Engine problem

[Happy sailir]

Hi, I am new to the forum and I come looking for helpful advice
We own a beneteau Oceania 361 with a Volvo md2030 engine. Currently if the engine has been run for a few hours then stopped it will not restart.....this has lead to a couple of very hairy scary moments at sea. In order to fix the problem over the course of the season the following things have been done
Replaced...the panel switch the wire from panel to solenoid, the solenoid itself. The starter motor has been removed checked and found to be ok. We have replaced the engine control box and relays in it and we have renewed all the battery terminals!!
Still after motoring for a couple of hours when it is stopped the engine wont restart.
We have fitted an emergency button to allow us to bypass everything and effectively just connect battery to starter motor...this does allow engine to start even when hot.
Any ideas on what we may have missed?
This situation is starting to mean I am not living upto my name....which should really read...happy sailor!!!!
I hope I have posted this inn the correct place if not perhaps you could redirect me thanks

[hpeer]

Weird. What a PITA.

What you describe sounds like a heat related fault. You did not describe under what conditions the engine does restart. That would be an automatically resetting circuit breaker that will trip when hot but auto reset when it cools down sufficiently.

Circuit breakers come in 3 types:

Type 1 are auto resettable, and once tripped, will attempt to reset the circuit, or ‘cycle’, as the internal elements of the breaker cool down.
Type 2 (trip and hold) are called modified reset, and will remain tripped until the power is removed from the breaker.
Type 3 circuit breakers are manual resettable, and require that a button or lever be pushed in order to reset the breaker.

https://www.grote.com/questions/hell...-one-act-like/

Have you run a temporary wire from the battery to the panel switch or checked for power on the switch while the engine is refusing to start?

Have you tested this without running the engine? In other words do this:
1. Start engine
2. Shut engine down but leave key in ON position for a couple of hours
3. Then try to start engine

If you then have the same problem you know it’s not related to engine heat.

Yeah, it sounds dumb, but I am groping for a cause.

[Spot]

How long is the engine sitting between running and not starting? Does it ever have trouble from a fully cold (overnight) condition?

If the starter works after being jumped, it would seem to be something between the ignition key and the starter that is failing more than the starter.

A breaker could act like that, not taking the load of a warm or hot start. Or it could be a bad relay, or a circuit board with a cracked conductor or solder joint.

I am not a Volvo mechanic. I did just go through this with a motorcycle, cracked solder joint on the circuit board where the starting relays reside. Two minutes with solder and iron and the issue was solved...except for the gummed up carbs from sitting too long without starting.

[tkeithlu]

You have partially traced it down by bypassing the solenoid with your emergency switch and heavy wire from the battery. Get the situation hot at the dock, and work backwards. each time add one more element to the circuit. Battery directly to solenoid? Battery directly to circuit breaker? Battery directly to key switch? You're going to find a failure here, or you're in the terrible situation of a non-replicable failure.

[Happy sailir]

Many thanks for the replies so far.....we will try and work through the suggestions. When we replaced the engine control box, Volvo Greece wanted to sell it to us with the wiring loom. We opted instead to just have the control box......this may have been our mistake.
While the most obvious conclusion is that the problem appears to be heat related, there have been one or two occasions when it hasn't started when cold....exceedingly frustrating.

[NYSail]

So your bypass button will start it?? I assume that basically jumps the wires at the starter just like an old fashion screw driver bypass. If so like was said you have a heat related issue upstream.....

Good luck
Greg

[Emmalina]

Engine will have more compression when hot so I would imagine this is an electrical issue.

[crashley]

when you say the engine wont start what actually happens
are you actually bypassing the solenoid or bypassing the key start system
ie does the panel light up does the solenoid click etc
you need to start at one end and work through to the other
I would measure for volts at the solenoid on the starter motor if it is getting 12volts then move backwards through the system to the key or starter button
it may be in the gearbox in gear start inhibit system

[Bruce K]

As Crashley says, it sounds like the start in gear inhibit, when engine does not start, try pulling gear lever into gear then out to rev a few times, then try to start, inhibit switch sometimes gets sticky or needs adjustment.

[GordMay]

Greetings and welcome aboard the CF, Happy.

[Captain Graham]

Just to make sure I understand
1. Then the motor is cold you can start the motor.
2. Then the motor is hot (or has been running for a few hours) and you turn off the motor, the motor will not re-start.

Questions
When you say it will not re-start what do you mean?
Does the started motor fail to turn over?
Does the started motor turn over but the diesel motor does not start?

It the problem is the started motor does not turn over when the engine has been running for a few hours (hot) then look for the problem in the wiring to the started motor.
It may be that a wire going to the starter has a crack in the conductor and when it gets hot the crack opens.

[Happy sailir]

We have sent this to the electrician working to help us, hopefully this might prove to be the problem

[Captain Graham]

[QUOTE=Happy sailir;2952263]We have sent this to the electrician working to help us, hopefully this might prove to be the problem[/QUOTE

When you find the problem please post it so we can all learn.
Thanks in advance.

[RaymondR]

Originally Posted by Emmalina

Engine will have more compression when hot so I would imagine this is an electrical issue.

Don't know about that.

Cold oil is generally a lot more viscous than hot and if cylinder glazing and consequent lack of compression is the problem might explain why the engine will not start when hot. Faster cranking might then compensate for the lack of compression which is related to air leakage past the piston rings.

[Emmalina]

Originally Posted by RaymondR

Don't know about that.

Cold oil is generally a lot more viscous than hot and if cylinder glazing and consequent lack of compression is the problem might explain why the engine will not start when hot. Faster cranking might then compensate for the lack of compression which is related to air leakage past the piston rings.

Metal expands ! Oil is just lubricant ! Seen this problem on a few boats with sad batteries.