My personal experience with medium speed common rail engines started back in the early eighties and I have to say that in a way it was like starting out all over again in many ways.
We thought fuel delivery pressures were high in the old days but common rail pressures of sometimes in excess of 20,000 psi showed otherwise.
So different all round.
As well as fuel economy emissions seemed to play a very large part of it all.
No manual injection timing, the death of spill timing, no injectors upside down on pipes to see spray patterns, dangers of any leaks increased dramatically compared to the now termed " old days "
Told on courses that ideally no fuelpipes to be re used, all renewed ( which of course we never do ) and being told of any LFO contamination by substances containing no lube properties and everything from the fuel tank up to the last port of call (the injectors ) should be changed.
Seeing CR injectors with solenoid and then ceramic stacks operating them thousands of times a minute and naturally stripping same to see what makes them "tick" ( I couldn't do anything with them unlike the old days when being taught how many to overhaul them, resetting pressures, regrinding pintles with Merlin grinders etc etc. )
Some engines require replacement injectors to be programmed to the ECU when fitted.
Wish I had a pound for every injector I have overhauled sinc 1960 .
Learning about ECU /ECM electronics, searching for dry joints on boards and letting in new IC's etc into the boards using our new purpose built special soldering station built especially for the job.
Learning common faults with Bosch for example, the first time despite having all the million pound electronic kits taking a couple of days to isolate the fault.
A miniature green O ring in the fuel regulator valve having a small nick in the ring, hard to see with the naked eye but causing a intermittent collapse of pressure in the fuel rail thus cutting out the engine which in this case requires 300 bar for the ECU to lift the pintles to enable a start up.
Engine may well restart and run for several days, here we are thinking ECU/ HP pump problems etc etc when all the time it's a fourpenny hapeny O ring, but it's a special thickness one and not in your big boxes of O ring kits you carry.
Next time you have a similar problem you check/replace the O ring first before delving further into the problem.
Other one to be learnt back in the eighties was yet again a collapse of pressure in the fuel rail causing an intermittent shut down.
Once again testing (among other items) injectors.
Scoping the injectors with a four channel scope kit.
Or removing and Function testing on the bench with special kit.
Or the cheap way out ( which often shows up straight away ) the Hampster bottle kit.
Calibrated plastic bottles attached to the spill returns and looking for an excess of 10% fuel return flow rate.
Once learnt you carry spares but the initial learning curve here causes a lot of the old hands to throw up their hands in the air saying bring back the old days, we all knew what we were doing then, all theses electronics, it's ridiculous.
Where I am some of the old hands can't ( or won't ) take it all onboard and yet on the old " mechanical installations " they were top of their game but find the new electronic world difficult to understand.
Now we have LNG engines Common Rail.
So basically the common rail engine has a series of sensors all over the engine reporting to a programmed ECU who instructs sets of actuators again all over the engine to run at the most efficient way it can, throught rev ranges, temp. ranges and of course load ranges.
I am still totally amazed at some of the changes brought about by Common Rail Management systems.
We do a lot of DPF ( diesel particulate filters ) regenerations whereby you program the ECU and it retards the injection timing which of course causes the engine to run a controlled overheat temperature and lifts and holds the RPM for maybe 20 minutes and burns off all the excess carbon in the exhaust uptakes and into atmosphere .
God help an engine with a lazy stat. or early headgasket failure problem although of course all the temp. Sensors will monitor this and hopefully not allow an overheat situation to cause any damage.
Some diagnostics can be a pain in more ways than one.
Diagnostic equipment is expensive and every year you have to have it updated to keep up with the latest technology .
Parts such as injectors/HP pumps ECUs etc can approach the value of an older/higher houred engine and when you have tested parts approaching the makers top limits you have to decide whether to renew/replace them although they are ok for further use.
That all said there can be (like the Anzipods ) no doubts that they are here to stay as they are much more efficient, squirt much much less into atmosphere and require less running costs all round.
There is so much further to this subject that one can fill several pages talking about it and when you crack a problem on an engine that has been elsewhere for an attempted unsuccessful repair by renewing expensive parts unecesssarily it does bring back the old "Buzz " which I guess drives us all onwards.
In passing have a look at Caterpillars HEUI interpretation of CR, done a few of them, very clever whoever designed it.
No injector pipes here!
However if you wish to remain in the trade you have little option other than to try and take CR onboard to avoid being " left behind " in the ever changing world of CR.
Onwards and Upwards with CR!
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.