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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 16107
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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1988 Mercruiser 4.3/Alpha One power assisted steering problem

Customer Question

1988 Mercruiser 4.3/Alpha One power assisted steering problem since I’ve had the boat. The steering has been tested as outlined in Mercruiser Service Manual #6 using Power Steering Test Gauge, hoses, fittings and plugs Part No. 91-38053A3. All tests good. It is difficult to steer at all speeds being more difficult to the left than to the right when on plane. If I rack the wheel hard I can feel the assist come in briefly. It’s as if the control valve spring and the control valve adjustment spring are holding the valve spool in position with greater force than it takes for the steering cable to move the stern drive.
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hi Al, my name is ***** ***** I will be helping you today.
Have you replaced the steering cable yet?
Customer: replied 2 years ago.
Steering cable is free as a bird when the clevis pin is removed from the hydraulic unit
Expert:  Jason replied 2 years ago.
Bad cables will still turn freely when disconnected. They will only drag when there is a load applied to it. And the greater the load the more they will drag. Do you remember the kids toy called a Chinese finger trap?
Customer: replied 2 years ago.
We may disagree but the cable is fine so with that assumption what would you question next?
Expert:  Jason replied 2 years ago.
There are only 3 parts to the power steering system. The cable, the pump, and the actuator. When troubleshooting these issues in the shop we check pump pressure first. If that is good we do the cable 2nd. If that doesn't fix it we change the actuator. So if your are sure the cable is good, the only other thing there is to the system is the actuator. Does that make sense?
Customer: replied 2 years ago.
Yes, as I stated all test results were OK But here is the dilemma The actuator PN 90496A 5 is NLA. I found A new factory unit at Seaway and after installation I get the same results. I'm not trying to be a jerk here But I'm starting to scratch my head.
Expert:  Jason replied 2 years ago.
That's why I had asked if you changed the cable.....You said the steering was stiff at all speeds. On a boat the power steering is a part time assist, and only kicks in when the boat is up on plane. If you take 2 identical boats and give one power steering and have the other non power steering you would not notice the difference in the effort it takes to turn the wheel when the boat is not up on plane. At idle and slower speeds, they would steer identically. Does that make sense so far? Have you ever taken an old steering cable and cut one down the middle to see what actually happens inside, and what makes a cable go bad?
Customer: replied 2 years ago.
I've replaced many steering cables and I understand the power steering is an assist in this case due to the open flow of the hydraulic fluid through the system when the control valve is in the neutral position. Thank you for your professional advice.
Expert:  Jason replied 2 years ago.
You are very welcome. Was there anything else I could help you out with on the issue?