VP D2-55, saildrive and continuity

[PatrickSeb]

Long story short, problems isolating MS25S saildrive from VP D2-55 engine after renewing flexible coupling at flywheel. Measuring with a multimeter for continuity, and eliminating bolt by bolt etc, I end up splitting engine/gearbox again. With a 2 inch gap and nothing attached to or against the gearbox/drive, I still measure continuity between engine/gearbox (!) Disconnected grounding cables from engine, and still continuity. Continuity through water is my first assumption. But where to begin? All through hull fittings are composite.
Constructive advice and ideas are very, very welcomed

 

[Slowtack]

Throttle and gear cables??

 

[PatrickSeb]

Throttle and gear cables??

Gear cable/bracket disconnected.

 

[VicS]

Long story short,
Constructive advice and ideas are very, very welcomed ☺

Do you find a very low resistance between the engine and sail drive or is it high enough to be accounted for by water in the water intake hose or have you disconnected that anyway.

 

[PatrickSeb]

Do you find a very low resistance between the engine and sail drive or is it high enough to be accounted for by water in the water intake hose or have you disconnected that anyway.

Everything, included water intake hose is disconnected. Had thought of that as a possible culprit ?

 

[RichardS]

How many ohms are you actually measuring?

Richard

 

[VicS]

Everything, included water intake hose is disconnected. Had thought of that as a possible culprit ?

And battery positive and the engine wiring harness?

 

[PatrickSeb]

Everything related to saildrive disconnected, but only water intake, exhaust and negative cables to engine.
Plus cut by master switches. But thanks, will double check by disconnecting battery plus ?

 

[PatrickSeb]

How many ohms are you actually measuring?

Richard

70 ohms before fault searching ?

 

[PatrickSeb]

Update:
This is getting stranger and stranger...
Down in boat this afternoon, and now there is no continuance between separated engine/gearbox(!) Assembled all elements, measuring for continuity for every operation. No continuity UNTIL I affixed the negative cables to the engine block.
So, it appears I have a negative problem. Might I start by assuming there must be a negative connection to water, which then uses seawater as conduit to the drive?
Newbie trying to learn and figure things out ?

 

[RichardS]

70 ohms before fault searching ?

OK, that is unlikely to be a simple short between two metals but might be something more involved. Could be even a switch or relay or other electric or electrical component?

Richard

 

[VicS]

70 ohms before fault searching ?

That could well be due to aconnection through the water.
It is lower than an approximate figure that I calculated for a connection via the cooling water intake. I reckoned that would be around 200 ohms or so.

Update:
This is getting stranger and stranger...
Down in boat this afternoon, and now there is no continuance between separated engine/gearbox(!) Assembled all elements, measuring for continuity for every operation. No continuity UNTIL I affixed the negative cables to the engine block.
So, it appears I have a negative problem. Might I start by assuming there must be a negative connection to water, which then uses seawater as conduit to the drive?
Newbie trying to learn and figure things out ?

Your sail drive is in contact with the water and a connection between DC negative and the water would not be unusual.
Therefore a connection between the engine and the sail drive with resistance of a few 10s of ohms through the water is no surprise.

If you do not have a direct connection between engine block and sail drive you do not have a problem. The insulating components which you have checked prevent that.

 

[PatrickSeb]

[QUOTE="VicS, post: 7715763, member: 1
If you do not have a direct connection between engine block and sail drive you do not have a problem. The insulating components which you have checked prevent that.
[/QUOTE]
Thanks for giving me hope for the dtary of next week's sailing holiday ? Tidird up my tools to enjoy a delf brewed IPA in the evenh dun ?

 

[PatrickSeb]

[QUOTE="VicS, post: 7715763, member: 1
If you do not have a direct connection between engine block and sail drive you do not have a problem. The insulating components which you have checked prevent that.

Thanks for giving me hope for the dtary of next week's sailing holiday ? Tidird up my tools to enjoy a delf brewed IPA in the evenh dun ?
[/QUOTE]
Need to start using my reading glasses ??