Corrosion on drive

[Tafflad]

First off background, had Mercury I/O’s for past 20 years never had any corrosion issues.
Have my first Volvo …. New last year 4.3L 280-C Duoprop
The boat is not moored, only done 40 Hrs total, and fully washed down after each use.

Noticed some bubbling of paint on the half round collar immediately where prop joins drive body.
Boat in for it‘s annual service, asked VP to look at corrosion. They did quick examination and reported significant corrosion on the rams, especially around the bonding wires.
The corrosion seems to be under the paint, causing it to bubble.
The dealer said they have never seen corrosion this bad on what is a new drive, the props were changed by this dealer last year …. when they did the PDI.
The main anode on top of drive is in place ( and I clean it before each launch).

.The technician said the SS DuoProp is a lot of Steel, and he was trying to see ‘down’ into prop as there is another anode there … but he could not see it at the time.

they admit there is not even a scratch on the Skeg, it is all pristine, no damage … it’s corroding under the paint.

My view is this needs to be a warranty issue, and they are investigating.
Anybody come across anything like this ? …

 

[muc]

Yes I've seen this a couple of times. It was always an issue with the boats wiring.

 

[Scott Danforth]

New boat means you have a warranty

Corrosion under the paint is normally a bonding issue

 

[Tafflad]

I’ll update once the dealer reports back.

 

[Tafflad]

Yes I've seen this a couple of times. It was always an issue with the boats wiring.

Just a Q …. Understand issue of power Line currents from shore power, causing accelerated galvanic corrosion.
In this case there being no mooring, and as there is no electrical power to the drive, do you mean issue with earthing cables ?

 

[muc]

I should modify this to read.
Yes I've seen this more then a few times. It was ALMOST always an issue with the boats wiring.

A couple of times it wasn’t the boat, next door neighbor of a customer had an “invisible fence“ installed for their water loving dog and had the wires ran down into the water so the dog could swim. Caused major corrosion because they would lower the boat into the water so they could run the boat to listen to the radio. Another time was the customer had a couple of ponds between the house and the lake, had bad wiring to the underwater lighting in the ponds.

For boat wiring issues. Boat builder connected the ground for the CO detector to the boats bonding system. This put current on the bonding system and destroyed the drive. Another was a dealer installed bilge pump float switch that allowed 12 volts to get into the bilge water. Another was a customer that stored his boat in a very damp garage and used an automotive style battery charger. That boat didn’t even have 10 hrs on the meter and had bubbling paint.

I bring these up to illustrate how many different things can cause this problem. The amount of salt in the water or if fresh how acidic or alkaline the water is makes a big difference. You should find someone who is familiar with the issues in your area. Once this starts it will only get worse and no amount of repainting or touching up will ever restore the factory paint job.

Very rarely is this a Volvo or MerCruiser problem, But I have had a bad Mercathode controller and missing/damaged bonding wires.

 

[muc]

Just a Q …. Understand issue of power Line currents from shore power, causing accelerated galvanic corrosion.
In this case there being no mooring, and as there is no electrical power to the drive, do you mean issue with earthing cables ?

There is electric power going through the drive, this is what is causing the problem.

I’m not sure what you mean by “earthing cables”. Boats have two systems, the grounded and the grounding, sometimes called the battery negative and the bonding system. These two systems are usually connected at just one point.

 

[dingbat]

Dissimilar metals corrosion is the by-product of difference in the electrical potential between two surfaces. Something as simple as a loose or missing grounding wire can set the process in motion.

Simple test...set voltmeter to ohms... measure resistance between the ground bolt on the motor and the battery. Should read at or very near 0. Sometimes you get a small residual reading from the probes

Now measure the resistance between rams, ground wire, etc. and the battery post. If your readings is different from the motor ground you found your problem.

 

[Tafflad]

Dissimilar metals corrosion is the by-product of difference in the electrical potential between two surfaces. Something as simple as a loose or missing grounding wire can set the process in motion.

Simple test...set voltmeter to ohms... measure resistance between the ground bolt on the motor and the battery. Should read at or very near 0. Sometimes you get a small residual reading from the probes

Now measure the resistance between rams, ground wire, etc. and the battery post. If your readings is different from the motor ground you found your problem.

That is what I expected when I mentioned ’earthing cables’
The cables that are in place to various metal parts to maintain a common potential.
Its usual to have a star connection, all ’grounding’ cables emanate from a single point …. Giving equi-potential, daisy chaining these cables is always to be avoided,

I can’t check resistances as boat is still with dealer, I asked for update … they are awaiting Resoonse from Volvo.

 

[muc]

Dissimilar metals corrosion is the by-product of difference in the electrical potential between two surfaces. Something as simple as a loose or missing grounding wire can set the process in motion.

Simple test...set voltmeter to ohms... measure resistance between the ground bolt on the motor and the battery. Should read at or very near 0. Sometimes you get a small residual reading from the probes

Now measure the resistance between rams, ground wire, etc. and the battery post. If your readings is different from the motor ground you found your problem.

There are a number of tests that should be done.
There are a few types of corrosion.
Given how little time the O.P. says this boat has spent in the water ——- I would be looking at stray current corrosion.
Does this boat have ACP installed?

 

[QBhoy]

Seen this with boats in a marina with poor shore power installation. But I think you’re suggesting she is not kept in the water. This being the case, surely a continuity issue between the affected area and the anodes.
If you hadn’t mentioned the ram areas being affected and only said about bubbling paint on the gearcase…I’d be worried about an overheated situation.

 

[Tafflad]

Update (or lack of) … been at dealer for a month.
They are still waiting for a response from Volvo.

To confirm .. no shore power issue as not moored, no idea what ACP is.
The boat is a standard 12v battery install … nothing special.

Total Hrs are low - only 40.

Never had an issue with corrosion on any previous boat …. never have DuoProp before, sort of wondering if it’s related to the large amount of Stainless Steel…. The Dual props are a lot of SS.

 

[QBhoy]

Update (or lack of) … been at dealer for a month.
They are still waiting for a response from Volvo.

To confirm .. no shore power issue as not moored, no idea what ACP is.
The boat is a standard 12v battery install … nothing special.

Total Hrs are low - only 40.

Never had an issue with corrosion on any previous boat …. never have DuoProp before, sort of wondering if it’s related to the large amount of Stainless Steel…. The Dual props are a lot of SS.

Definitely not overheating that’s causing this ?

 

[muc]

ACP = Active Corrosion Protection -- this is an impressed current system. Much like the MerCruiser Mercathode system -- but a little smarter.

Yes the 2 S.S. props can cause a problem, MerCruiser had terrible trouble with the Bravo 3 and they had to add some more anodes along with making the Mercathode standard equipment. But that's Galvanic corrosion (dissimilar-metal corrosion) and I don't think that's what your experiencing. From your description of how much time the boat has spent in the water it seems much more likely to be stray current which greatly speeds up the galvanic corrosion.

Volvo has been making drives with 2 S.S. props for a long time and has seen way less corrosion issues.

This probably isn't a Volvo problem, but they are the first place to start. I don't know how it works on your side of the pond. But if this was a friends boat here in the U.S. I would be telling them to call Volvo customer service.

 

[Tafflad]

ACP = Active Corrosion Protection -- this is an impressed current system. Much like the MerCruiser Mercathode system -- but a little smarter.

Yes the 2 S.S. props can cause a problem, MerCruiser had terrible trouble with the Bravo 3 and they had to add some more anodes along with making the Mercathode standard equipment. But that's Galvanic corrosion (dissimilar-metal corrosion) and I don't think that's what your experiencing. From your description of how much time the boat has spent in the water it seems much more likely to be stray current which greatly speeds up the galvanic corrosion.

Volvo has been making drives with 2 S.S. props for a long time and has seen way less corrosion issues.

This probably isn't a Volvo problem, but they are the first place to start. I don't know how it works on your side of the pond. But if this was a friends boat here in the U.S. I would be telling them to call Volvo customer service.

OK it does not have ACP
There can’t be stray currents from any mooring as it’s never moored.
It is under warranty so took it to the main Volvo Penta dealer, they advised that there is corrosion at several places where earthing wires are screwed to rams as well as what I reported on the ‘ collar/cover’ nearest the prop.
If there are stray currents in running conditions then it must be an install issue.
I will phone dealer today.

 

[Tafflad]

Definitely not overheating that’s causing this ?

No .. absolutely sure .... and in any case the location of the corrosion on rams does not get hot. The corrosion is right at the point of the screw fixings of the 'earthing wires'

 

[QBhoy]

No .. absolutely sure .... and in any case the location of the corrosion on rams does not get hot. The corrosion is right at the point of the screw fixings of the 'earthing wires'

Got you. Sure sounds like a galvanic continuity issue then Taff. If you’re using her in the sea…I’d start with changing the anodes over from the very “general use” originally supplied aluminium dual purpose ones, to the zincs. That certainly used to be the case at least. But even still. I’d assume this is still definitely a warranty issue for sure. If you have no luck with the original dealer…try another reputable VP dealer. They are usually pretty good here in the U.K.

 

[Tafflad]

Pretty limited in VP dealers in South Wales…. have a 100 mile round trip to take it to nearest..
I have promoted my call to them tomorrow that if they are still ‘waiting for response’ ,…. I will raise to VP.

 

[Tafflad]

OK not good news ...

After a full month, dealer now phoned they are chasing trading.
When I asked what was update on issue with VP ...they had not reported it, nor do any investigation.
Each week I phoned to be told waiting on VP response .... shocking behavior...
Totally lied to me.

Now I have issue of getting my boat from a closed dealer.

 

[Tafflad]

Post above has a ‘typo’. Dealer is ‘ceasing trading’
The annoying thing is that for a month they kept telling me they were waiting on VP .. now advise they had not investigated the issue nor reported it to. VP for warranty parts claim.

Feel seriously misled by dealer, clear misrepresented the situation.
Will put this in writing to VP and see about finding another dealer.