Common rail vs mechanical injection

[Cow pi]

I'm looking to buy an older Case Maxxum 125 for an all around ranch tractor. What are the pros and cons of common rail injection vs mechanical?
Is there any difference in fuel economy? Long term maintenance?

I'd appreciate any input.

 

[CausticUrbanCoast]

Why that tractor? (There are two versions a tier 3 and a turbo tier 4)

I imagine it is in the lower price range based on its testing performance by the dept of ag?

 

[Hall00]

A common rail is usually self-priming at the injectors.

A mechanical injector is a lot cheaper than a common rail injector.

A common rail will usually be more fuel efficient since the computer controls the pulse width and will adjust for load.

Clean fuel is the most important thing. Filters are cheap compared to injectors or injection pumps.

 

[denchen]

Common rail needs a computer. Computers run on electric. Electric and water do not mix and if the water gets in the computer, the engine usually stops, and the man who has to fix it usually gives a sharp intake of breath and smiles. Mechanical pumps, provided they get a steady flow of clean diesel, keep going. They usually use a bit more fuel, don't produce as much power, but they keep going. And they keep going. Mechanicals don't have EGR or DPF to worry about and give off more CO2 etc. so the owners are not so popular with tree hugging environmentalists that think we should all be using horses.

 

[Tx Jim]

Ditto on common-rail requires cleaner fuel than older style IP. My neighbors Kubota M8560 got water in fuel allowing fungi growth in fuel system. Fuel pump & injectors had to be replaced to the tune of $7500 at local dealer.

I've had water get in fuel systems on my Kubota M7040 & Ford 6700 due to my storage tank water contamination. I just drained water from tractor tanks, installed new fuel filters & added fuel conditioner that contained Biocide. That was several yrs ago & tractors will operate today

 

[Hay Dude]

I'm looking to buy an older Case Maxxum 125 for an all around ranch tractor. What are the pros and cons of common rail injection vs mechanical?
Is there any difference in fuel economy? Long term maintenance?

I'd appreciate any input.

You will love that tractor. Parts are really common and maintenance is very easy.
Long term, mechanical injection is simpler and easier to maintain. Common rail a bit more efficient since it’s computer controlled and can be more powerful with the time ing of the fuel injection events.

 

[LouNY]

To me the really big plus for the common rail is cold weather starting, it is fantastic when it works right.
I don't like the necessary electronics and the worry that they may fail at any time.
The common rail will produce a bit more power a bit cleaner.

 

[ROUSTABOUT]

Common rail needs a computer. Computers run on electric. Electric and water do not mix and if the water gets in the computer, the engine usually stops, and the man who has to fix it usually gives a sharp intake of breath and smiles. Mechanical pumps, provided they get a steady flow of clean diesel, keep going. They usually use a bit more fuel, don't produce as much power, but they keep going. And they keep going. Mechanicals don't have EGR or DPF to worry about and give off more CO2 etc. so the owners are not so popular with tree hugging environmentalists that think we should all be using horses.

But then, soon as we go back to horses and drag all the plows out of the thickets and brush....they will start belly aching about all the methane from the manure....

 

[CausticUrbanCoast]

Interesting that the "efficiency" myth continues after the whole dieselgate thing.

High pressure common rail is not any more efficient than mechanical. The injector nozzles determine the maximum flow and pattern.

However, the Teir 4 version if that tractor will seem more efficient as it utilizes a turbo. By under tuning and requiring the turbo to activate for full power there is a perception of fuel economy.... at a significant parts and maintenance costs when something fails.

So if you want to pay a few dollars less to refill the tank and a few hundreds more maintaining, that would be the version.

There has been very little advancement in diesel efficiency in the last 50 years other than a rotary diesel engine that was released a year or two ago (half size, same power density).

 

[LouNY]

^^^^
Sorry you are mistaken

 

[CausticUrbanCoast]

^^^^
Sorry you are mistaken

Turbo rebuild is 500+ plus all of the piping, so around 1k.

Turbos are killed faster when shutdown hot. Idle for half an hour so they cool down kills any savings.

Average turbo life is measured in 100s of hours before the bearings wear out.

Will never buy a turbo diesel again.

 

[LouNY]

Dang!!!
Must be all the turbos on the farm are shot to heck, most of those turbo'ed diesels
have well over 6000 hours on them a few over 10,000 hours, they are getting a bit tired.
We idle down for the last few minutes and don't work them hard before shutting down,
but they sure as heck don't idle for half an hour.
My little V6 diesel RAM had 98,000 miles and several thousand hours on it when I traded her in
and it had no issues to speak of.

 

[CausticUrbanCoast]

Dang!!!
Must be all the turbos on the farm are shot to heck, most of those turbo'ed diesels
have well over 6000 hours on them a few over 10,000 hours, they are getting a bit tired.
We idle down for the last few minutes and don't work them hard before shutting down,
but they sure as heck don't idle for half an hour.
My little V6 diesel RAM had 98,000 miles and several thousand hours on it when I traded her in
and it had no issues to speak of.

Then you are lucky, after the third one I sent it to the scrap yard.

 

[ruffdog]

^^^^
Sorry you are mistaken

^^agree. It took diesel a bit longer to get "high-tech" but especially with pick-ups, they are much more efficient than a dozen years ago. Higher compression, higher boost, higher pump pressures, precision injectors, computer controlled, variable cam timing......the list goes on.

 

[RickB]

Turbo rebuild is 500+ plus all of the piping, so around 1k.

Turbos are killed faster when shutdown hot. Idle for half an hour so they cool down kills any savings.

Average turbo life is measured in 100s of hours before the bearings wear out.

That's absurd. Top to bottom. Idle for a half hour? 27 minutes wasted.

 

[CausticUrbanCoast]

That's absurd. Top to bottom. Idle for a half hour? 27 minutes wasted.

That's what was recommended after the first one went. Couldn't give it away after the second one went, dealers wanted too much to repair it.

 

[Tx Jim]

Turbo rebuild is 500+ plus all of the piping, so around 1k.

Turbos are killed faster when shutdown hot. Idle for half an hour so they cool down kills any savings.

Average turbo life is measured in 100s of hours before the bearings wear out.

Will never buy a turbo diesel again.

My '91 JD 4255 with 11,500+ hrs on speed/hour meter has original turbocharger that was on it when it rolled off assembly line at Waterloo,Ia. My '11 Kubota M7040 with 1800+ hrs on speed/hour meter has original turbocharger also.

 

[RickB]

That's what was recommended after the first one went. Couldn't give it away after the second one went, dealers wanted too much to repair it.

So you claim.

 

[bnold]

2011 Dodge Ram 3500
225,000mi
5,250hrs

Stock VGT turbo, happy as can be.

 

[Hall00]

TuRbO dIeSeLs BaD...that's a new one.

Turbos make diesels much more efficient. Let them cool for a minute or 2 after WOT and then shut it down. Or don't. The oil coking in the bearings is a myth founded in a one-off extreme case...99% of people couldn't replicate that scenario if they tried.