Anode Trim Tab Function on Mercruiser 175

[sweet41k]

I have an 87 Mercruiser 175 4.3L that recently had a problem. I just removed the outdrive and started taking it apart when I noticed the hole in the lower gear case above the prop. There is also a loose bolt hanging down that spins freely. Only the threaded part of the bolt is showing. Interestinly enough I've owned the boat for a few years and I know it's never had a trim tab bolted on there. I changed the prop a couple years ago and never noticed it then either. What is the purpose of this, it's ran fine for several years without it? When looking to order one there are several different models listed for the same drive with no information on dimensions. Some look longer than others amd some have no fin at all. If it's too long it will hit the prop I think. Is mine supppose to have one and which one is best? I have a 14.25x19p SS Turning Point prop.

 

[Rocky_Road]

Re: Anode Trim Tab Function on Mercruiser 175

I have the same size prop...and this is the one that gave me the necessary clearance:

 

[dubs283]

Re: Anode Trim Tab Function on Mercruiser 175

the trim tab anode is a sacrificial metal piece that serves two purposes

1. to counteract the side force of the rotating prop on boats that are not equipped with poer steering

2. to prevent corrosion from water and stray current to erode the drive/prop

 

[sweet41k]

Re: Anode Trim Tab Function on Mercruiser 175

Rocky Road what is the part number for the one you pictured? Do I still need this if I have power steering?

 

[cr2k]

Re: Anode Trim Tab Function on Mercruiser 175

They make an anode that has no trim tab which is used with power steering.
MC PN 76214, 76214 T3, or 76214Q5

Or order from NAPA or a Sierra Supply dealer as PN 18-6016

 

[Rocky_Road]

Re: Anode Trim Tab Function on Mercruiser 175

Rocky Road what is the part number for the one you pictured? Do I still need this if I have power steering?

The Mercrury part number is 822777Q 1.

You can get one here: http://www.psepmarineparts.biz/store/mercruiser_anodes_gear_housing.htm

I found mine at West Marine....

As for if you need one with power steering...not really. But there is a lot of discussion as to if one would benefit the life of your steering components, since all single prop outdrives have some degree of torque steering...even if your power steering 'hides' that fact. I don't have PS, so I needed it...but if I did have PS, I would still be running one (slightly turned to the left)!

Your call...!

 

[IVAZ]

Re: Anode Trim Tab Function on Mercruiser 175

You don?t need the anode with the trim tab. I have a 1988 Merc 4.3 (175 hp) and it has the anode that is just flat. There is no torque steer at all. You can actually let go of the steering wheel and it will hold its course. No reason to run an anode with a tab to compensate torque steer that doesn't exist.

 

[Rocky_Road]

Re: Anode Trim Tab Function on Mercruiser 175

You don?t need the anode with the trim tab. I have a 1988 Merc 4.3 (175 hp) and it has the anode that is just flat. There is no torque steer at all. You can actually let go of the steering wheel and it will hold its course. No reason to run an anode with a tab to compensate torque steer that doesn't exist.

Torque steer DOES exist...pure physics. The power steering 'masks' the torque. What you are feeling at the helm is the power steering compensating for the torque steering that ALL single prop outdrives generate. This is not theory....

Like I tried to make clear...power steering corrects the helm experience, but does not change the fact that there are torque steer pressures applied to the steering system, and the outdrive components. Some boaters use the trim tab to take this strain off of their steering system components. Not to mention that the finned trim tab gives you added anode for corrosion purposes.

Finned tab...or flat...it is the owner's decision!

Happy boating!

 

[IVAZ]

Re: Anode Trim Tab Function on Mercruiser 175

Torque steer DOES exist...pure physics. The power steering 'masks' the torque. What you are feeling at the helm is the power steering compensating for the torque steering that ALL single prop outdrives generate. This is not theory....

Like I tried to make clear...power steering corrects the helm experience, but does not change the fact that there are torque steer pressures applied to the steering system, and the outdrive components. Some boaters use the trim tab to take this strain off of their steering system components. Not to mention that the finned trim tab gives you added anode for corrosion purposes.

Finned tab...or flat...it is the owner's decision!

Happy boating!

I will respectfully disagree Rocky. Torque steer occurs when the steering wheel turns to a side due to torque from the engine. Since the boat is equipped with power steering it won?t turn to any side. If I never have to correct the steering wheel how can I claim to have torque steer? Even though the torque is still there it won?t steer the boat due to the power steering. It absolutely has to be steering the boat for it to be called "torque steer".
I do understand what you mean, I think. I think you are saying he should put the trim tab to counter the "energy" we know is there even though it doesn?t affect the boat. I kind of see that point but I find it very unnecessary. The boat just has no use for it. Its there to fight torque steer which doesn?t exist because of the power steering. Lots of boats are running the flat anode with no ill effects.

 

[Rocky_Road]

Re: Anode Trim Tab Function on Mercruiser 175

I will respectfully disagree Rocky. Torque steer occurs when the steering wheel turns to a side due to torque from the engine. Since the boat is equipped with power steering it won?t turn to any side. If I never have to correct the steering wheel how can I claim to have torque steer? Even though the torque is still there it won?t steer the boat due to the power steering. It absolutely has to be steering the boat for it to be called "torque steer".
I do understand what you mean, I think. I think you are saying he should put the trim tab to counter the "energy" we know is there even though it doesn?t affect the boat. I kind of see that point but I find it very unnecessary. The boat just has no use for it. Its there to fight torque steer which doesn?t exist because of the power steering. Lots of boats are running the flat anode with no ill effects.

I have no real arguement with your statement that the power steering handles the torque steering for the driver...that is a 'given'!

But consider this:

The same boat without power steering, or a finned trim tab, would have to be man handled to steer straight. Introduce the power steering, and the pump (and it's related components) are doing all of the work, on your behalf, to steer straight. Go back to the first scenerio, and recall just how much effort this was manually required...and realize that your power steering components are fighting those same forces! I submit that this is hard on the system, and that this can eventually cause something to wear out before it's time. Why not take some of this 'strain' off of your power steering setup?

Ideally...if I had power steering, I could find a way to disengage the assist, and set my trim tab to steer as straight as possible without a great deal of manual correction. Then...I could use the power steering, knowing that I was placing the least amount of stress upon all of those costly components! I doubt that you would argue that this would be the best scenerio....

A finned trim tab...set several 'clicks' to the left (as are almost 99% of the non power steering rigs), would ease my mind a great deal.

Just my opinion...not even worth an inflated $0.02!

Happy baoting!

 

[IVAZ]

Re: Anode Trim Tab Function on Mercruiser 175

Rocky,
I hear ya buddy, you make sense. I?m going to say this and then I?m going to leave it alone.
Even though I do understand what you are saying I still don?t agree. My boat is 21 years old and is still sporting its original steering components. Considering they all still work great I bet they still have many seasons left in them.
I also think if the tab made a noticeable difference in component wear Merc would have installed one on every drive. I have never heard of steering components wearing out due to no trim tab. In the time I have been here at iboats I have only read about a few boats that had steering components wore out (actual parts that hold steering components, i.e. parts of the gimbal etc). If I recall correctly the boats were 30+ years old with no power steering. I?m not blaming the lack of PS, just their age.
It doesn?t make sense to disconnect the PS pump to set up a tab that?s not supposed to be there.

 

[Rocky_Road]

Re: Anode Trim Tab Function on Mercruiser 175

That's cool, IVAZ...we have 'solved' that issue!

Now...about the economy.

 

[IVAZ]

Re: Anode Trim Tab Function on Mercruiser 175

That's cool, IVAZ...we have 'solved' that issue!

Now...about the economy.

Hey I bet we both agree on that one, it SUCKS!