How long will a diesel engine last?
 

I'm talking about the diesel engines from full-sized trucks (Ford, Chevy, Dodge, etc.), not 18-wheelers. I'm sure that how you use the engine plays a big role in its durability. Let's say it's a truck that's driven daily or almost daily, but doesn't spend a lot of time hauling heavy loads.

And by "how long" I'm referring to miles, not time.

Generally much longer than petrol engines, but there are exceptions. Diesel engines run at much higher compression ratios than sparkers and so need better materials and tougher contstruction to survive. The downside is the materials and construction tend to cost more. There are also differences in daily use. If you make a bunch of short trips they'll tend to lose much of their efficiency. Things are changing now with some of the new designs. This may affect durability as well as efficiency. Hopefully an enthusiast will wander through.

As for the durability exceptions, a number of Diesels (especially those in the early rush to Diesel pickups) were converted sparkers. They just didn't hold up.

Are you looking at anything in particular? Used or new?

A friend of mine has a Mercedes diesel from the late 70s that has like 400k miles on it. Diesel engines have less moving parts. :thumbsup:

I'd say in a truck you can expect anywhere from 150k to 250k miles reasonably so long as you drive it very conservatively. Back in my landscaper days, I drove a Chevy diesel that had something like 220k miles.

there are alot of diesel engines, as I understand it the ones that are converted SI engines are the ones to watch out for.

they have the same number of moving parts as gasoline engines, there are several factors that contribute to their long lifespan. diesel fuel is closer to an oil than gasoline, so it lubricates, where gasoline doesnt. also, diesel engines make their torque at much lower rpm than gasoline engines. this means less valve spring pressure is required to keep things under control....this reduces wear on all valvetrain components...the fact that its turning at a lower rpm also means that for a given number of hours of operation, the diesel will have completed less engine revolutions...again, less wear.

milage guesstimate...200k for a truck...obviously it depends how you're driving it.

Just about the opposite of what you are looking for, but my parents have a 1983 F 150 truck with around 600k km on it. It was my dad's rig truck for a couple years in the 80s, then an all purpose errand/farm truck for a few years. I don't think it has been taken to highway speed in about 10 years, but it still runs reliably.

Should be one third to one half longer than a gas engine. However be sure and factor in the cost of the vehicle. A diesel model will generally cost at least $5000 more than a gas burner.

In my experience diesels will last longer than a gas engine will. This is especially true when the truck is used for heavy towing or pushing snow since it will never have to rev as high.

My estimate would be about twice as long. Mostly due to the slower rpms and where they make there power. The biggest killer of any engine is heat and movement. moving bits cause friction and were stuff out. gas motors spin faster so they wear faster. Also remember to change your oil regularly. clean oil means better lubrication with less contamination and lower operating temperatures. that leads to longer engine life. Also remember most modern diesel engines have turbos. Turbos need oil to live too. more so then the engine. when you first the motor let it idle for 30 seconds or so before you touch the skinny pedal. Its also a good idea to let it idle for at least a minute before you shut it off. this will alow oil to circulate through the turbo and cool it a bit.

Thanks for the info, everyone.

Another question: Would the lifespan of the engine be affected if I was running biodiesel rather than regular diesel?

Now that one I cant answer really. I wouldn't think so as long as the bio is clean. basically they are both just a semi flammable oily liquid....
I'll have a poke around and see what i can find out. I wouldn't mind knowing that too although I prefer petrol motors myself.

That's a good question. I know that emissions are much better with biodiesel, but the claims of longer life are not backed by studies or evidence yet. We'll have to wait and see for that one.

My brother has a 98 GMC cargo van and it is just over 700K miles on it and its only had general maintance done besides a new turbo after like 550K, if you change the oil alone with the oil and gas filter every 4,000 to 5,000 miles you shouldn't have problems, but some can be lemons just watch out for what you are buying.

Assuming the engine is basically good (no defects, etc...) a diesel engine will last for as long as you want it to. It all depends on how good you are to it. As long as you maintain a high standard of fuel and stay up on maintenance/filterchanges (fuel AND oil) you can keep it running until judgement day. I just spent 7 months in the Sudan and saw some, admittedly japanese, diesel engines there that haven't seen clean fuel or original parts in about 30 years. They don't run clean, but they start every time and keep going.

eventually the injectors will have to be replaced, every 200k miles at the outside...

other than that, the vehicle around the engine will disintegrate long before the engine quits.

You tend to here about way more diesel engines going a million miles than you do gas engines.