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Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I am looking help with the power steering system on

Customer Question

I am looking for some help with the power steering system on my boat.
I have a 1993 mercruiser 5.0 LX with an Alpha one drive.
I recently replaced my power steering cylinder (new part #Mercury 806034A1) and have not got the steering working properly yet.
The system seems to work OK until the steering cylinder encounters the slightest resistance. With the cylinder disconnected from the leg, I can fully extend and retract the cylinder using the steering cable.
When I hook the cylinder back up to the leg and try and steer, the pump starts going over the relief and the cylinder wants to fully extend.
I can move the leg freely and easily thru it's range with the cylinder disconnected.
The new steering cylinder came with three additional ports at the end of the cylinder that my original unit did not have. I believed that these were for controlling the cylinder by an external pilot source so I simply plugged all three and am now thinking this may be my problem.
Any suggestions on what to check?
Submitted: 5 months ago.
Category: Boat
Expert:  Jason replied 5 months ago.
Hi Steve, my name is***** you disconnect the power steering. Or take the belt off the pump. And go and drive the boat in the water. Is the steering tight at all speeds, including idle/slow speeds? Or does it steer okay at low speeds, and only get difficult when you get up on plane?
Expert:  Jason replied 5 months ago.
Hi Steve, it looks like you read my reply. Did you still need help with this?
Customer: replied 5 months ago.
I responded by email - but that may not be the right way to communicate - so I'll try again here.
I will have to wait until the weekend before I can take my boat out on the water & do the testing you asked about.
I haven't driven the boat since changing the steering cylinder. I have just done the testing I described above out of the water.
When out of the water, the steering is smooth back and forth for a narrow arc of the steering angle. If I get outside of the narrow angle in either direction, the steering cylinder tries to extend at full pressure (over the relief).
If I do the water test and find the steering cylinder is trying to extend at full pressure, even at slow speeds, what would be the next step?
Expert:  Jason replied 5 months ago.
Hi Steve. I'm sorry if the website is giving you trouble. When we type back and forth you must be logged into the website and replying back through the website, we do not work through email. That being said, you wrote "If I get outside of the narrow angle in either direction, the steering cylinder tries to extend at full pressure" I don't' understand what you mean by that, can you maybe re-word that for me.Next, what is the story on this problem? When did it last steer correctly? Why was the cylinder replaced? How old is the cable? Is the power steering pump original to the engine or was that changed?
Customer: replied 5 months ago.
Hi Jason,
The steering system was working fine before I replaced the steering cylinder and it has not worked since I installed the new cylinder. The reason I replaced the old one is that it was leaking quite a bit of oil.
The boat is a 1993 - I have owned it for 10 years. I am not sure if either of the components were replaced before I got the boat, but I have never replaced the power steering pump or steering cable.
Here's another try at the "narrow angle".
To turn from full to port to full to starboard, I would spin my steering wheel about 3 revolutions and the drive would swing ~45 degrees from center in either direction,
When I don't have the cylinder connected to the drive, I can freely swing the drive itself ~45 degrees in either direction.
When I don't have the cylinder connected to the drive, I can spin the steering wheel thru the full 3 rotations and the steering cylinder extends smoothly in & out properly. The steering wheel turns effortlessly in both directions.
When I hook the steering cylinder back up to the drive and I start the boat with the drive in the dead center position, I can turn the steering wheel about 1/2 a turn in either direction, The steering feels normal and the drive swings back and forth - maybe 15 degrees in either direction. If I try and spin the steering wheel more than 1/2 a turn, the cylinder goes to full pressure, trying to extend. I can hold the steering wheel against the cylinder extending, but the pump sounds like it is going over relief and it will not back off of the full pressure until I turn the engine off and stop the pump.
It seems to me like there is a problem with the valving inside the cylinder or a problem caused by my blocking off all the ports on the end of the steering cylinder. I have attached a photo to show you the ports I am talking about.
Expert:  Jason replied 5 months ago.
Was that actuator a new in the box mercruiser part? Or something used/aftermarket/or ebay? Did you have to put those plugs in or did they come with the actuator?
Customer: replied 5 months ago.
The actuator was a new in the box mercruiser part - part #806034A1.
In the picture I sent you, the 2 plugs on the LH side of the picture came with the cylinder.
The plug on the RH, I had to buy.
Expert:  Jason replied 5 months ago.
Did you buy that from a local dealer or online? The reason I ask is it doesn't look like 806034A1. Click this link below to pull up a picture, this is the correct actuator. Can you see how this one is different from yours on the left hand side?

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