Outdrive piston off

[charlg]

I had my boat lifted today to have it set up for a trailer. While it was up, I noticed that the piston on the port outdrive was only be held on by the top bolt. The lower bolt (closest to the transom) was missing the cap, bolt and washer. I had noticed the last time out that I had some play in the steering, which was new. I got the replacement parts from the dealer and he said he had never heard of the bolt coming off. It was a lucky thing that I had the boat lifted when I did and caught it before it did some real damage.

Any idea why it would have come off?

 

[Stray Cat]

Are the threads ok?

 

[jg300da]

Electrolysis. I had that happen to a friend who was slipped next to a guy who was using a portable battery charger on his boat. Those nuts under the plastic caps are zinc, just like your anodes. He pulled the boat after hearing a banging noise from the outdrive and found both nuts dissolved away.

 

[charlg]

Electrolysis. I had that happen to a friend who was slipped next to a guy who was using a portable battery charger on his boat. Those nuts under the plastic caps are zinc, just like your anodes. He pulled the boat after hearing a banging noise from the outdrive and found both nuts dissolved away.

I did notcie that the skeg on that same outdrive had some corrosion, but the other did not. Is it possible for only one outdrive to be affected by electrolysis?

 

[Lazy Daze]

JG - the nuts holding the hydraulic rams on are SS. Maybe you're friend was referring to something else?

I've never heard of that happening, either. Jeff's thought is about the best I can think of. That's really odd. :huh:

Maybe someone in your marina was missing one and didn't want to buy a new one!:smt001

 

[jg300da]

Not these. Definitely zinc. The boat was a 2002 and all four nuts, front and rear were zinc. Verified at SS3 Copaigue. The threaded rod at the rear as well as the washers were stainless. He replaced them with stainless nuts.

 

[Lazy Daze]

Not these. Definitely zinc. The boat was a 2002 and all four nuts, front and rear were zinc. Verified at SS3 Copaigue. The threaded rod at the rear as well as the washers were stainless. He replaced them with stainless nuts.

Really?! :wow: Boy, I wonder whose brilliant idea it was to put those zinc nuts on there! :smt101

 

[wish2fish]

I did notcie that the skeg on that same outdrive had some corrosion, but the other did not. Is it possible for only one outdrive to be affected by electrolysis?

do they have separate protection systems?

 

[Lazy Daze]

I did notcie that the skeg on that same outdrive had some corrosion, but the other did not. Is it possible for only one outdrive to be affected by electrolysis?

If you're only seeing corrosion on the skeg, I wouldn't worry about it at all. Maybe the paint on that skeg was a little more worn away.

How do the other anodes compare between the port and stbd engine? Same relative rate of wear?

 

[charlg]

If you're only seeing corrosion on the skeg, I wouldn't worry about it at all. Maybe the paint on that skeg was a little more worn away.

How do the other anodes compare between the port and stbd engine? Same relative rate of wear?

All of the anodes on both looked fine.

 

[Lazy Daze]

All of the anodes on both looked fine.

OK.

Follow up question though... They didn't look brand new, did they? That would be bad. They should all have some degree of wear. But, it should be relatively consistent.

 

[charlg]

OK.

Follow up question though... They didn't look brand new, did they? That would be bad. They should all have some degree of wear. But, it should be relatively consistent.

Not brand new, but they still had a lot of meat left. The tricky part of buying anodes for me is that I slip in fresh water, but frequently go through the locks into salt.

 

[Lazy Daze]

Not brand new, but they still had a lot of meat left. The tricky part of buying anodes for me is that I slip in fresh water, but frequently go through the locks into salt.

As long as they're showing wear, which it sounds like that's what you're saying, then that's good.

Are you using Aluminum anodes, specifically Navalloy? That is what you want for mixed waters. Check this brand out: http://www.performancemetals.com/default.asp

Much cheaper than the Merc set, and excellent quality. Made in the USA, too.

Here's a good write-up that one of my co-workers did about corrosion: http://petersmarine.blogspot.com/2009/04/galvanic-corrosion-what-is-it-and-how.html