Saildrive corrosion: galvanic isolation and grounding

[Plevier]

OK, that makes sense, thank you. I confess that I didn't spend much time testing if the saildrive was indeed isolated: I had read on this forum that only some of them were, and the screws didn't look like they had insulators on them. I thought that my system relied on the entire engine being isolated.

So in my picture above, which of the screws should have the insulation? From the exploded diagram it looks like it is the interface between the grey and the green, but this does not tally with the info given in this post: http://www.ybw.com/forums/showthrea...Saildrive-isolation-how&p=3961352#post3961352

Between the grey and the green. The other post is not correct.

 

[nigelmercier]

... From the exploded diagram it looks like it is the interface between the grey and the green, but this does not tally with the info given in this post: http://www.ybw.com/forums/showthrea...Saildrive-isolation-how&p=3961352#post3961352

Between the grey and the green. The other post is not correct.

Strange, because in this picture from further down the above thread the washers do look like insulators, and the screw holes appear oversized:

 

[Stork_III]

Strange, because in this picture from further down the above thread the washers do look like insulators, and the screw holes appear oversized:

Here http://www.marinepartseurope.com/en/volvo-penta-explodedview-7746410-21-2438.aspx shows also insulation between bellhousing and block Bush Item 30 on bolt/screw item 33. Maybe that some bolts pass through gearbox casing and housing so insulation at both areas.

 

[VicS]

Here http://www.marinepartseurope.com/en/volvo-penta-explodedview-7746410-21-2438.aspx shows also insulation between bellhousing and block Bush Item 30 on bolt/screw item 33. Maybe that some bolts pass through gearbox casing and housing so insulation at both areas.

But thats a diagram for the MD2010

 

[Stork_III]

But thats a diagram for the MD2010

Same principle for other MD series http://www.marinepartseurope.com/en/volvo-penta-explodedview-7740690-21-4006.aspx

http://www.marinepartseurope.com/en/volvo-penta-explodedview-7740690-21-4007.aspx

http://www.marinepartseurope.com/en/volvo-penta-explodedview-7740690-21-4009.aspx

 

[Plevier]

Same principle for other MD series http://www.marinepartseurope.com/en/volvo-penta-explodedview-7740690-21-4006.aspx

http://www.marinepartseurope.com/en/volvo-penta-explodedview-7740690-21-4007.aspx

http://www.marinepartseurope.com/en/volvo-penta-explodedview-7740690-21-4009.aspx

But that's not with a sail drive.

 

[VicS]

Same principle for other MD series http://www.marinepartseurope.com/en/volvo-penta-explodedview-7740690-21-4006.aspx

http://www.marinepartseurope.com/en/volvo-penta-explodedview-7740690-21-4007.aspx

http://www.marinepartseurope.com/en/volvo-penta-explodedview-7740690-21-4009.aspx

Ok they are the same, I know tha,t ..... they are for the MD 2020, MD 2030 and MD 2040


Now show me the same insulating components on the parts diagram for Nigels engine

 

[Stork_III]

Ok they are the same, I know tha,t ..... they are for the MD 2020, MD 2030 and MD 2040


Now show me the same insulating components on the parts diagram for Nigels engine[/QUOTE

I'd assumed Nigel had a MD20** type engine. If not haven't a clue.

 

[VicS]

Ok they are the same, I know tha,t ..... they are for the MD 2020, MD 2030 and MD 2040


Now show me the same insulating components on the parts diagram for Nigels engine[/QUOTE

I'd assumed Nigel had a MD20** type engine. If not haven't a clue.

IIRC he said it was an MD22P

 

[Stork_III]

But that's not with a sail drive.

Why not.

 

[nigelmercier]

IIRC he said it was an MD22P

Correct, originally with a 120S saildrive, now a 130S.

 

[VicS]

Correct, originally with a 120S saildrive, now a 130S.

But only the 130S leg? You have retained the old upper gearbox?

 

[Plevier]

Why not.

If you look at the saildrive drawing http://www.marinepartseurope.com/en/volvo-penta-explodedview-7748580-44-7620.aspx and here http://www.volvopenta.com/VOLVOPENT...NGINES/C_DIESEL_SAILBOAT/PAGES/SAILDRIVE.ASPX you'll see that the insulation is on the SD gearbox to flange bolts.

The SD to bellhousing adapter plate is different from the in line gearbox adapter plate shown in the drawing you link to, AFAICS.

I attach a photo of a 130 SD being removed from a D1-20 engine, clearly showing the insulation.View attachment 27958

 

[nigelmercier]

But only the 130S leg? You have retained the old upper gearbox?

Yes, only the parts below the large rubber hull seal were replaced. As far as I know, the remainder of the engine and gearbox is as originally fitted.

 

[Stork_III]

If you look at the saildrive drawing http://www.marinepartseurope.com/en/volvo-penta-explodedview-7748580-44-7620.aspx and here http://www.volvopenta.com/VOLVOPENT...NGINES/C_DIESEL_SAILBOAT/PAGES/SAILDRIVE.ASPX you'll see that the insulation is on the SD gearbox to flange bolts.

The SD to bellhousing adapter plate is different from the in line gearbox adapter plate shown in the drawing you link to, AFAICS.

I attach a photo of a 130 SD being removed from a D1-20 engine, clearly showing the insulation.View attachment 27958

I see what you are saying, but where is the bellhousing for the saildrive version then. Surely VP don't make different bellhousings for shaft and saildrive? It looks to me as if the insulation on the MD20** series is in both places for saildrive.

 

[Plevier]

I see what you are saying, but where is the bellhousing for the saildrive version then. Surely VP don't make different bellhousings for shaft and saildrive? It looks to me as if the insulation on the MD20** series is in both places for saildrive.

I suspect the bellhousing is the same but the rear attachment plate different, but you could be right.
But there doesn't appear to be any insulation at that point on Nigel's engine http://www.marinepartseurope.com/en/volvo-penta-explodedview-7746710-21-2865.aspx

 

[Stork_III]

I suspect the bellhousing is the same but the rear attachment plate different, but you could be right.
But there doesn't appear to be any insulation at that point on Nigel's engine http://www.marinepartseurope.com/en/volvo-penta-explodedview-7746710-21-2865.aspx

Extract from Owners manual for MD20** series. Page 39
3. The drive/Reverse gear AND flywheel cover are electrically isolated from the engine and must never be used as a ground.

I agree the MD22P pages don't show isolation flywheel cover/engine.

 

[nigelmercier]

Extract from Owners manual for MD20** series. Page 39
3. The drive/Reverse gear AND flywheel cover are electrically isolated from the engine and must never be used as a ground.

I agree the MD22P pages don't show isolation flywheel cover/engine.

I've searched the folders containing my Bavaria and Volvo Penta manuals, the word "isolated" does not appear.

 

[Plevier]

I've searched the folders containing my Bavaria and Volvo Penta manuals, the word "isolated" does not appear.

Nonetheless it's in at least the 200x series, the MD20xx series, the D1_xx series and the SD130 brochure and parts list so it might be a good idea to implement it.

 

[VicS]

it might be a good idea to implement it.

That may be lot easier to say than do.
At the very least.
It will need an insulating "plate" inserted between the gearbox and the bellhousing adapter plate and the gearbox to adapter plate mounting bolts will require insulating sleeves where they pass through the gearbox flange as well as insulating washers under their heads.

If its not already isolated one has to ask why isn't it ?