Common Rail Diesels Revisited

[leftbrainstuff]

Originally Posted by buzzstar

Any thoughts bout spares and the ability to use them?

A spare you can't use is equivalent to no spare.

Having both an engineering and mechanical background I always aim to be self sufficient. The holy grail is to be able to make and repair everything.

Reality is something less than everything. Redundancy is also key to being able to keep systems functional even when they are in a degraded state.

I have the knowledge, experience, tools, materiel, parts and test equipment to do everything to our perkins. The only thing not on the boat is a full rebuild kit.

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[buzzstar]

Originally Posted by a64pilot

First thing your going to need is diagnostic software as I assume these won't have OBDII connectors, but they will have something, so will Yanmar sell you the software and connector?

That is new and additional (diagnostic) equipment. Not spares or the ease/ability to use them.

[svthreecheers]

Dockhead I agree with you,that the Commen Rail Injection is the system of the
future diesel engine.The way it works is great and it is easier to fix by replacing
components ,which are very -very exspensive and the injectors for example are
very easy to damage by water in the fuel.
I for one I would never use a turbocharger on my diesel engine in my boat, one more thing to fix,easy to damage and it cuts down the lifespan of the engine
Cheers
Siggi

[truent II]

Got 4JH57 on break-in it just stopped and would not restart. Installer replaced filter and it ran after putting vacuum on return line till no bubbles in fuel. his has happened 3 more times and have bought vacuum gauge to pull clean fuel out when it happens. Thing just stops, running for no apparent reason. Has anyone else had this problem? I?s there a fix

[packeteer]

Originally Posted by svthreecheers

I for one I would never use a turbocharger on my diesel engine in my boat, one more thing to fix,easy to damage and it cuts down the lifespan of the engine

I'm going to have to disagree with you there, at least based on my experience
Using the Toyota Hilux as my example, the engines (1KD) in these will usually do at least 250000km before needing a major service, and there are examples getting around with over 400k on them. There are also blokes running them with aftermarket turbo to 40 psi with no issue.
Now these engines are far from perfect, but turbo shortening the engine lifespan??

[a64pilot]

A turbo usually, almost always does in fact shorten the life of an engine.
Think about it, you get lots more power out of the same displacement. There is no free lunch.
I say usually, cause if you run a turbo engine at normally aspirated power levels, you won't shorten the life, and some will argue maybe extend the life, cause due to valve overlap your blowing cooling air through the engine and the combustion temps can actually end a little lower, but most of the time the additional power of the turbo is used, shortening the life of the motor.
Talk to the power boat guys that run the bigger Diesels and ask them.

[buzzstar]

Originally Posted by packeteer

I'm going to have to disagree with you there, at least based on my experience
Using the Toyota Hilux as my example, the engines (1KD) in these will usually do at least 250000km before needing a major service, and there are examples getting around with over 400k on them. There are also blokes running them with aftermarket turbo to 40 psi with no issue.
Now these engines are far from perfect, but turbo shortening the engine lifespan??

While I am sure it is neither your point nor you intent, how many engines from a Toyota Hilux have you seen being used as auxiliary power on sail boats. The last time I saw a Toyota Hilux engine at sea it was being used as part of a mooring, although I admit I have no recall of a blower. In a more serious vein, I do have difficulty comparing land miles with ocean hours, as well as comparing the ease of and proper timing of routine maintenance, let alone unexpected repairs, while at sea and on land.

[packeteer]

I've seen some on long tail boats, but that's kinda rare

[socaldmax]

Originally Posted by a64pilot

OK common rail is a sort of misnomer, there are a couple of ways to do it.
The most common and the way the Duramax engine does it is with a high pressure pump, essentially nothing more than a high pressure hydraulic pump that pressurizes a "rail" or manifold if you will that all the injectors connect to, the injectors are electronically fired. It requires significant amperage to fire high pressure injectors, but you get all kinds of magic with common rail, like being able to vary injection timing and injector pulse width or even firing an initial shot of fuel to get the fire going just milliseconds before the main injection event and making Diesels spark ignition quiet, a Duramax will shut down cylinders and rotate around which one gets fuel if they overheat, in theory a Duramax will run with no cooling water, each cylinder is separately monitored as if it were a separate engine and injector pulse width and timing is adjusted for each cylinder. My 01 Duramax runs so clean that is passes 01 pollution standards with no EGR, no air injection in the exhaust and no catalyst, just a pure Diesel with no emissions equipment, not true now of course but still impressive, it met standards by strictly controlling fuel, and it is a beast let me tell you, it's not your Grandfathers Diesel. Big old Dually will embarrass most cars on acceleration.
Another way is the way Ford did it with their HEUI injectors that uses oil pressure to highly pressurize fuel in each injector effectively making each individual injector its own high pressure pump.
But an Achilles heel in common rail is fuel cleanliness, many argue 2 micron isn't nearly clean enough, the Duramax injectors suffered from dirty fuel cutting the injector tips, think water jet if you have seen one of those cut through plate steel like butter.
I have never heard of an exploding injector though. The injector tips are extremely fine to get what amounts to a fine mist of fuel spray, at 30,000 PSI plus, you only need and want tiny holes and a tiny bit of abrasive dirt will wreck one.

I have only replaced my Duramax injectors once, but if I remember correctly the injector cost was about $3,000, these are highly complicated precision machines and the price reflects it. Jim Bob at the local tractor dealer is not going to rebuild a common rail injector in the near future, I don't think.

We can argue it to death, but like four stroke outboards, it's coming, won't be long and it will be the only option.


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He is correct on all accounts.

Let me expand a little bit on the downside to common rail diesels. I've got a 2002 Duramax that's currently not running, and I'm not happy about it at all. The engine itself is very stout and capable of amazing power output - it's put out 915 lbs-ft of torque and 450 hp on a chassis dyno, so that was more than 1,000 lb-ft at the crank. But the flaws in the implementation of the injection system far outweigh the benefits.

Clean fuel is paramount at 30,000 psi, any contaminants will destroy the fuel pump and injectors like a64pilot pointed out. I have 3 fuel filters in line; a 30 micron prefilter, 10 micron secondary filter and the factory filter. Even with that filtration, I've suffered a double stuck injector failure that destroyed 2 pistons at 25,000, then replaced injectors again at least 3 times, suffered another engine failure due to a stuck injector, replaced the injection pump once and I'm just barely at 150K mi.

The source of the contamination is actually the hard fuel lines - they rust, just from trace amounts of water in the fuel. They used a nice strong alloy that is highly prone to rust. When you change the injectors, all of the fuel lines need to be replaced. Problem is, for years, the GM tech manuals didn't say that, a friend of mine called someone at GM and they finally added it to their online tech manual system. Same with replacing the injection pump, it never occurred to them to replace the fuel lines and backflush the injectors of all of the debris from the the pump as it ate itself. I'm not saying Yanmar would make the same mistakes, but who would have thought GM or Bosch would have made all of the mistakes they made with these injectors, this design?


I'm not predicting that Yanmar common rail diesels are going to be an unmitigated nightmare. What I am saying is that based on my experience on land, high pressure common rail injection systems are not a good fit for the marine environment, especially if the fuel rail metallic composition isn't carefully selected. The Duramax injection pump isn't cheap, at about $4,000 ea, plus labor, a set of 8 rebuilt injectors is $4,000 plus core charge. Those are dealer prices. You can buy aftermarket, but how many of you do that?

If you thought it was important to have clean fuel before, it will be even more important to have much tighter filtration with common rail.

All of the positive attributes to common rail are nice - quieter, less pollution, more power, theoretical better fuel economy, but the reality is, pilot injection uses fuel to squirt a pre-ignition shot to quiet the diesel down, this decreases fuel economy, they added urea systems and regen mode to burn off particulates for clea nemissions, further decreasing fuel economy. The end result is older Cummins owners brag of fwy fuel economy in the 20-23 mpg range (believable, some claim much higher) while owners of the newest diesel trucks are seeing 13-14, maybe 15 mpg. That's not a fault of common rail, it's an emissions BS issue, but it's coming to an engine near you soon.

Now to the complexity of troubleshooting an engine with a spaghetti factory attached to it. GM has what they call "techs" who plug in their Tech II devices and read codes off of the engine and follow a flow chart in a book because they were never taught proper troubleshooting. They see "low fuel pressure" and the chart tells them to check "commanded pressure vs actual pressure" and they think they're making progress but they don't realize...

the low pressure could be false readings from the pressure sender, a bad pressure regulator, a leak in the fuel rail (under the valve covers, not visible), excessive return flow from one or more injectors, excessive leakage from one or more injectors, clogged fuel filter, bad injection pump - and I'm not even a GM tech. I have not yet met one who could step away from the (basic, defective) flow chart and visualize the entire fuel system and find the simple problem like that one. They throw $8,000 plus in parts at it before eliminating the possibilities.

I wish you all the best of luck, because someone has to get some good luck to balance out all of my bad luck!

[HKTim]

Truent II. Check that no air is getting into the fuel. That was the problem with mine. Turns out that one washer was missing from one of the fuel line connections so need to take each connection apart and check.

[buzzstar]

At sea, I am happy to have dependable and reasonably repairable if needed over the trade offs and benefits that go with some of the more modern technologies. Somehow I suspect my Baja filter, which I still have, does not achieve the needs of more modern set ups. But I like the ability to transfer fuel from a drum if necessary -and be able actually use the transferred fuel.

[01kiwijohn]

If you are still getting air bubbles out of the fuel system, air must be getting in. Check the inlet / supply side of the system for an air leak. Must be there somewhere.

[Dockhead]

Originally Posted by socaldmax

He is correct on all accounts.

Let me expand a little bit on the downside to common rail diesels. I've got a 2002 Duramax that's currently not running, and I'm not happy about it at all. The engine itself is very stout and capable of amazing power output - it's put out 915 lbs-ft of torque and 450 hp on a chassis dyno, so that was more than 1,000 lb-ft at the crank. But the flaws in the implementation of the injection system far outweigh the benefits.

Clean fuel is paramount at 30,000 psi, any contaminants will destroy the fuel pump and injectors like a64pilot pointed out. I have 3 fuel filters in line; a 30 micron prefilter, 10 micron secondary filter and the factory filter. Even with that filtration, I've suffered a double stuck injector failure that destroyed 2 pistons at 25,000, then replaced injectors again at least 3 times, suffered another engine failure due to a stuck injector, replaced the injection pump once and I'm just barely at 150K mi.

The source of the contamination is actually the hard fuel lines - they rust, just from trace amounts of water in the fuel. They used a nice strong alloy that is highly prone to rust. When you change the injectors, all of the fuel lines need to be replaced. Problem is, for years, the GM tech manuals didn't say that, a friend of mine called someone at GM and they finally added it to their online tech manual system. Same with replacing the injection pump, it never occurred to them to replace the fuel lines and backflush the injectors of all of the debris from the the pump as it ate itself. I'm not saying Yanmar would make the same mistakes, but who would have thought GM or Bosch would have made all of the mistakes they made with these injectors, this design?


I'm not predicting that Yanmar common rail diesels are going to be an unmitigated nightmare. What I am saying is that based on my experience on land, high pressure common rail injection systems are not a good fit for the marine environment, especially if the fuel rail metallic composition isn't carefully selected. The Duramax injection pump isn't cheap, at about $4,000 ea, plus labor, a set of 8 rebuilt injectors is $4,000 plus core charge. Those are dealer prices. You can buy aftermarket, but how many of you do that?

If you thought it was important to have clean fuel before, it will be even more important to have much tighter filtration with common rail.

All of the positive attributes to common rail are nice - quieter, less pollution, more power, theoretical better fuel economy, but the reality is, pilot injection uses fuel to squirt a pre-ignition shot to quiet the diesel down, this decreases fuel economy, they added urea systems and regen mode to burn off particulates for clea nemissions, further decreasing fuel economy. The end result is older Cummins owners brag of fwy fuel economy in the 20-23 mpg range (believable, some claim much higher) while owners of the newest diesel trucks are seeing 13-14, maybe 15 mpg. That's not a fault of common rail, it's an emissions BS issue, but it's coming to an engine near you soon.

Now to the complexity of troubleshooting an engine with a spaghetti factory attached to it. GM has what they call "techs" who plug in their Tech II devices and read codes off of the engine and follow a flow chart in a book because they were never taught proper troubleshooting. They see "low fuel pressure" and the chart tells them to check "commanded pressure vs actual pressure" and they think they're making progress but they don't realize...

the low pressure could be false readings from the pressure sender, a bad pressure regulator, a leak in the fuel rail (under the valve covers, not visible), excessive return flow from one or more injectors, excessive leakage from one or more injectors, clogged fuel filter, bad injection pump - and I'm not even a GM tech. I have not yet met one who could step away from the (basic, defective) flow chart and visualize the entire fuel system and find the simple problem like that one. They throw $8,000 plus in parts at it before eliminating the possibilities.

I wish you all the best of luck, because someone has to get some good luck to balance out all of my bad luck!

Very useful information; thanks. Sure makes me think twice about it.

I guess we had better watch people's actual experiences with the new Yanmars.