was awoken by my inboard diesel self-starting!

[uldinch]

Ahoy is in order! Wrong season entirely to complain abt my Volvo Penta MD2020 repeatedly trying to self-start. Replacing the relay boxes did not help. Apart from hoisting the engine out there is limited access - cannot check the relay sockets by lifting them sufficiently to examine their underside and leads for signs of discoloration and/or charring. No tech counsel available in my Pacific island and I simplified the control panel to introduce 2 switches to bypass the original key switch along w rev meter and the 4 alarms. THE Q.: Am I obsolete to assume diesel does not need battery supply once it is firing? I would welcome your kind feedback and not experiment by either pulling glow and starter relays out after engine is on or swithing off battery supply; I hate to think of the scenario with starter attempting to self-start on a working diesel! Thanx immensely and a deservedly fine 2023 to all!

[goat]

Older diesels can run with the key off or battery disconnected. They just can't start without battery power or a hand crank. Sounds like you've got power going to your solenoid somehow.

goat

[Stu Jackson]

Or it could be a short in your wiring harness (cockpit panel to engine).

[hpeer]

Above are correct.

Consider the start sequence.

1 turn key to apply power to solenoid
2 solenoid engages
3 this applies house battery to starter
Starter spins

Very simple solution is to cut solenoids control wire, or disconnect from solenoids.

Then, to start, replace control wire.

Alternative, run control wire through a switch, open switch solenoid can not operate, close switch to allow starting.

This is not a trivial problem if the solenoid were to try to engage while the engine was running bad things might happen.

Then try to find a new starter switch. That is likely the culprit.

[jamhass]

If a fixed-blade prop spins the engine while sailing, it is possible for the engine to start. Thus, keeping the tranny in neutral might be a solution. If at anchor, was there a significant current perhaps causing the prop to spin the engine?

[ScottRhodes13]

Originally Posted by uldinch

I would welcome your kind feedback and not experiment by either pulling glow and starter relays out after engine is on or swithing off battery supply

Be careful shutting off the battery while the engine is running. This can ruin the alternator.

[rwidman]

A battery switch between the starting battery positive cable and the engine would prevent it from starting by itself.

That's not a "fix", but it would avoid the problem until you can troubleshoot.