Common Rail Diesels - Experience

[BrightAyes]

I am considering repowering my sail boat which has a Yanmar 4JH3-TE diesel. I note all the new engines are computor controled common rail injection.
It appears some of these engines have been in service for about 5 years and I am wondering about the reliability of these engines. Any wisdom?

[ranger58sb]

They've been around longer than that, although maybe not so much in smaller engines like for your application.

Better fuel economy, which might not matter for you... given you might not spend much fuel anyway... and "better" might be a small word, too.

Cleaner.

Very reliable except... they're also electrically controlled... which means if you have an electrical glitch, the engine might stop. And no restart until the electrical problem gets fixed.

If you're a data junkie, they can often tell you everything you need to know about the engine, perhaps even the planet, what you had for breakfast, etc.

Not inexpensive.

Why do you want to repower?

-Chris

[RaymondR]

Don't do it.

There are few complex mechanical devices more reliable than the older diesel engines with entirely mechanical fuel systems and with the engine in a boat if you really need the engine you really need it.

[goboatingnow]

Because of emmisions and the quest for fuel economy every engine will have a ECU , they are as reliable as the base engine , if you have concerns simply carry a spare ECU.

[Scubaseas]

You can still get Yanmars without common rail. 4JH4 TE for example. From my auto/truck experience common rails are fine as long as the fuel is super clean. Better fuel economy and lower emissions by virtue of being able to adjust things in real time but there are more and expensive parts involved to do this. Like a exhaust gas sensor and an ECU.

For a boat I'd go with a non common rail. Much easier to get fixed by you or the mechanic you hire. One problem with an ECU is you need another ECU to talk to it. Like a scan tool. Probably a proprietary one available only to Yanmar dealers at great cost. Limits you to who can diagnose and fix it.

[RaymondR]

I coastal cruise my 40' sail boat for 7-8 months of the year and burn 200-300 litres of diesel each year. Would the slight increment of extra air pollution I cause justify my old style mechanical fuel injection being replaced by a modern, electronically complex, common rail diesel?

[Scubaseas]

Originally Posted by goboatingnow

Because of emmisions and the quest for fuel economy every engine will have a ECU , they are as reliable as the base engine , if you have concerns simply carry a spare ECU.

I'd make sure the ECU was plug and play before buying one. Might be. Might not. Almost every car and truck and off road ECU has to be coded to the vehicle. Most have an idle adjustment or "learn" process which often involves a scan tool of some kind

[NBs]

hi, i have a trawler single cummins common rail, i have been driving it for over 3000 hours and the only repair was the sherwodin water pump">raw water pump which is known to fail (design failure).

The best thing about a common rail is that you can run with a small load of problems with carbon, glazing in the cylinder, etc. because they can adjust the fuel so precisely and it burns optimally.

The fuel must be good, as must other diesels. Good pre-filtration Racor aqua block filter 10micron and water separator and 2 micron filter in the engine, that's all and you get clean diesel.

I know the same machine as I have in a few boats has run over 20,000 hours of normal maintenance, even the turbos are ok. People are afraid of everything new, the common rail has not proven to be worse than old time diesels.

NBs

[zstine]

Volvo had a huge issue with bad ECU's. I know several people who were stuck in remote areas for months, some of which went through multiple ECUs in short order. I heard the issue is fixed now..idk?

Beta marine and others still sell old dumb engines. I too don't like the ECU, but it is the future. As others have said, carry a spare ECU if you have one.

[zstine]

Originally Posted by RaymondR

I coastal cruise my 40' sail boat for 7-8 months of the year and burn 200-300 litres of diesel each year. Would the slight increment of extra air pollution I cause justify my old style mechanical fuel injection being replaced by a modern, electronically complex, common rail diesel?

It's not just you RaymondR. It's the thousands of other boaters too. Every person makes a small difference and we all need to work together... ah **** it! Screw the kids, burn your dirty oil!

[IOM]

There is absolutely no doubt common rail is a better engine, cleaner burning, more power you can add to the list I'm sure.
As long as you stay near to a good part source , and your engine room is as dry as the desert, you will be fine.
If you can't be 100% sure of the diesel quality , or have water in the bilges, or going to remote places, then perhaps a rethink is in order.


And just for entertainment, call the spares guys, and ask what the old engine injectors, pumps, etc cost....then call the emergency services and while they on the way call the spares guys and ask what the common rail pump, injectors, ecu, pressure sensors, mass air flow etc cost. And even you carry the spares with you, you will in all probability need a diagnostic machine to enable the parts once installed

[NBs]

Originally Posted by IOM

There is absolutely no doubt common rail is a better engine, cleaner burning, more power you can add to the list I'm sure.
As long as you stay near to a good part source , and your engine room is as dry as the desert, you will be fine.
If you can't be 100% sure of the diesel quality , or have water in the bilges, or going to remote places, then perhaps a rethink is in order.


And just for entertainment, call the spares guys, and ask what the old engine injectors, pumps, etc cost....then call the emergency services and while they on the way call the spares guys and ask what the common rail pump, injectors, ecu, pressure sensors, mass air flow etc cost. And even you carry the spares with you, you will in all probability need a diagnostic machine to enable the parts once installed

You're right, old diesels are heavily built and last a long time, fueling almost any combustible liquid from a cooked fat seal. here is a good example

https://youtu.be/GCpJF8QUf1Q

some hot bulb diesels are still in use ... the video is from a small machine and these can be found bigger if needed.

Nbs

[Searles]

Common rail diesels are verry old most Detroit 2 strokes are common rain ,has nothing to do with ecu s Cummins diesels 4 strokes are mostly common rail ,no ecus manically injected ,electronic pulse injection ,use ecus for precision timing,have lots of trouble with small mercruiser ecus also a number of Volvo units ,the older style diesel mechanic can do nothing when they stop ,or why .��⛵️⚓️

[Barkingmad]

No personal experience in boats but in farming and construction FAR fewer problems with the old school dumb diesels. This is where $'s hit the road so to speak.

You're pretty much SOL trying to repair a newer John Deere farm tractor on your own without the JD factory tech only scan software, think there may be a class action lawsuit about that...
I'll rebuild before I stick one of those things in my boat.

Plus the rebuild of an existing engine is PROVEN to be far more environmentally friendly than production a brand new engine. Gotta go a LOOOOOOONG way before you recoup those emissions from the entire production process beginning with mining ore to shipping the finished product.

[Scubaseas]

In the things with wheels world ECU failures were often caused by voltage supply issues. Like jump starting the car with the key on and reversed polarity on the jumper cables.

How reliable are ECUs and other sensitive electronics? Generally pretty good but on a boat add water and by extension corrosion issues on the entire electrical power system. If I put a common rail in I'd want a voltage protection relay and redundant grounds.

I think your biggest issue would be getting anything related to the common rail system serviced. Both diagnosis and repair may entail factory tools or pricey after market ones plus a mechanic that has them and knows when to use them I have a business that uses Yamaha outboards and while we have aftermarket software and a code reader to use a laptop to replicate the factory diagnostic tool none of the local "talent" has any clue of how, when or why to use it.

Common rail does indeed reduce soot build up but it doesn't eliminate it. Depending on how they handled emmisions you may get EGR issues like the intake manifold getting clogged.
VW/AUDI, BMW, Sprinter and Benz all struggled with some issues related to common rail. I'm sure other makes also had some teething issues when going to common rail. But generally a reliable and efficient way to deliver fuel to the engine.