Fully mechanical diesels

[KarlH]

Does anyone know if mechanically injected marine diesels typically have mechanical injection pumps as well? I've seen some automotive diesels that have mechanical injection and an electric pump, so I thought I'd ask.

[belizesailor]

Yes, still lots of small HP mechanical diesels out there...even the major brands like Volvo and Yanmar.

The very popular Volvo MD series for example is all mechanical. Only electronics are for making starting convenient (glow plug and start relays for example). These electronics are not actually needed to start or run, but allow you to do handy things like hook it all up to a control panel at the helm.

[a64pilot]

No automotive Diesel I know of has an electric high pressure pump?
Maybe you mean a low pressure lift pump?

Only a few types I know of, regular old mechanical injection where say a four cylinder engine has a four cylinder high pressure pump.
Common rail which is similar to a high pressure hydraulic pump that keeps high pressure in a common rail that all injectors are connected to, injectors are electrically fired.
HEUI systems where the injector is actually the high pressure pump too, Ford for example I think used engine oil pressure to run a pump integral to the injector to raise fuel pressure high enough.
However I think HEUI has been buried so to speak as common rail does everything it could, but better.

[model 10]

My old Perkins is now electric. I ditched the old lift pump and now have an electric pump.

[KarlH]

Thanks belizesailor and a64pilot

Originally Posted by a64pilot

No automotive Diesel I know of has an electric high pressure pump

You're right. I was thinking of late-model Detroit Diesel V8s, but the wires are for the electronic control rather than power. (They use a Stanadyne DS4.)

Originally Posted by belizesailor

Yes, still lots of small HP mechanical diesels out there...even the major brands like Volvo and Yanmar.

The very popular Volvo MD series for example is all mechanical.

About three-quarters of the boats I've looked at have a Yanmar or Volvo engine, so that's quite helpful.

One of them has a Perkins-branded MD22 and another has a Yanmar 3JH.

[belizesailor]

Originally Posted by KarlH

Thanks belizesailor and a64pilot



You're right. I was thinking of late-model Detroit Diesel V8s, but the wires are for the electronic control rather than power. (They use a Stanadyne DS4.)



About three-quarters of the boats I've looked at have a Yanmar or Volvo engine, so that's quite helpful.

One of them has a Perkins-branded MD22 and another has a Yanmar 3JH.

As pointed out by others, most small marine diesels have both a mechanical lift pump and a mechanical injector pump. Sometimes, as Guy did, you will see the lift pump replaced with electric, but this is an owner mod.

[newhaul]

Originally Posted by belizesailor

Yes, still lots of small HP mechanical diesels out there...even the major brands like Volvo and Yanmar.

The very popular Volvo MD series for example is all mechanical. Only electronics are for making starting convenient (glow plug and start relays for example). These electronics are not actually needed to start or run, but allow you to do handy things like hook it all up to a control panel at the helm.

Not to split hairs but glow plugs and start relays are electrical not electronic. As is the starter and alternator.


Edit: the alternators do have electronics ( voltage regulator)

[UNCIVILIZED]

Note that some of the newer small Yanmars have electronics controlling their fuel systems. So a lightning strike can cook this component, & leave you engineless. Or the electronics could go bad without Thor's help. Either way, most folks tend to prefer the older, mechanically controlled fuel systems. There are a couple of threads on this within the last year or two, including "Yanmar central" being stingy with new brains for their engines. So that carrying a spare could require knowing the right people, as well as paying a handsome sum for it.

[masonc]

The reason for electronic control engines is emissions. Most of our big generator engines are all common rail and electronic injectors, ECUs, unrepairable stuff. The mechanical engines can't meet emissions targets.

[Captsteve53]

Just posted this on a similar thread re the new Yanmar common rail engines and there issues or not:

Main Advantages:

1) CRDi ensures the fuel injection timing, quantity of fuel and atomisation or fuel spray are controlled electronically using a programmable control module. This allows multiple injections at any pressure at any time (within pre-defined limits), providing a level of flexibility which can be exploited for better power, fuel consumption and emission control.
Noise, vibration and harshness (NVH) are improved with CRDi as a result of the timing flexibility.
2) Your engine sounds quieter and has a better quality of sound. It also runs smoother. You will see fuel consumption benefits as well because greater injection pressure produces a finer spray of fuel (atomisation) that burns more efficiently.

3)Better combustion efficiency is a key part of meeting emission standards. Less fuel is wasted as soot or particulates in the exhaust and deposits in the engine. A cleaner running engine is good for the environment – and for the cost of ownership. Cleaner running improves the long-term durability and reliability of your engine.

4) These days normally very reliable

Disadvantages:

1)Cost Disadvantage

2) A diesel engine with a common rail injection system can cost as much as twice than a diesel engine without a common rail system(But getting cheaper as more commonly used).Price is also driven up by the Electronic control unit, which is a very technologically advanced, key part of the whole Common Rail System

2) If injectors become, even slightly, fouled they can fatally malfunction.
You must hire a certified mechanic to work on a Common Rail Diesel
All the parts of a CRD are very delicate and can break more easily than conventional injectors.

3) Normally requires dedicated shop technician or plug in diagnostic device to trouble shoot,


I have never been called on to diagnose a failed ECU due to lightning strikes(it's possible), radio's , electronics in general (YES) , most ECU's these days are build pretty hardy and designed to accept harsher punishment,

Today on the larger commercial engines (200 Hp up) it's really hard to find a conventional diesel as all the major manufacturers now only use Common rail systems as does nearly all car and truck engines.

For me, personally (and a bit older) I would rather have a conventional diesel for cruising applications (got to love the old GM's/Yanmars/Perkins/Fords and my favorite GARDNER)



Cheers Steve

[KarlH]

Originally Posted by Captsteve53

Today on the larger commercial engines (200 Hp up) it's really hard to find a conventional diesel as all the major manufacturers now only use Common rail systems as does nearly all car and truck engines.

Peninsular diesels still have mechanical pumps, and while I'm no expert on diesel top ends, their injection nozzles look a lot like the older mechanical ones:

6501003 Nozzle, Injector Marine – Turbo Engines – Peninsular Engines

There's no mention of common rail on their site, but they do claim to meet EU and US tier 2 emissions standards.