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Verado Power Steering
|Author||Topic: Verado Power Steering|
posted 12-21-2008 07:46 PM ET (US)
How much pressure is output by the pump [in a Mercury Verado power steering system]? Thanks,
posted 12-21-2008 08:14 PM ET (US)
[Recommended abandoning this discussion and moving it to another website.]
posted 12-22-2008 10:20 AM ET (US)
This topic is well within the range of discussion for this forum, and there is no need to abandon it.
The goal of the power steering system seems to be twofold:
--reduce the effort required at the helm
--reduce the number of turns of the wheel needed
These two aspects of the steering system are related.
The pressure in a hydraulic steering system is applied to the steering ram. The pressure in the ram is not particularly high--it is only as high as necessary to move the ram. Pressure does not build up in the system unless there is resistance to movement of the steering arm of the motor. Thus the pressure in a Verado power steering system is no higher than in a manual system which is moving the same motor.
To move the motor faster does not require more pressure--it requires more work, that is, you have to supply the same pressure at a higher flow. The power pump supplies more volume of fluid.
The reason the steering effort at the steering wheel is low is because there is an amplification of the pressure in the system. If you were to move the motor to the end of its range and continue to turn the wheel, you probably could build up some higher pressure in the steering system. However, you can do this as well with a manual steering system. In most helm pumps there is a release valve which actuates to relieve the pressure before it become too high and causes damage to the ram and other components. I imagine that there is a similar relief in the Verado power boost system.
posted 12-22-2008 11:37 AM ET (US)
There is another variable that has to be considered regarding pressure in an hydraulic steering system. The pressure in the hydraulic system varies with the design of the ram. The surface area of the ram actuator receives the pressure of the hydraulic fluid.
If we need a force of 50-lbs to move the ram (because that is the force needed to move the motor to which the ram is attached) and the ram has a surface area of 1-square-inch, then the pressure needed to cause movement is going to be 50-pounds-per-square-inch (50-PSI). If the actuator has a surface area of 2-square-inches, then the pressure in the ram only needs to be 25-PSI to produce an output force of 50-lbs.
In this regard, the pressure in the Verado power steering system might be different than in an equivalent manual system because there could be a difference in the design of their rams.
The tradeoff is that with a larger actuator we will need to provide more volume of fluid. If we want to move the actuator 1-inch, with a 1-square-inch actuator we will only have to provide a 1-cubic-inch volume of fluid. With a larger actuator, we will have to provide more fluid volume.
The input for hydraulic steering is the steering wheel, but it is really an hydraulic pump. Various steering wheel pumps have different output volumes, usually indicated by a certain volume per turn of the wheel.
posted 12-22-2008 08:24 PM ET (US)
Are you discussing power steering or hydraulic steering? I have a Verado 175 and believe it is hydraulic. I think it is somewhat hard to turn the wheel under a load. Mike
posted 12-23-2008 12:38 AM ET (US)
The Verado steering system is a hydraulic system which employs an electrically operated hydraulic boost pump.
posted 12-23-2008 12:58 AM ET (US)
The power steering system is mandatory on all the six-cylinder Verado motors, but I believe it is an option on the four-cylinder models. I have also piloted a four-cylinder Verado which lacked the electro-hydraulic boost or power steering, and I commented on the helm effort needed. You can read that article in the archives at
posted 12-23-2008 04:54 PM ET (US)
Yes, I reviewed your report and my boat is the 200 Dauntless with the 175 Verado, similar to the one you tested. I agree, mine must not have the power assist just as you described. It is not too difficult to turn, but you can tell it has no power assist.
Thanks for the response and clarification.
posted 12-24-2008 10:09 AM ET (US)
Jim, found your reply helpful, thanks. Trying to figure out the best way to avoid using their pwr hungry electric pump.
posted 12-25-2008 12:31 AM ET (US)
Marine technical writer Charles Plueddeman mentions in an article (see URI below) comparing the Verado power steering system to a similar system sold by Teleflex which can be re-fit to just about any motor:
"The TeleFlex system differs from the Mercury Verado power steering system in that its electric pump only operates when it detects steering input from the helm--if you are simply idling or running a straight course, the electric pump does not operate. The Verado pump is always on, and in my experience it's also somewhat noisier than the TeleFlex pump."
I was very surprised to learn that the Verado power steering pump is always running. Since it is an electrical pump that means it is always demanding electrical current from the boat battery. I had not seen that mentioned before, and it seems quite unusual. If you check the recommended size of the wiring that is run to connect the power steering boost pump to the battery, the gauge of the wiring is sized for about 60-amperes of current flow. There is a lot of electrical current capacity available to run that boost pump motor. I cannot imagine that it pulls that kind of current all the time.
Charles Plueddeman is the editor at large for BOATING, which claims to be the nation's largest boating magazine.
posted 12-26-2008 12:20 AM ET (US)
During a video interview recorded by boattest.com, Tom Burkhard, who was at the time the General Manager, Control & Rigging System (apparently for the Verado product line), also mentions that the Verado hydraulic steering system has hydraulic fluid continuously circulating through the helm steering wheel pump. He says:
"We came up with our own hydraulics power steering system with a continuous flow pump ...There's a continuous flow pump of hydraulics that goes to the helm. The helm releases the valving. The lock-to-lock is a lot smaller, and so you get a lot tighter...turning radius. Obviously there's absolutely no feedback, and the engines don't transmit any torque back into the steering handle at all."
This confirms the observation by Plueddeman that the electrical-motor-driven hydraulic power steering pump in the Verado system is running all the time.
posted 12-27-2008 11:07 AM ET (US)
I don't know the wire gauge but the fuse protecting that wiring is a 90 amp according to a 2004 Verado Installation Manual and the Mercury Service Manual, SmartCraft DTS (Version 07).
I would think that if there is no steering input (the hydraulic fluid is just circulating to the helm and back to the pump), the current draw could be quite low depending on flow rate. If you are turning with a lot of resistance at the engine, the current draw would be related to the hydraulic horsepower:
I have to take exception to Mr. Burkhard's quote. Turning radius on a vehicle is measured by turning the steering wheel to the stop in one direction and measuring the radius of the circle that is scribed by one of the tires. How is the turning radius measured in a boat which would be very dependent on boat speed? Less turns lock to lock would give quicker steering response.
So, anyone know how much pressure is output by the Verado power steering pump?
posted 12-28-2008 12:05 PM ET (US)
I have also noticed that the size of the hydraulic lines attaching to the Verado steering ram are rather small in diameter, and I also inferred that they must be operating at a relatively higher pressure (and proportionally less flow). I don't know what the pressure in the system is.
As for the current, that 90-ampere figure is a huge amount of current. That must only be drawn when very high actuating force is needed.
From all this discussion about the electrical pump and how it is continuously flowing, a new question has arisen:
What happens in a Verado engine steering system if the electrical pump fails? Do you lose the ability to steer the boat completely? From what has been revealed here, that the helm pump is really only a valve control device, it sounds like if the electrical pump fails the entire steering system is lost.
posted 12-28-2008 02:48 PM ET (US)
the pump will steer if power is lost, albeit hard....go turn one when the boat is off, you'll see. I can still turn the wheel with a knob with one hand....
posted 12-28-2008 05:27 PM ET (US)
Further browsing led to the discovery that maximum draw of the pump should be 75 amps.
posted 12-28-2008 06:06 PM ET (US)
According to the same Mr Burkhard mentioned above, the huge draw occurs when people "bind" the pump and hold it against the stop as in a very tight turn. Normal use is considerably less than 75 amps.
posted 12-28-2008 09:47 PM ET (US)
Glen--Thanks for the information that the Verado steering system will still function even if power to the electrical boost pump is lost. That observation helps me to resolve a conflict with the statement of the Mercury spokesman (above) where he says "the helm releases the valving." I made the inference from that statement that perhaps the helm did not contain a conventional pump that could initiate a flow of hydraulic fluid itself. In that regard it sounds like the power steering system is similar to an automobile. If the power boost is lost, you can still steer, albeit with much higher effort.
posted 12-29-2008 07:36 AM ET (US)
As always appreciate your replies. It is good to know there is backup in event of pump failure. You'd think Merc's continuously running system would get fluid and pump rather hot. Has anyone checked these temps?
What kind of reports do we have concerning steering/pump failures? The Teleflex system recommends a oil cooler for some applications
To me it's a bit odd that Merc would use TRW's motor vehicle steering system pump. Possibly it was because of the pump's reliability. Have to wonder if the same pump used in a vehicle is a continuous run or with a system that detects steering input as the Teleflex is supposed to do.
So why did Merc go with a power hungry electric steering pump rater than using a engine driven pump? Realize that would be robbing power from the engine but with a bit of electrical engineering it could have been done to reduce that since most continuous pump output would be required at lower power setting.
posted 12-29-2008 10:17 AM ET (US)
I recall reading that yes there was a problem with the temperature and I believe that a longer hose between pump and helm was used to cool the fluid.
posted 12-29-2008 11:26 AM ET (US)
The higher temp can create a "whine' but no failures have bben reported to date of any significance. A steering shunt spliced in the line in late 2005 cured this.
And no thanks, nothing more robbing power from the engine and adding complexity please.
Hydraulics can be almost as effortless, but the small amount of turns using PS lock to lock is nice. To get seastar to be close to the effort involved, it will take multi cylinders which will double the amount of wheel turns as now.
Merc tech service does not have a PSI # that they can find. It is a variable PSI to boot, so the amount is constanly changing. I have one other souce looking for it.
posted 12-29-2008 02:14 PM ET (US)
Mercury's approach to power steering using an electrical pump seems to be the "right" way to go, if you take a lead from modern automotive design. Cars are taking more devices to electrical power and getting away from crankcase driven power take off. I think it is the parasitic loss in the belts and pulleys that concerns the car guys, as they are always looking for the absolute best in fuel economy.
OMC had a power steering system that ran off the engine. John Flook's 225-HP V6 (a sister to my engine) had it; he removed it.
posted 12-29-2008 04:10 PM ET (US)
"Cars are taking more devices to electrical power and getting away from crankcase driven power take off. I think it is the parasitic loss in the belts and pulleys that concerns the car guys, as they are always looking for the absolute best in fuel economy." -- JimH
I think it could be some of that but also it could be a matter of convenience. The engineers can locate the power assist electrical appliance just about anywhere in the engine compartment or elsewhere and at any angle and distance relative to the crankshaft. If the same appliance is driven off the crankshaft by belts, the shaft of the appliance usually has to be co-axial with the crank shaft or have a complicated mechanical driving arrangement. So going electrical provides a degree or two of design freedom.
posted 01-05-2009 08:55 AM ET (US)
Going to an electrically powered power steering pump was probably a good move in terms of eliminating a power take off on the engine with a belt and pulley, and considering there is a supercharger to be driven, a belt and pulley arrangement might have been impractical on the Verado. On the other hand, running the electrical motor all the time, even when not needed, is not an energy conserving approach. The electrical power has to come from somewhere, and ultimately it come from the engine via the alternator output. As suggested above, the electrical power demand must not be too high to just run the motor when the load is minimal.
posted 01-06-2009 11:19 AM ET (US)
My recollection is that the Evinrude 225 with the integrated power steering weighed about 15 lbs more than the non power steering version. I assume the Verado steering pump weighs about the same. In view of design freedom considerations, not putting the power steering pump under the cowl allowed the engineers to keep its weight off the transom and its bulk from consuming precious space under the cowl.
posted 01-06-2009 11:41 PM ET (US)
Though not a fan of a motor pump running 24/7, the majority of the running time should be bypassing fluid and not loading the motor down and consuming as much current as when course corrections are made. DC motors generally are not known to have a long life but modern engineering has probably extended time between failures. Would like to know about the high time, commercial/government Verados in service and how many motor pump failures the operators have had. Possibly the more use the better since these pumps were originally designed for nonmarine continuous run applications.
posted 09-13-2009 10:57 PM ET (US)
I recently purchased a boat with a 2007 225 Verado . Everything is running great except for the fact that the steering is extremely stiff. The fluids are fine and I bled the system( at least I think I bled enough out) but it is still stiff? Is there is anything else I should do? I have heard that this system should be super smooth and easy to work. Oh, When I open up the bleed screw and crank the wheel the motor moves effortlessly in the opposite direction( it obviously won't go back as the system is open) Any thoughts????
posted 09-13-2009 11:28 PM ET (US)
You might still have air in the system. Bleed until there is a solid stream of fluid, no bubbles. The oil can be reused if your careful not to contaminate it.
posted 09-14-2009 10:27 PM ET (US)
Are you following the recommended bleeding procedure per the service manual with pump running? No normal pump pressure specs available in the manual I have. The only spec is it shall not exceed 75 amp current draw while operating.
Filling Power Steering System with Engine Running
posted 05-31-2015 11:27 AM ET (US)
Just took my 2007 235 Conquest with 250 Verado out for a sea trial after sitting up for six months. Steering was terrible, with lots of play around dead center and lots of turns of the wheel required for any response.
So after reading this thread, I topped up steering fluid and bled the system as per the previous poster's instructions. A positive feel has returned to the steering, but it is apparent that there is no change in steering effort with the engine off as compared to on; thus, I'm getting no power assist.
Any suggestions for further troubleshooting? I suspect that I"m approaching my Peter principle level of incompetence, but if there's something relatively simple to try I'd like to try it prior to going through the hassle of getting the boat to the dealer.
Any suggestions are welcome.
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