Today's diesel engines

Are they as robust as they used to be? It wasn’t unusual in days of yore to hear of diesel engines (pickup trucks and cars) making 400K miles without complaining, as long as they got their needed routine servicing on schedule. Today’s diesels have to meet more stringent emissions requirement, and so may run hotter than before. They also probably have more power, and the more complex design that comes with all that. Just wondering if today’s diesel engines are as robust as they used to be? Is 400K miles on the engine without needing any major repairs still feasible?

There are just about no automotive diesels sold these days. I wouldn’t expect light truck diesels to be any more reliable than gas engines , given their complexity. I also think the reliability of older diesels was mostly exaggerated. Some yes, many no.

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No, and it was mostly a myth anyway. Semi truck diesels are designed to go a million miles. Car and light truck diesels are not.

A friend got 240K from his VW and it was done. A friend with a Ford SUV was looking at very expensive repairs at about the same mileage. Both determined this was common from their research.

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I remember an article about a “million mile Mercedes diesel”. Turns out the engine was rebuilt every 250,000 miles, the same I’d expect from a well-maintained gas engine.


1993 Mercedes E-Class Has Original Engine After Nearly One Million Miles (

This was an older one, late ‘60s I think, and in the US.

I think several folks here have gotten over 250k on their gasoline powered vehicles without an engine rebuild.

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We did all the alignments on a company that was a specialist in old MB and other Euros, they brought in a Million Plus Mile Diesel Benz that the customer just spent over $30,000 on getting it back like new…

Now my brothers base Toyota (1998?) stick shift pick up has about 750K on it with only oil/filter changes and tune ups, the valve cover and oil pan have never been off since new… brakes, tires, 1 ball joint, 1 starter and battery’s are all he ever did… The shocks are just there for looks at this point, I think it would bonce less if taken off… lol
Stopped driving it when the cat clogged up…
I want to drop a V8 in it now and make a sleeper out of it… hehe

Wasn’t it the 5.9L Cummins 2 valve that was about bullet prof, replace the head gasket at 500,000 miles and keep on trucking, Dodge 3/4 and up trucks??

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I’ve had 6…and in a few years it’ll be 7.

I’ve heard that, it wouldn’t surprise me, but I don’t have any first-hand knowledge about them.

I went to a new car show several years ago, and there was a diesel Ford pickup with its hood up. The view was like that of some section of the space shuttle with a maintenance cover removed. I couldn’t see any ‘normal’ part of the engine, just hoses, pipes, and heat shields.

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Not surprised you could not see much… a modern direct injection turbo diesel doesn’t look much like the old school engines. They look more like modern gas engines.

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IIRC that’s the truck (an appx 2010 model) that motivated my question. A caller on a call-in radio program said they had 400K miles on that truck, with no problems at all. The only shop work was just the normal recommended maintenance. They were calling b/c the check engine light had recently turned on, and since the truck had never needed an repairs, they didn’t know what to do. The host asked the owner how he used the truck, and he said he used it for hauling stuff, that was his business. He said he drove it 500 -800 freeway miles most every work day. The host said the reason he hadn’t had any problems is b/c that sort of driving is very easy on any vehicle, esp diesels.

I’ll turn that around and say that short hops with a diesel is hard on them. The new smaller diesels in “passenger” trucks are designed with less mass and can get warmed up faster. But it’s hard to get around the fact that diesels make soot when they are cold and that has to be dealt with. In order to run the DPF regen cycle, it needs to get hot for some time so longer trips help facilitate that. People are buying trucks with small turbo diesels in them and treating them like grocery getter cars…

It’s not so much treating them as grocery getters, but purchasing them as grocery getters.