Thoughts on common rail diesel engines

[Keith-i]

Serious question; How far (and for how long) do you stray from port? (Sorry, that sounds derogatory I know but it is not meant to - I'm trying to find out how people make up their minds on this question).

In my 32' motorboat with CR diesel I have been from Guernsey to Poole which is something like 80nm and also regularly visit the French coastline with trips ranging from 25 miles to over 50 in one leg with port hopping for anything up to week.

In my 6.5m rib with Suzuki EFI outboard I have been as far as Paris via the Seine from Jersey over a 10 day period and some 750nm. Never missed a beat and so far, after 8 years ownership from new, total reliability.

 

[Sandy Bottom]

In my 32' motorboat with CR diesel I have been from Guernsey to Poole which is something like 80nm and also regularly visit the French coastline with trips ranging from 25 miles to over 50 in one leg with port hopping for anything up to week.

In my 6.5m rib with Suzuki EFI outboard I have been as far as Paris via the Seine from Jersey over a 10 day period and some 750nm. Never missed a beat and so far, after 8 years ownership from new, total reliability.

Is that single diesel? Which make?

 

[ianj99]

I had the same issue on a VW Golf TDi 90. Frightening on a motorway or dual carriageway when it happens. I think they diagnosed it as a faulty air mass meter, but we sold it shortly after repair so am still not sure.
It wasn't common rail though, but electronic failure nevertheless.
Seems to me that engines have become so reliable these days; doubt it will be possible to buy normally aspirated and injected engines down the line.

A few years ago a family was killed crossing a dual carriageway in their VW when the ecu decided to shut down the engine just as they were crossing in front of a truck. Apparently the ecu had detected a 'problem' with a injector (Audi/VW's were known for this). I find it incomprehensible that any manufacturer would install an engine management system that puts protecting itself (or the engine) ahead of the occupants safety. Belatedly, VOSA acted quickly to require manufacturers to change this so that the engine is never stopped, but may go into a reduced power mode (limp mode). It was all hushed up and ecus were reprogrammed whenever vehicles went in for a service.

I wonder if this applies to marine CR engines?

 

[Alfie168]

As almost all diesel engines have gone the common rail route there is no avoiding it in the future. The smaller yacht engines will no doubt keep the conventional injection pump and injectors for the moment. When common rail engines started to appear in cars about 15 years ago they got the name of 'common fail', but they have improved over the years. The problem is going to be when your common rail boat engine gets to around 15 to 20 years old. A conventional injector might cost around £50 and injector to overhaul and replace the nozzle(this varies), a common rail injector in an industrial engine about £200. And when you have four injectors to do....... Yes they are far quieter, use less fuel, and have less emissions but the advantages start to disappear when they go wrong. A convention diesel system will soldier on a bit and give warnings of impending problems, a common rail engine will simply stop or not even attempt to start. But this is the future and we will have to live with it, just keep your fuel nice and clean, and the engine compartment completely dry. The fuel quality is vital in a common rail engine, they will not tolerate any kind of bad fuel, dirt or water, if you feed this into the system you will be faced with a huge bill.

Re: dirty fuel.....You appear to have just contradicted Dockhead's friend the diesel expert. There are those on here blaming electrics as being a weakness of common rail.....What? Electrics and electronics are a weakness in themselves regardless. The history of common rail is that Alfa Romeo invented it to enable road going diesel engines to be more flexible in operation in cars by providing more precise fuel metering. This enabled them, along with the turbo charger to have much more usable power bands in smaller engines and have good economy. The wide adoption of the technology shows that it has been a success in cars. Bad connections have more to do with poor implementation of the technology, not the technology itself.

As to boats I think anything electrical and salt water is a bad mix from the word go, and as we know electronics just take this incompatibility to a new level, so maybe common rail is just not the right technology for boats, but given the mountains of other electronics people seem happy to shovel into their watercraft I do wonder sometimes what is going on.

Tim

 

[lw395]

How many threads do we get every month relating to carburated outboards not starting?
EFI has made a huge improvement in motorcycle reliability.
There is only one reason that common rail diesels won't be more reliable than conventional, and that is manufacturers doing things too cheaply.

 

[Sandy Bottom]

How many threads do we get every month relating to carburated outboards not starting?
EFI has made a huge improvement in motorcycle reliability.
There is only one reason that common rail diesels won't be more reliable than conventional, and that is manufacturers doing things too cheaply.

I'm not sure that that is the point being made - to me it is not a question of which is most likely to start / not start - it's a question of what do you do if it doesn't (especially off the beaten track).
(I'm talking about single diesel engine here not outboard btw) :encouragement:

 

[lw395]

I'm not sure that that is the point being made - to me it is not a question of which is most likely to start / not start - it's a question of what do you do if it doesn't (especially off the beaten track).
(I'm talking about single diesel engine here not outboard btw) :encouragement:

I think the point is that no engine is 100% reliable, the aim with common rail or any other 'technology upgrade' should be that failures are insignificant compared to the ever present (but small) risk of un-fixable failures.
So, common rail should be less likely to fail than for the engine to stop working through un-related causes.
There are things that could be usefully done on a marine engine that are not done on cars (possibly for good reason).
e.g. resettable ECU
more useful error codes etc.
Ability to swap out parts.
More intelligent limp modes/fault over-rides.

For instance my little Yamaha trail bike has component level error codes accessible to the rider. Contrast with SWMBO's car, where a red light comes on, telling you to 'have car and wallet towed to authorised dealer'.

Maybe people who want to be able to do first level fix on CR engines might need a spot of training?
And of course high levels of reliability come through a servicing regime.
If you use the same level of neglect as on an old car, then when it goes wrong, you'll be putting the sails up whatever engine technology you have.

If it's safety critical like on a plane, then you might want at least two engines...

 

[Keith-i]

Is that single diesel? Which make?

Single. VW 265 currently badged/marketed as Mercury TDi. Reliability of my engine is lower down my list of concerns than say the risk of getting a rope around the prop or sea conditions hampering my progress/plans.

As to boats I think anything electrical and salt water is a bad mix from the word go,

Tim

Exactly. Hence why electrics and sea water should never mix. If properly designed and maintained they won't! All connections on my current engine are within proprietary o-ring sealed connectors. On the Ford engine it replaced all of the connections were open crimps or similar. Whilst I accept the purpose of all the electrical connections on the old mechanical engine were a lot less mission critical, it was still bad practice and caused problems.

I'm not sure that that is the point being made - to me it is not a question of which is most likely to start / not start - it's a question of what do you do if it doesn't (especially off the beaten track).
(I'm talking about single diesel engine here not outboard btw) :encouragement:

Agreed that repair can be more difficult on a CR and to this end I carry the proper workshop manual and a diagnostic lead which connects to my laptop. So as alluded to by another forumite, some training is beneficial. TBH I always strive to understand my equipment and fix my own problems so maybe I am not the norm . I purposely went down the VW route as any car mechanic in any European port would recognise the engine and the majority of its components. Spares are also better value too.

 

[GrahamM376]

Agreed that repair can be more difficult on a CR and to this end I carry the proper workshop manual and a diagnostic lead which connects to my laptop.

Using those should be real fun, miles from shore, rough seas and blowing a gale

You may well have the knowledge and inclination but most engine DIYers are totally lost on cr engines and whereas many of us used to service our own cars and bikes, the majority now just book them in at the dealers. Virtually everything done to a cr engine needs the cpu resetting, an injector for instance can't just be swapped as it can on old tech motors. Personally, I would avoid a cr engine for offshore use.

 

[Keith-i]

Using those should be real fun, miles from shore, rough seas and blowing a gale

Actually I reckon that is probably easier than trying to methodically check various components bolted on to the engine in the confines of an engine room whilst being thrown around.

Virtually everything done to a cr engine needs the cpu resetting, an injector for instance can't just be swapped as it can on old tech motors. Personally, I would avoid a cr engine for offshore use.

Again, I think that's a slight exaggeration. Whilst the injectors are coded you can readily swap them without inputting their hex code into the ECU, but don't expect top performance until you have. Regardless, I don't carry spare injectors and I doubt many do, so I wouldn't be swapping any mid-passage anyway.

Routine maintenance and simple repairs do not require any 'resetting' of the ECU. In fact, swapping injectors is probably one of the few things that does on my engine.

 

[Dockhead]

Easier to repair IF you have the readout equipment and IF you can fix the indicated fault. Neither are likely to be possible in a small boat miles from anywhere. Conventional diesels are easier to repair under the constraints of a small boat that may be miles from anywhere.

As I said, no expert, and no real opinion, but my chances of repairing a mech injection pump at sea are equal to zero.

I struggle to imagine a problem I could fix on my own diesel (Yanmar 4JH3HTE) which I could not fix on a common rail engine.

You can keep a spare injector or two for either type (and I do have spare injectors, and my meager diesel mechanical skills do go as far as replacing one).

 

[pmagowan]

It is an interesting topic and I am concerned because I have heard this is the way engines are going whether we like it or not. I don't know if it is a good thing. One problem is the idea of an ecu that can only be accessed by specialist equipment. If it is possible to integrate it with technology we already have such as a laptop or onboard MFD then I would be happier. Essentially, if a little electronic gizmo is going to turn off the power to my engine I want it to tell me why. I don't want it to tell me to attend the local service centre. If it will talk to us meer mortals then it might even be an improvement as we get more information about our engines and potential serious faults. I do worry about electronics and salt water but then Garmin seem to manage, as do Raymarine and all the others. It is surely not beyond the power of man to make the gubbins at least water resistant.

 

[AntarcticPilot]

It is an interesting topic and I am concerned because I have heard this is the way engines are going whether we like it or not. I don't know if it is a good thing. One problem is the idea of an ecu that can only be accessed by specialist equipment. If it is possible to integrate it with technology we already have such as a laptop or onboard MFD then I would be happier. Essentially, if a little electronic gizmo is going to turn off the power to my engine I want it to tell me why. I don't want it to tell me to attend the local service centre. If it will talk to us meer mortals then it might even be an improvement as we get more information about our engines and potential serious faults. I do worry about electronics and salt water but then Garmin seem to manage, as do Raymarine and all the others. It is surely not beyond the power of man to make the gubbins at least water resistant.

I think you've hit the nail on the head. For most of us, the concerns about common rail are that it adds an extra element to the trinity of air, fuel and coolant that a conventional diesel requires - for common rail, you need electricity as well, not merely to start the engine, but to keep it running. Of course, we all have electrical systems aboard, but we could always tell ourselves that it was a nice to have, not a must have. Common rail makes it a must have. And the issue of repairability in potentially remote locations without access to workshop facilities is another issue; OK, some common rail engines can be diagnosed and fixed with a lap-top, but certainly not all. The final issue is simply that a marine engine, for safety reasons, must NOT go into some "limp" mode without warning. Bad enough on a motorway - what if you're entering a narrow strait with strong tidal currents? They're not rare - think what might happen if you were in a flat calm making passage through the Sound of Luing and the engine decided not to work at full power while passing the Grey Dogs! The Sound of Luing is scary enough, with strange eddies and swirls, but the idea of being swept into the Grey Dogs doesn't bear thinking about.

 

[maxi77]

I think you've hit the nail on the head. For most of us, the concerns about common rail are that it adds an extra element to the trinity of air, fuel and coolant that a conventional diesel requires - for common rail, you need electricity as well, not merely to start the engine, but to keep it running. Of course, we all have electrical systems aboard, but we could always tell ourselves that it was a nice to have, not a must have. Common rail makes it a must have. And the issue of repairability in potentially remote locations without access to workshop facilities is another issue; OK, some common rail engines can be diagnosed and fixed with a lap-top, but certainly not all. The final issue is simply that a marine engine, for safety reasons, must NOT go into some "limp" mode without warning. Bad enough on a motorway - what if you're entering a narrow strait with strong tidal currents? They're not rare - think what might happen if you were in a flat calm making passage through the Sound of Luing and the engine decided not to work at full power while passing the Grey Dogs! The Sound of Luing is scary enough, with strange eddies and swirls, but the idea of being swept into the Grey Dogs doesn't bear thinking about.

Fair point though perhaps a limping engine is better than a dead one. On nuclear boats we had a thing called the 'battle short switch' which disabled the reactor automatic protection. Perhaps the answer for common rail diesels is for the ecu to give the operating human the options to choose from.

 

[Sandy Bottom]

Fair point though perhaps a limping engine is better than a dead one. On nuclear boats we had a thing called the 'battle short switch' which disabled the reactor automatic protection. Perhaps the answer for common rail diesels is for the ecu to give the operating human the options to choose from.

Exactly. In the mid 1990's we did a lift out and inspection on one of the bigger lifeboats (Arun?) that had aborted a (genuine) rescue due to one engine shut-down. It was one of the early DDEC engines and had gone into limp mode due to overheating. The crew could find nothing wrong at sea, they could see and feel that the cooling was ok. We lifted and inspected it - a failed temperature sensor had caused an aborted rescue with no override for the crew. A battle short would have sorted it as would a three out of four logic circuit.

 

[TheCharteringClasses]

A few years ago a family was killed crossing a dual carriageway in their VW when the ecu decided to shut down the engine just as they were crossing in front of a truck. Apparently the ecu had detected a 'problem' with a injector...

Isn't this possible with old style tech as well though? I had a petrol car that did something similar (in more fortunate circumstances) when the timing belt snapped and it destroyed the valves.

I'm not sure ECU's make this kind of failure more or less likely to be honest.

 

[pmagowan]

Fair point though perhaps a limping engine is better than a dead one. On nuclear boats we had a thing called the 'battle short switch' which disabled the reactor automatic protection. Perhaps the answer for common rail diesels is for the ecu to give the operating human the options to choose from.

That sounds like a really good idea and I am sure it would be possible if we had the access to hack the ecu the way we have with most of the systems on our boats. I worry about proprietary software that is only available to licensed centres at great cost. It should be possible for the ecu to talk to us, tell us what it thinks is wrong and let us over-ride its protection measures. I get constantly annoyed at things, computers mostly (windoze mostly), not letting me do what I want because it thinks I am going to hurt it. I own it! I can kill it if I want. A warning is nice but I should be able to overide it. This could be critical, as others have said in very reasonable and common scenarios.

It may be a case of common rail being potentially better if the manufacturers listen and respond to the needs of what, for them, is probably a small section of their market. I would like a quiet, fuel efficient engine which monitors itself but I am happy to remain tied to a lump that I can get going with a hammer when it counts if needs must.

 

[Jegs]

I believe that Cummins will supply the readout gizmo for at least some of their engines, we all know who would know.

ATB

John G