Steering valve question

[SolidLifters]

Not sure if this is the proper section to post this question in. Some MerCruiser stern drive boats with power steering use a steering valve that's the same as the one on the end of the drag link on a Corvette with power steering. When I had a shop that did a lot of Corvette repair in the 80's and first half of the 90's we replaced a lot of steering valves. So my son just bought a boat with this setup and when the engine is running the steering wheel will turn all the way to the right lock on it's own. When running along, the steering will also be stiff to one side and then suddenly release causing a swerve. I remember that Corvettes with a bad steering valve would often exibit these exact two characteristics. I was never successful in adjusting one on the car that developed this problem, however did adjust some new ones to make them stay neutral. My friend the Mercury dealer says he's never seen the valve cause this type of issue on a boat, but I'm not seeing any other possibilities and the previous owner says the power steering pump is new. What do you guys think?

 

[Antz81]

Not sure if this is the proper section to post this question in. Some MerCruiser stern drive boats with power steering use a steering valve that's the same as the one on the end of the drag link on a Corvette with power steering. When I had a shop that did a lot of Corvette repair in the 80's and first half of the 90's we replaced a lot of steering valves. So my son just bought a boat with this setup and when the engine is running the steering wheel will turn all the way to the right lock on it's own. When running along, the steering will also be stiff to one side and then suddenly release causing a swerve. I remember that Corvettes with a bad steering valve would often exibit these exact two characteristics. I was never successful in adjusting one on the car that developed this problem, however did adjust some new ones to make them stay neutral. My friend the Mercury dealer says he's never seen the valve cause this type of issue on a boat, but I'm not seeing any other possibilities and the previous owner says the power steering pump is new. What do you guys think?

There is a balancing valve that can need adjusting from time to time, this would cause the exact problem you are describing. Not sure exactly where it would be on the boat. If it is the same as a corvette then this is what it would look like:

Adjustment done using the nut under the dust cap on the right.