I am not sure a diesel needs more and more expensive scheduled maintenance than a Lyco/Conti. In my experience there is a lot of unplanned and costly stuff to be done on those engines.
I can easily fry my Lyco by incorrect operation which is not possible with the diesel engines. I would never give my aircraft to another pilot because of that. Less of an issue with a diesel.
It is different on this side of the pond.
Let’s compare the C172 with the centurion 2.0 (155hp) 24lph at 115kts with the Lyco 320 (160hp) with about 38lph at 105kts.
Avgas around 2,50 Euro and A1 around 2 Euro:
95 Euro vs 48 Euro. So you save 47 Euro (or $50) per hr and half your fuel cost.
Let’s compare the C172 with the centurion 2.0 (155hp) 24lph at 115kts with the Lyco 320 (160hp) with about 38lph at 105kts.
I’ve flown behind a O-320 for some years and my average was 28l/h Mogas which is cheaper than Jet A1 in Germany.
I would never give my aircraft to another pilot because of that. Less of an issue with a diesel.
Well, the engine may be harder to mismanage so they just shag the rest of the plane instead 
A DA42 not a million miles from here was removed from self fly hire rental because the pilots kept breaking bits on it.
Here (local copy) is a BEA report on Thielert engine reliability. Section 2.2.2 is interesting…
(just realised this is a rewritten English version of the French language one posted before)
(just realised this is a rewritten English version of the French language one posted before)
I did not realise there was an English version. Sorry for posting the French one.
I happen to have quite some experience with these Bosch developed three radial piston pumps. They are very delicate, fuel lubricated and should you get air in the fuel system, they do not auto-prime and they can even get destroyed due to lack of lubrication. Normally you have a classical low pressure pump in front of them but even they are not enough to prime these pumps should they have air. I would clearly classify the high pressure fuel pumps as the #1 troublemaker in common rail diesels. I always keep at least one in stock and the only failure mode they have is a very simple one: the engine dies.
Bosch had had numerous issues with them since the widespread introduction of common rail and changed the design several times to overcome the reliability issues. I do not know which generation is used by the Thielerts but considering when the engines were developed, it surely is an early generation.
Achimha
The pumps are very different from the Bosch car pumps because they have to be modified to run on Jet A1 that is not as good as Diesel fuel when it comes to lubricatinf the pump internal components.
The fact that the factory put a hard life on the pump seems to reflect the fact that they seem to share your views on pump life, however because on the differences between the car and aircraft pumps both in componants and fuel used I think that direct comparison is invalid.
The only failure that I have seen that has resulted in an airborne shutdown was with a 1.7 with a gear box almost at the end of its life, fortunaly the engine was fitted to a DA42 and the aircraft made an uneventful landing.
These engines have a bad reputation for reliability only because the industry has failed to understand them and hangs onto the story’s of the early problems while almost wilfully failing to see the improvements in reliability made over the past few years, if you want to see an example of lack of reliability you need to look no further than Lycoming O-235 cylinders installed in C152’s.
I understand this was indeed a total engine failure…
As the discusstion between Lyco/Contis and Diesel is ongoing…. what are the hard facts in cost when replacing/overhaule (Lyco only) the Engine Avgas versus Diesel ?
Would wonder who much lets say a O360 versus a CD155 cost.
So, I could think to buy a Lyco C172 or C182 or a Robin and when engine is due change to Diesel ? what would be the difference in Price?
