Petrol and Diesel Cars on a Ferry

jayok

I've seen this before on a ferry crossing and I am not sure why. But the leaflet they give you when you board states something like:

Petrol Cars: Apply the handbrake and leave in gear
Diesel Cars: Apply the handbrake but do not leave in gear

I can understand the need to leave the cars in gear in case the ship rolls and the handbrake fails, but why not for diesels?

peasant

Because, given a minor electrical fault (fuel cut-off solenoid not working), a diesel engine could be jolted into running by the ships motion if left in gear.

biko

A diesel has a compression combustion engine and could in theory start up by rolling back and forth. Not sure if this has ever happened to anyone though.

JHMEG

Cos diesels are untrustworthy.

jayok

Really? With the amount of prep work done by various circuits and systems to get a diesel going I wouldn't have thought it could roll start without the ECU firing this up?

Surely a failed handbrake is a greater risk?

peasant

Magnus wrote: »

A diesel has a compression combustion engine and could in theory start up by rolling back and forth. Not sure if this has ever happened to anyone though.

I've managed to start my 3.5 ton motorhome (with an empty battery) rolling down a very gentle slope for only a meter or two at just about walking speed ...so it is possible, once the fuel supply isn't cut off as it normally would be when parked

jayok

JHMEG wrote: »

Cos diesels are untrustworthy.

That's just your general dislike of diesels - isn't it?

dunleakelleher

JHMEG wrote: »

Cos diesels are untrustworthy.

that's why every long running commercial engine from taxis to trucks to ships runs on diesels. even the last le mans (ya know the 24 hour endurance race) was a diesel.;)

jayok

peasant wrote: »

I've managed to start my 3.5 ton motorhome (with an empty battery) rolling down a very gentle slope for only a meter or two at just about walking speed ...so it is possible, once the fuel supply isn't cut off as it normally would be when parked

Wow, I always imagined it was much harder to get diesels going than that. So from no heater-coils, etc 1-2 meters and you're off? I assume the coils just make the engine easier to start and place less demands on the starter motor?

JHMEG

jayok wrote: »

That's just your general dislike of diesels - isn't it?

No, it was a joke.

JHMEG

dunleakelleher wrote: »

that's why every long running commercial engine from taxis to trucks to ships runs on diesels. even the last le mans (ya know the 24 hour endurance race) was a diesel.;)

That's really to do with economy. Every litre of diesel contains more stored energy than more refined fuels like petrol or ethanol.

JHMEG

jayok wrote: »

Wow, I always imagined it was much harder to get diesels going than that.

Diesels will run on their own engine oil if it starts to leak into the cylinders. I've seen a Transit do it down the country, and someone posted pics here a few years ago of a Laguna that did it. The will run till they have burnt all the oil and the engine literally grinds to a halt.

It's a known "feature" with diesels.

peasant

jayok wrote: »

Wow, I always imagined it was much harder to get diesels going than that. So from no heater-coils, etc 1-2 meters and you're off? I assume the coils just make the engine easier to start and place less demands on the starter motor?

The engine in question is direct injection, now glow plugs ...and it's so old that it has no fancy electronics either, just a mechanical injection pump.
The battery had enough volts left to open the fuel solenoid ...a gentle push and you're away

jayok

peasant wrote: »

The engine in question is direct injection, now glow plugs ...and it's so old that it has no fancy electronics either, just a mechanical injection pump.
The battery had enough volts left to open the fuel solenoid ...a gentle push and you're away

Brilliant. I can imagine the feeling of delight from this roll start once it fired!

peasant

JHMEG wrote: »

Diesels will run on their own engine oil if it starts to leak into the cylinders.

What's that got to do with ferries?

jayok

JHMEG wrote: »

Diesels will run on their own engine oil if it starts to leak into the cylinders. I've seen a Transit do it down the country, and someone posted pics here a few years ago of a Laguna that did it. The will run till they have burnt all the oil and the engine literally grinds to a halt.

It's a known "feature" with diesels.

So like the pigs of the farm then. Will eat anything, smelly, grunt a lot, questionable emissions, but will generally keep going!

peasant

jayok wrote: »

Brilliant. I can imagine the feeling of delight from this roll start once it fired!

Relief ...not just delight. Arsehole of nowhere, empty battery, no phone reception and the slope wasn't very long either.:D

JHMEG

peasant wrote: »

What's that got to do with ferries?

About as much as your 3.5 tonne motorhome, maybe, or that diesels don't need fuel to run.

mickdw

In fairness, there is not a hope of a modern diesel starting without ignition being on & powered. Old stuff could very well start if there was a solenoid fault etc so I guess that is where the rule came from.

Marlow

It's most likely back from older type of Diesels, that didn't need much electronics.

If the engine on a old diesel car is warm and the car is in gear, it could start very easily, as it doesn't need ignition to run.

Modern diesels are very much depending on electronic components, like the ECU, electronic injectors etc., so chances are minimal, if at all possible, that the engine could start in that scenario.

/M

peasant

Marlow wrote: »

If the engine on a old diesel car is warm and the car is in gear, it could start very easily, as it doesn't need ignition to run.

Even an old engine still needs "ignition" to run ...well it needs power on the electric solenoid valve to open the fuel supply. The ignition key turns that on and off.

Some people however bypass this valve when it's broken (stopping the engine by stalling it) and in that case a simple jolt could theoretically start the engine in gear.

zilog_jones

Marlow wrote: »

Modern diesels are very much depending on electronic components, like the ECU, electronic injectors etc., so chances are minimal, if at all possible, that the engine could start in that scenario.

Don't forget immobilizers too