Possible new owner, question about THP engine

[Indeo]

So there are some stories about this engine. But are there anyone here who has had one with no problems, or atleast not any serious problems?

There's one THP 155 I'm considering, i dont like diesels and there's not many DS3 over 90hp around where I live. I'm Norwegian BTW.

The car in question is a 2012 THP155 ultra prestige with 39 000km.

[Jo67]

I've had my 2013 THP since Jan 2015 and apart from having the temp sensor replaced under warranty, I've had no problems. It's got 19000 miles on the clock, always passes it's MOT without an advisory and likewise never needs anything extra doing at the service. I'm very happy with it.

[BenS]

There are plenty of people here who have had no problems with the engine. And plenty who have, but this is a forum so all the people who have problems tend to come here for help, while fewer people come here to say that their engine runs perfectly fine. The 155 is definitely more reliable than the 150, I think they addressed the timing chain issue in the 155.

I would see if you can find anywhere in Norway that does walnut blasting - look it up on the forum if you haven't already, as this is the best way to look after the engine and prevent potential issues, and at 39000km it will need one soon.

Another thing we see a few of is the HPFP failing, but that can be replaced and resolve the issue.

But on the whole it's a brilliant engine in terms of performance. I'll just wait for some THP owners / ex-owners to leave their better knowledge.

[Indeo]

I would see if you can find anywhere in Norway that does walnut blasting - look it up on the forum if you haven't already, as this is the best way to look after the engine and prevent potential issues, and at 39000km it will need one soon.

im looking at this walnut blasting thing. never in my 32 years of living have i heard of anything like this, im by no means good with a wrench but i do know a little about cars and valve cleaning sounds like something from the 1970s.
im struggling finding a reason for why there is a the need for this. it just sounds like a huge design flaw. what other cars today needs this? cant find anything here in norway/sweden/denmark that does any engine/valve cleaning at all.

but then again my last two cars have been a KIA soul electric and a BMW e39, the bmw engine is bullet proof,
and EVs have like less then 20 moving parts from engine to wheels so theres not much maintenance there. not used to having to do more then an oil change

[BenS]

Most modern gasoline direct injection cars nowadays suffer from carbon buildup on the intake valves, but to varying degrees. Some manufacturers' engines are designed such that the carbon which does form gets burnt off again , or such that the buildup is minimised.

Unfortunately the THP engine in Citroens, Peugeots, and Minis is particularly prone to this carbon buildup, and it can begin to block the valves, or worst case - pieces break off into the engine, damaging the piston and/or the turbo on the way out.

To prevent it building up too much, using the full rev range and doing some long motorway cruises in 5th not 6th will help burn off some of the carbon as it forms, but it will only slow the formation not prevent it.

The only alternative to walnut blasting is pretty much to take the engine head off and manually clean the valves with a toothbrush. Terraclean does nothing in terms of removing the carbon.

BMW have their own walnut shell blasting machines to service the Minis, but the nozzle needs modifying to fit the Citroen engine (which they will not do). Maybe you could try asking Mini dealers/garages if they know of anywhere else that can perform the service?