Kad300 not starting intermittently

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Iwilliams0511

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Looking for some advice and things to check next.
Boat is a Windy Khamsin 34 with twin KAD300's
Port engine is fine. Sometimes very intermittently the starboard engine will not start or even get to station. So holding the key symbol on pad the starboard engine will not click on. No light!
I have tried the following
Swapping ignition barrels
Cleaned all connections on Volvo loom in engine bay
Cleaned multi pin plugs into ECU
Swapped cables on key pad port to starboard.
I left it over winter for 3 months started first time. Just put it back in water after 3 weeks out and it has done it again!
Any ideas what to check next?
 
everything you just did plus:
all the battery connections from the battery to the engine connections.
have you gone through the connections inside the little fuse box and checked/swapped the relays?
 
another idea
check the DC to DC converter in the fuse box. With a voltmeter measure the input voltage and the output voltages - while not running and during cranking.
They can start to fail and go intermittent. If in doubt about it's reliability swap it with the one in the other engine and see if the problem moves.
 
kashurst said:
another idea
check the DC to DC converter in the fuse box. With a voltmeter measure the input voltage and the output voltages - while not running and during cranking.
They can start to fail and go intermittent. If in doubt about it's reliability swap it with the one in the other engine and see if the problem moves.
Click to expand...

kashurst said:
everything you just did plus:
all the battery connections from the battery to the engine connections.
have you gone through the connections inside the little fuse box and checked/swapped the relays?
Click to expand...
If that is the one on top the engine then yes swapped all fuses and relays!
 
Iwilliams0511 said:
Funny you say that, the anodes on this engine/leg were worn really badly this year.
Where is the main earth? Is it from battery to starter?
Click to expand...
The earth point on the engine depends on the boat. Some manufacturers run a separate cable from the battery negative to each engine. Some run just one and have a link cable across to the other engine. Actually take each engine connection off completely and clean it before refitting it. Do the same all the way back to the batteries.

The KA(M)D engines being electronically controlled can be suddenly a bit picky if the voltage on ignition/start drops too low, which can be caused by resistance in the big battery cable connections. It will probably measure all OK with a multimeter but stick 150 amps through it and suddenly it's not OK. Pretty sure the ECU measures the supply voltage and if it's not happy it won't start. Volvo added the DC to DC converter to partially eliminate start up volt drops caused by either old batteries and/or poor connections.

If your anodes are wearing unusually fast that's a different problem.
 
kashurst said:
The earth point on the engine depends on the boat. Some manufacturers run a separate cable from the battery negative to each engine. Some run just one and have a link cable across to the other engine. Actually take each engine connection off completely and clean it before refitting it. Do the same all the way back to the batteries.

The KA(M)D engines being electronically controlled can be suddenly a bit picky if the voltage on ignition/start drops too low, which can be caused by resistance in the big battery cable connections. It will probably measure all OK with a multimeter but stick 150 amps through it and suddenly it's not OK. Pretty sure the ECU measures the supply voltage and if it's not happy it won't start. Volvo added the DC to DC converter to partially eliminate start up volt drops caused by either old batteries and/or poor connections.

If your anodes are wearing unusually fast that's a different problem.
Click to expand...
Thank you, I will start tracing cables and start cleaning all the terminals
 
Finally got to the boat to do some fault finding and kashurst thank you
It is the DC - DC convertor!
Can you bypass this temporarily?
Also where is the best place to get another unit?
Costs seem to be very high!!!
 
Iwilliams0511 said:
Finally got to the boat to do some fault finding and kashurst thank you
It is the DC - DC convertor!
Can you bypass this temporarily?
Also where is the best place to get another unit?
Costs seem to be very high!!!
Click to expand...
Well done finding the cause.
Yes you can bypass it temporarily - really emergency use only rather than do a summer on it. And only if your batteries are in good condition. It's there for a reason it protects the ECU which is seriously expensive. It is a volvo specific bit of kit so your best bet is to phone around the usual Volvo marine suppliers. Brace yourself, I paid about £300 for one about 6 years ago. I tried finding a suitable alternative DC to DC convertor but it has quite unusual characteristics and there is always the niggling doubt about protecting the ECU.
Costs seem vey high! It could be worse, it could be a Yanmar part. ;-)
 
kashurst said:
Well done finding the cause.
Yes you can bypass it temporarily - really emergency use only rather than do a summer on it. And only if your batteries are in good condition. It's there for a reason it protects the ECU which is seriously expensive. It is a volvo specific bit of kit so your best bet is to phone around the usual Volvo marine suppliers. Brace yourself, I paid about £300 for one about 6 years ago. I tried finding a suitable alternative DC to DC convertor but it has quite unusual characteristics and there is always the niggling doubt about protecting the ECU.
Costs seem vey high! It could be worse, it could be a Yanmar part. ;-)
Click to expand...
Thank you
This unit only has to hold the voltage stable during cranking so I can't see why it can't be any DC to DC converter that gives a stable 12v output?
Currently the price of a genuine part is over £900
 
Iwilliams0511 said:
Thank you
This unit only has to hold the voltage stable during cranking so I can't see why it can't be any DC to DC converter that gives a stable 12v output?
Currently the price of a genuine part is over £900
Click to expand...
£900!!!!!
strewth. have you tried any european suppliers?
 
kashurst said:
£900!!!!!
strewth. have you tried any european suppliers?
Click to expand...
Need to take a look, but am thinking of trying an after market DC to DC converter as all it is doing is holding a steady output.
The input voltage was 12.4 v and output was 12.06 V of the good unit. So I'm sure an after market unit would be okay
 
Iwilliams0511 said:
Need to take a look, but am thinking of trying an after market DC to DC converter as all it is doing is holding a steady output.
The input voltage was 12.4 v and output was 12.06 V of the good unit. So I'm sure an after market unit would be okay
Click to expand...
£900 ouch! As @kashurst said, they used to be £300.

What I can't understand is that the DC/DC box seems to have 5 wires going in/out of it. Anyone got a wiring diagram?
 
Iwilliams0511 said:
I have been thinking about trying one of these units but set to power supply mode.

https://www.victronenergy.com/dc-dc-converters/orion-xs-dc-dc-battery-chargers
Click to expand...
That looks like it would work. I do have a bit of a reservation in that it has multifunctionality and that is set up in software. You don't want it deciding one day that it is now a battery charger instead of a power supply. On boats I always work on the premise that if it can go wrong, sooner or later it will. Probably just me being paranoid.
Is there a basic DC to DC converter available that cannot change function?
 
petem said:
£900 ouch! As @kashurst said, they used to be £300.

What I can't understand is that the DC/DC box seems to have 5 wires going in/out of it. Anyone got a wiring diagram?
Click to expand...
Remote voltage sense (i.e. at the load end of the wire to compensate for voltage drop in the cable from the regulator to the load)?
 
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