pump is actually working?

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7 hours ago, Luigi said:

Do you know why when I sometimes start the boat out of the water, the steering wheel turns by itself all the way to starboard side (Quick movement)  Doesn’t do that all the time. Sign that the pump is actually working?

That is an indication that the spool valve is not finding it's null bias when at rest. Two counter-opposing springs are intended to auto center the valve, and keeping the oil flow in full by-pass back to the pump. Time to service the diverter.  W

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1 hour ago, Wingnut said:

That is an indication that the spool valve is not finding it's null bias when at rest. Two counter-opposing springs are intended to auto center the valve, and keeping the oil flow in full by-pass back to the pump. Time to service the diverter.  W

Do you have a diagram of where the diverter valve is located? All I can find is the steering ram with piston etc... sorry for my ignorance as the power steering is my weakness area. Could this be a DIY? It’s hard to get a Mechanic out here in Miami since this is considered to be a small job and most wont take it  

Thank you. 

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the last time I investigated that system I could not find a spool valve to adjust, just steering cylinder replacement. There is not even a diagram of the internals or how to disassemble it

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For the cost I would just go with a hyd ststen and say the #$^% with overpriced volvo or adapt a Mercruiser cylinder in its place.

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