I spent a bit over three years purely doing diesel engine failure analysis. I had to think about this because we were only called to failures so it was the engines we looked at least. The 8V92 series detroit and the 8RG version of the Cat 3408 (800hp version we called the "Hand grenade") were the most common failures we looked at. Mostly the cause of failure was pushing the engine beyond its service intervals for injector changes and in-frames. The other common cause of failure was defects in the cooling system..often as a result of neglect.
The least looked at engine was the Cat 3406 and the Scania DS11. I saw a lot of operators with the Scania engine that couldn't even remember the last re-build or how many hours they had done...just "a helluva lot" was the usual reply.
There were very few empherical manufacturer's defects. MAN had a bad run with pistons for awhile in the D28XX series. We saw a few Cummins KTA19's but these were big hour engines and there was a lot out there that performed flawlessly for years and years. Some of the most reliable engines I saw were (takes big breath
) Duetz air cooled machines and the Perkins engine mentioned earlier in the thread.
None of them were any good when not maintained properly.
My personal favourite was a Southern Cross 2 cyl hand crank diesel for 20Hp....you just can't beat an engine that fires slower than you can count aloud
I'd say the engine that has the most proven track record for reliability around the world would be either Lister or Gardiner.
On truck engines for miles travelled you'd have to think 60 Series or 3406..probably along with the 16 litre Volvo.
Thats my two bob's worth..
