Styring vrenger til venstre ved pådrag

[Ibiza 8.1L V8]

Hei.

 

Har fått et problem med styringen og hvordan båten reagerer når jeg gir på.

 

Har Mercruiser Bravo1 drev som er servoassistert og mekanisk styring som har funket helt fint.

Etter båten var på service og drevet var tatt av så har båten blitt livsfarlig å kjøre. 

Hver gang jeg nå gir på enten det er for å komme opp i plan eller om det er fra 30-40knop så vrenger styringen til venstre. kreftene er så kraftige at man havner i sjøen hvis man ikke er oppmerksom. Samme skjer mot høyre når jeg slakker av fra 40 og ned..

 

Verkstedet sier at de har smørt opp drevet og at det derfor glir lettere, men det har jeg ikke tro på.

De mente også jeg hadde slark i styringen og at det også var årsaken, men styringen har hvert lik i flere år og har ikke hatt dette problemet da.

Har sett på styresnekken at vaieren beveger seg uten problemer når jeg vrir på rattet.

 

Noen som har peiling på hva som kan ha skjedd her?

[Spannerman]

I am a Mercruiser engineer and there are no lubrication points on Bravo drives to make them easier to turn, so your workshop is talking rubbish.

Do you have a fin anode at the back of the cavitation plate which has been changed or moved? I always mark the angle they are mounted at when I replace them as it will cause this problem if not adjusted to suit that boat.
What you have  is called prop torque steer, all outboards and sterndrives experience this and it is usually not felt when you have servo steering but can be reduced by using a fin anode under the cavitation plate. But this depends on what propeller you have, if it has raked blades you can get offset fins to clear the blade tips. If the drive turns to the left then you adjust rear edge of the fin to the left which then pushes the drive to the right to cancel out this effect. However its not possible to get this to work for all speeds as the effect varies with speed so you adjust it to work best at your normal cruising speed. If you are sure there is no slack or wear in the steering wire then this could help.

If you had one fitted before the service then it sounds like the workshop have refitted  it incorrectly, they are always mounted with an angle to the left on high horsepower engines  and normal rotation props to eliminate the torque steer.

[Ibiza 8.1L V8]

Hi, and thanks for the pointers, but i have a flat sink anode without a fin, and its the same one i had last year.

So i has to be something else that they have done wrong because it was fine last year, and now its dangerus...

Redigert 6.Juni.2022 av Ibiza 8.1L V8 (see edit history)

[Spannerman]

Does the steering feel normal, or is it heavier to turn than before? Is the oil level correct on the power steering pump? If the drive is moving over to the left then you must feel it on the steering wheel, and its maybe heavy to turn back to the right. The only to components are the power steering pump which normally run for years and the servo cylinder which the steering wire connects to. The cable  nut should be tight and on the tube which comes out of the cylinder and connects to the steering arm you will see to flat sides nearer to the cylinder housing, these must be vertical for it to operate correctly.

The other thing is the floating valve section where the wire connects, if you rock the wheel from side to side you will see the valve body move in and out a few millimetres each way. When driving its should centralise with pressure from the pump, when you turn the wheel the valve floats left or right and lets oil push on the servo piston inside. You could get someone to watch while you drive to see if this is moving itself when driving straight ahead which would mean there is an internal hydraulic fault.

[Ibiza 8.1L V8]

The steering seems quite normal, exept from the violent yanking to the left (and right when decreasing), and no difference turning left or right at a steady speed ex 25knt.. i opened the powesteering reseroair cap and there was some oil, but i dont know how much its supposed to be. 

I will have to check up on thees other things, but i was able to see there was some movement on the thing that is going into the sylinder when turning the wheel but its rocking about 1cm, not millimeters..

 

[Spannerman]

1 cm is ok on the steering cylinder. The oil should be about3-4 cm from the top of the reservoir. Just a question, you haven’t changed to different type of prop?

Its strange that this has only started after the service if everything is the same as before. What you are describing is definitely torque steer as I have experienced this on several boats I’ve worked on, and can vary with speed and trim angle. Normally hydraulic steering stops this feed back or fitting a trimtab fin on the cavitation plate, but you have never had one so it must be something has changed in the steering system.

[Ibiza 8.1L V8]

Ok, same prop also. Reservoir had oil but only 1-2cm. 

 

I totally agree with the torque steer, only the compensation from the servo isn’t there anymore. 
 

the workshop had the whole engine out and the out drive, so many they did something to the servo when installing the engine back in?

 

by the way, there was a little bit pressure opening the servo cap, could it be air in the system from disconnecting engine?

 

Redigert 6.Juni.2022 av Ibiza 8.1L V8 (see edit history)

[Fantino]

Venting procedure is probably worth trying?

 

 

Full downloadable manual here (if it covers correct model): https://d3gqux9sl0z33u.cloudfront.net/AA/AR/wetbristol/downloads/224963/Bravo_stern_drives.pdf

[Spannerman]

I can’t think what the workshop has done as when you remove any Mercruiser engine or drive you don’t need to disturb the servo cylinder. The only thing you do is disconnect the two hydraulic hoses which come from the engine, and after reconnecting it self bleeds if you go lock to lock with the wheel a few times with the engine running.

[Ibiza 8.1L V8]

Hmm, ok thanks they’re going to have a look at it soon, so I guess we’ll see. 
 

thank you. 

[Fantino]

I wouldn’t be too surprised if too little venting is the problem. Have had the same 2 times after having mechanics on board.