Common Rail Diesel as Replacement engine

[John Willis]

OK here comes a grenade into the pond of engine opinion.

I sail solo sometimes long distances (e.g. Guernsey to Vigo return) in my 1997 34' 8 ton yacht.

I have just had a Yanmar 3JH 40 CR (Common Rail) fitted to replace the old engine.

Anyone else done likewise or is considering doing so?

 

[Jmc1764]

Common rail has been around a while in cars so it should be as reliable as the standard diesel engine, and more efficient and cleaner. BUT with it comes all the electronics and can you diagnose and repair it yourself ?

 

[Topcat47]

While I've never had a problem with common rail diesels in motor vehicles (I'm on my fourth) I'm less sanguine when it comes to the marine environment. With old school mechanical injection, you might lose one injector/pump which would still permit running on two cylinders. you're ore likely to get one cylinder down on power that a complete failure. With an EMU you have a single point failure in a non-repairable (at sea) system. Unless you also carry substantial solar panels or a Secondary generator, this will rapidly leave you with no navigational aids or VHF as well. (says the man with a1GM10)

 

[Rappey]

For a mobo there could be fuel savings to be had.
For a sailing boat I'm not sure there are advantages ?
Electronic injectors and sensors could be the downfall of a good engine.
If the sensors fail the engine won't start.

 

[Sandy]

In my sailboat, I would not consider it at all. Far too complex to repair at sea, far too expensive to fix ashore.

 

[Arcady]

I have just had a Yanmar 3JH 40 CR (Common Rail) fitted to replace the old engine.

Anyone else done likewise or is considering doing so?

I have just specified the 4JH CR Yanmar and am entirely sanguine about it. Most of us seem happy enough to sail with a lot of other sophisticated electronics aboard (autopilot, GPS, radar, etc) without carrying spares, so why should the ECU on a common rail engine be any different? I suspect the working environment in a yacht engine compartment is probably far more benign than under the bonnet of a car.

 

[PaulRainbow]

The potential weak point isn't the electronics, they are housed in a nice warm, dry engine compartment, unlike a car where a lot of the electronics are under the bonnet. The biggest danger of catastrophic failure is the quality of the fuel. The high pressure circuit on a common rail diesel engine can be 2000 to 3000 bar. The tiniest particle of dirt or water can spell disaster. At those pressures dirt or water passing through an injector can score the injector, leading to severe mechanical damage. I've worked on common rail engines on boats where there have been five stages of filtration to ensure fuel quality at the engine.

 

[jwfrary]

The potential weak point isn't the electronics, they are housed in a nice warm, dry engine compartment, unlike a car where a lot of the electronics are under the bonnet. The biggest danger of catastrophic failure is the quality of the fuel. The high pressure circuit on a common rail diesel engine can be 2000 to 3000 bar. The tiniest particle of dirt or water can spell disaster. At those pressures dirt or water passing through an injector can score the injector, leading to severe mechanical damage. I've worked on common rail engines on boats where there have been five stages of filtration to ensure fuel quality at the engine.

as Paul says excellent filtration down to 2 microns is imperative to the longevity of the pump and injectors.

I would fit a fuel strainer like a racor 500 and stick a 10 micron in. The on engine filter will be 2 micron. Buy genuine or a quality manufacturer like Mann or fleet guard.

I haven’t any qualms about a CR engine on a yacht. Halbergrassy have been using them for years in their larger boats!

cleaner, quieter, more economical, and combustion chambers stay clean so longer life. Easy starting without pre heat. If your alt goes bad yes you could have lack of electric issues but most serious cruisers have enough solar to keep up for a while and if I was.going places further than that I would be carrying a spare anyway

 

[Laminar Flow]

My brother, a mechanical engineer by trade, used to work for Bosch. He has advised me never to install a common rail system in a boat, precisely because of the often dubious fuel quality and the need, as he put it, to service the fuel injection system in a virtually antiseptic environment.

 

[jwfrary]

as Paul says excellent filtration down to 2 microns is imperative to the longevity of the pump and injectors.

I would fit a fuel strainer like a racor 500 and stick a 10 micron in. The on engine filter will be 2 micron. Buy genuine or a quality manufacturer like Mann or fleet guard.

I haven’t any qualms about a CR engine on a yacht. Halbergrassy have been using them for years in their larger boats!

cleaner, quieter, more economical, and combustion chambers stay clean so longer life. Easy starting without pre heat. If your alt goes bad yes you could have lack of electric issues but most serious cruisers have enough solar to keep up for a while and if I was.going places further than that I would be carrying a spare anyway

i should add that I worked as an engineer on a fleet of commercial vessels all using CR and they never stopped due to a ecu failure. The only one that did stop turned out to be a faulty key switch! £150000 for the engine £2 for the key switch. Easy solve. Fleet wide there’s now no key!

in fact the ecu control, often saves the engine from what could otherwise be a catastrophic failure. So in many ways it’s a good thing.

but you do have to be considerably more careful with the fuel cleanliness.

 

[pcatterall]

We would opt for an old fashioned replacement for simplicities sake. Are common rail inherently more efficient considering that marine engines typically run at a constant cruising speed?

 

[Roberto]

Distant shores maybe what happened to a crew with one lf those engines in Brazil: the engine "sensed" there was something wrong with local fuel and would shut itself off; they were very happy to have a few jerricans left with fuel bought in Europe as they used it to "fool" the engine and start it, then they reverted to local fuel for an hour or so until the engine stopped again, re-start it from the jerricans and switch to local fuel until the engine stopped again, and so on. Next to a nightmare.

 

[Skylark]

My nephew has a mate who delivers newspapers to a guy whose uncle used to work in the canteen for an engine manufacturer and he offered this advice : ignore the dinosaurs.

Prudent preparation is always wise before putting to sea. If your boat had a Ruston & Hornsby hot bulb engine you'd check it and its systems before a Biscay crossing.

 

[Bobc]

Replaced my engine 2 years ago with a fully mechanical Beta, and would do the same again without question.

 

[Graham376]

Common rail diesels have been around for many years, how many amateurs can fix their cars in a nice dry garage when something goes wrong and ecu shuts them down? Can't even change an injector without recoding, even the more basic Volvo black boxes have regular problems. On a single engine boat, I want something I can fix, quite happy to strip down and rebuild old tech engines but I wouldn't buy a boat with common rail engine.

 

[earlybird]

AFAIK, common-rail engines require extremely good fuel filtration to preserve the injectors and HP pumps. That doesn't sit well with the fuel systems in many yachts.

 

[Bilgediver]

My three legged Doxford with engine driven pumps was a common rail engine and built in 1944 . All sorts of we cams and tappets to control both start and end of injection so no problem getting balanced Indicator Diagrams. Not a valve or transister in sight. 3000 HP

 

[lynallbel]

It will need top quality filtration, dirt and water will spell expensive trouble, no old slop, no old ratty containers for transferring fuel.
Quite a few trucks suffer from common rail issues, all down to sub sttandard filtration, and sub standard servicing of the fuel system.

 

[Caraway]

AFAIK, common-rail engines require extremely good fuel filtration to preserve the injectors and HP pumps. That doesn't sit well with the fuel systems in many yachts.

This may have already been touched on in this thread.

 

[jwfrary]

We would opt for an old fashioned replacement for simplicities sake. Are common rail inherently more efficient considering that marine engines typically run at a constant cruising speed?

Common rail and its higher injection pressures results in a cleaner burn and less wasted fuel and therefore better efficiency's. Doesn't matter that they are fixed or variable in speed the advantage remains.