Why do diesels last longer?

[snelson]

I was explaining to a friend of mine at work about my new pride-n-joy Delica, and said "yup, only 95K kms on her - and you know diesel's.....they'll go forever!" "Why's that?" my friend asked? "Uuuuh I don't really know - that's just what they say" I said sheepishly.

Why do they go forever? Seems to me there's just as much heat given off and moving parts as a gasoline engine, but why do deisel's typically last longer? With the higher compression I would've thought the opposite.

Can anyone please enlighten me as to why diesels usually last longer than a gasoline engine?
Steve

[jessef]

Pretty simple.

Diesels burn oil while gasoline engines burn solvent .

Lower RPM's

Diesels are built a lot stronger (internal castings) because they have to withstand the combustion and heat stresses.

Twice/x3 the oil.

Diesel's are injected in a fine mist where it combusts and does a slow burn, pushing the piston down rather than hammering the top of it like gas engines.

Off the top of my head that's pretty much most of what I know.

Also in general they tend to breakin over 100,000 miles. MPG gets better as the miles click on opposed to gas engines.

Anyone have something to add ?

Jesse

[jrman]

I was told by a diesel mechanic that the main reason for longevity is because the internal moving parts are generally manufactured to higher standards compared to gas engines - this is in order to withstand the higher compression and stresses of the diesel combustion process. He said gas engine would have to be "balanced / blue printed" and have very high quality internal components installed to be comparable in overall quality. Such comments are clearly a generalization aboud Diesel engines. For example, does anyone remember the 6.2L GM gas engines converted to diesel??? They were famous be being garbage. I had a bad experience with a Ford 6.7L 1985 F250, but it was fuel injection related ($4500 repair and at least partly due to a incompetent mechanic) - so really not a fair assessment. Regardless, Mitsubishi is quite famous worldwide for building some of the best diesel engines.

[JMK]

Someone from the Tractor community asked the same question back in 2002, and it became quite a long thread. In fact the question has been asked so many times in various forums Google has quite a number of pages on the subject.

[loki]

I think it has a lot to do with the way gas and diesel burn. Diesel burns and the expantion that results is slower and more gentle where as Gas (fumes) explode more than burn and the expansion is much more... well explosive.

[Jester]

Someone from the Tractor community asked the same question back in 2002, and it became quite a long thread. In fact the question has been asked so many times in various forums Google has quite a number of pages on the subject.

there is a TRACTOR forum???
What is this world coming to?

[konadog]

I had a bad experience with a Ford...

LOL! been there, and have heard the same lament from many, many others. Some real horror stories of terrible incompetence and abysmal quality control, right from the design to the factory floor. I would never own another - Very resentful. Thank God for the Japanese auto makers who actually seem to care about quality. And if you want a fair assessment on the issue check out the Consumer Report or Lemon-aid.

[psilosin]

Another reason they likely tend to last longer is that most diesel owners are pretty meticulous with their maintanence schedules because they know diesels are way more expensive to repair and are also more susceptible to damage from sloppy maintanance than their gasser kin. Kind of a self fullfilling prophecy.

I'm sure this doesn't hold for all examples from the various diesel forums I hang at people are way more anal about maintanace, usually revolving around the horror of soot buildup and oil pH.