AD41p-A wont start

[Sailorsam101]

Another lovely hot day today and the bloody boat won't start of course!!!

Started both engines and all well...30 mins later the port engine just clicks as if the battery was flat.

Both batteries on that engine are new and fully charged..i checked. So called out Sea Start.

What we/he found was this....

Put a battery pack to the starter motor direct and earth on the engine and it starts form the key first time...so no mechanical issues with the starter motor of relays etc.

Check voltage to start motor and it's 13v..all good there...try starting and it drops to nothing. Check the batteries when trying to start and no voltage drop there at all!!!

Remove starter cable from battery and add a jump pack direct onto it...engine turns over but does not start...jump leads were not good.

Check battery isolater switch to port engine is working and it is.

Check all connections end to end on the cable and no issues found anywhere.


So where we are no is that there is a fault somewhere in the cable that goes from the battery to the isolater and then onto the starter motor...maybe. But we got it to turn over as said above when using this cable.

Next plan is to get a cable direct from the battery to the start motor and see what happens, Are you still following me?..any ideas?

Anybody recommend any good electrical bods on the hamble please?

Cheers

 

[BruceK]

what test did you use to determine the isolator is ok?

 

[Montemar]

There is a high resistance between battery and starter somewhere you just have to find it. Connections seem most likely then possible cable damage.

 

[Momac]

Faulty battery isolator switch?
Faulty starter relay, o faulty connection to the relay - is this in a black box on top of this engine

 

[Gemini]

Don't put a direction to from battery to starter motor, unless you have an isolator switch in the circuit, large currents will start to flow as soon as you touch the battery terminals.

Try Volvopaul from this Forum

 

[aquatom]

How have you tested the battery isolator? Try connecting both cables to the same terminal on the back of the isolator.

 

[Sailorsam101]

Just went to the boat to have another look at this. I bought a long heavy duty jump cable set as i want to prove or rule out the existing cables.

Connected one end of the jump to the positive on the starter and the other to the battery...thus bypassing the existing cables....and nothing..just clicking again!

So it's not a power input issue. All connectors on the positive side have be checked and tested without issue.

This leaves either some hidden relay that i can't find or a negative or ground issue. Any ideas folks?

Cheers

 

[Sailorsam101]

Right then..so i connected the engine block direct to the negative on the battery and i can now start then engine fine on the key.

So this means that I've got a bad earth on it somewhere as previously suggested.

But I've searched and i cann't fond any place where the block earths or returns to the battery....any ideas please before i get somebody in!

Thanks

 

[Rob the boater]

Right then..so i connected the engine block direct to the negative on the battery and i can now start then engine fine on the key.

So this means that I've got a bad earth on it somewhere as previously suggested.

But I've searched and i cann't fond any place where the block earths or returns to the battery....any ideas please before i get somebody in!

Thanks

Hi

I assume you’ve traced the neg lead from the battery to one engine block and it’s connected cleanly

Does one engine start ok and the other not (I haven’t re read the whole post) ?

Have you got a link from the battery to one engine and then a large link between to the second engine - this could be missing / corroded off

So I would put a negative jump lead from one engine block or good bare metal plate to the other any see what happens then

If it works with a direct jump lead neg it can only really be a large size cable problem not relays etc

My money would be on a link at the back end of the engines that you can’t easily see having broken off

Rob

 

[Sailorsam101]

Yes i think you are right. But i can't see where the black wire attaches to the engine block...just can't find anything and can't get in to trace the cable fully...of course it was all put in before the engines were installed!!!!

 

[Rob the boater]

I’d guess Right at the back on the bell housing above the leg coolant pipe under the turbo charge coolers
I would expect it near the starter motors

Not idea as you’d have aloose cable but disconnect existing link from battery to the unknown point A new link in
Make safe the cable taken off the battery

 

[Rob the boater]

*put a new link in predicted text don’t u just love it

 

[Sailorsam101]

After much sweating this morning i found the earth from the port engine...it's under the Turbo and hard to see.

What i didn't expect is that its a cable straight to the stbd engine and then another cable off back into the boat somewhere.

I undid and remade the earth connection on the port engine and then tested it...hey presto it fired into life on the key. But tried a second time and no joy.

So it looks like this earth cable has had it. Took it off and can't find a fault but having another made so i hope it solves it....it can't be anything else causing it.

but what i don't understand is how such thick cable can just fail..

 

[Kawasaki]

'Thick cables' Can fail
On boats like yours there is something called a 'reverse earth' unlike cars etc
We have no chassis made of steel etc to 'ground' on, therefore making a more difficult to create an electrical 'flow' as it where
I am no Expert on this but A Man told me once!
I came across it once helping a fellow Forumite who's outboard would not start
The main 'Thick Cable' from the Control box to the engine was very thick but was fooked
Renewed it and all was ok
Like You, at first I could not believe that the 'thick cable' would have caused the snag
The salty/briny enviroment we play in really does play havoc with copper core type wiring
That a no brainer!
I think you have cracked the problem basically
Good Luck and all who sail in Her
:encouragement:

 

[Rob the boater]

After much sweating this morning i found the earth from the port engine...it's under the Turbo and hard to see.

What i didn't expect is that its a cable straight to the stbd engine and then another cable off back into the boat somewhere.

I undid and remade the earth connection on the port engine and then tested it...hey presto it fired into life on the key. But tried a second time and no joy.

So it looks like this earth cable has had it. Took it off and can't find a fault but having another made so i hope it solves it....it can't be anything else causing it.

but what i don't understand is how such thick cable can just fail..

Just to clarify.

A Fat Cable links from port engine to starboard engine

Another fat cable runs from the starboard back in to the boat somewhere

Have you seen where the cable from the battery goes to ?

The cable back in to the boat could be running domestic systems as an outgoing negative or a link to the leg lift pump (assuming your on out drives)

The battery to engine cable could still have a bad connection which you disturbed with out realising it.

After the heavy current went through and started the engine it’s possible if it’s a bad connection it may have become high resistance again hence the problems back

Copper cables where exposed to air and water appear green and become poor conductors at the crimp / lug ends which some times creep up inside the insulation

 

[Sailorsam101]

Good points you make. The cable form the engines is large and black...the same thickness as a battery cable so lets assume it is the engine earht as i can't find anything else on the engine that is that big.

It goes from the port to a bolt on the stb bell housing in one cable...then another cable using the same bolt on the stb engine goes forward and disappears under my battery box and forward into the boat. Without taking lots of stuff apart i can't see where it goes.

The negative from the battery goes forward into the boat and again into a black hole that i've no idea where it ends up.

I can't prove it but the battery cable and earth from the engines sort of go into the same black hole under the drivers seat.

What i do know is that i have 100% proven that its the earth to the port engine that is at fault and this cable is the only thing left to check and change as the stbd earth is just fine....and just to clarify all three batteries are linked to a common negative...not sure if that's right but its worked for years like that.

Once i get the new cable made i will cut open the old and see what going on inside..its 15 years and has been underwater before so i'm hoping that's the issue as if not i'm stuck for ideas!

 

[Rob the boater]

Good points you make. The cable form the engines is large and black...the same thickness as a battery cable so lets assume it is the engine earht as i can't find anything else on the engine that is that big.

It goes from the port to a bolt on the stb bell housing in one cable...then another cable using the same bolt on the stb engine goes forward and disappears under my battery box and forward into the boat. Without taking lots of stuff apart i can't see where it goes.

The negative from the battery goes forward into the boat and again into a black hole that i've no idea where it ends up.

I can't prove it but the battery cable and earth from the engines sort of go into the same black hole under the drivers seat.

What i do know is that i have 100% proven that its the earth to the port engine that is at fault and this cable is the only thing left to check and change as the stbd earth is just fine....and just to clarify all three batteries are linked to a common negative...not sure if that's right but its worked for years like that.

Once i get the new cable made i will cut open the old and see what going on inside..its 15 years and has been underwater before so i'm hoping that's the issue as if not i'm stuck for ideas!

One thing that’s just popped in to me head - just check you haven’t got a isolated earth type starter motor Meaning it’s got a direct positive from battery to the solenoid and a separate earth from the engine block to a separate negative terminal on the starter
This negative won’t be on the solenoid unlikely but possible.

From where you at it would seem the link between the engines is the issue

 

[Rob the boater]

One thing that’s just popped in to me head - just check you haven’t got a isolated earth type starter motor Meaning it’s got a direct positive from battery to the solenoid and a separate earth from the engine block to a separate negative terminal on the starter
This negative won’t be on the solenoid unlikely but possible.

From where you at it would seem the link between the engines is the issue

Like this

https://www.google.co.uk/search?cli...i71j0i22i30.TkjfNykd_os#imgrc=cNi8qHczlgcsRM:

 

[Rob the boater]

Like this

https://www.google.co.uk/search?cli...i71j0i22i30.TkjfNykd_os#imgrc=cNi8qHczlgcsRM:

Or this even as the links been cut short

https://www.marinepartseurope.com/en/volvo-penta-explodedview-7742700-30-1876.aspx

 

[Sailorsam101]

Yes i've got the bonding wire and checked it and it's fine.

But it can't that by the way i can fire it up on the key linking the block to the negative terminal directly. So can't be anything linked to the starter.

But cheers for having a think.

it is a strange and confusing fault but i've gone over it bit by bit and it can only be this cable that's at fault. Either way i'll know on Friday.