DS3R Engine Issue 2

[DS3RACING96]

well garage isnt sure whats wrong with the engine and they are asking citreon uk what to do !!!! so lets hope they know what to do !!!

[gar074]

Apparently, according to my dealer today, my THP "needs a new cooler pump for the injection unit" (this diagnosis arrived at after lengthy discussions between said dealer and Citroen UK's techie boffins) , and as there's a delay getting the parts from Citroen, I'm stuck with their Fiesta diesel (shiny & new, but incredibly slow) until the 26th!

"Cooler pump for the injection unit". Anyone care to hazard a guess what that might refer to?

[mattds3sport]

welcome to the world of citroen pissin u about lee. prepare to endure weeks if not months of shit and bein car less and power less

[Owd git]

just a thought about your problems guys - I've had several cars in the past that have burned oil (500 miles/pint), indeed I still have one of them that's still going strong so I find it hard to believe that THP engine damage is caused by a bit of oil mist.

I posted this link in another thread - it goes into some detail about the 'Prince' BMW/PSA engine.

Particularly note this point

"At a compression ratio of 10.5:1, the turbocharged engine is compressed to a relatively high level for an internal combustion engine of this type. Precisely this is why the combustion process is monitored also in this case by anti-knock control correcting the ignition angles and charge pressure whenever required."

Now knock does cause damage to pistons, rings etc. and I am wondering if some malfunction in the knock suppression system is what is causing these problems. The valve gear is also fairly complex in having "Hydraulically, infinitely variable phase adjustment of intake camshaft"

Seems to me there is potential in one or both of these to cause problems

Just my £0.02

[DS3RACING96]

well garage phone sum faults codes but will ask more when i see them, car running on 3 cylinders and they did tests and it seems to be leaking one 1cylinder, piston ring was mention. they are striping in down to see if anything else is wrong, but looks like new engine !!!!

[Dangerousfish]

Have they run a compression test yet?

[cyclone]

just a thought about your problems guys - I've had several cars in the past that have burned oil (500 miles/pint), indeed I still have one of them that's still going strong so I find it hard to believe that THP engine damage is caused by a bit of oil mist

The difference is that in our direct injection engine no fuel is going past the valves to clean the oil off of them, so it just builds up and the whole works gets gummed up. it is believed that more than a light mist of oil is working its way down the rear pvc pipe to the intake manifold. When I pulled it off of my car there was actually oil puddled in the pipe and the engine only had 1k miles on it! So now we have a situation where the valves are sticking that leads to the knocking that destroys rings and other things forgive the rhyme and wallah new engine time.

My simplified take on the problem.

[Stef]

So another Racing struck with problems then......................................

I hope they resolve yours quicker than mine, my issue has been ongoing since May hence a brand new replacement car, question is, as soon as I get it should I remove the pipe and put the caps on.....................................

Stef

[Stef]

Lee, how many miles have you done?

Stef

[mattds3sport]

hows tht fair :O i go through all this S**T and am still told tht i need to use premium petrol yet they strip ur engine down and reckon theres a good chance its new engine job. not happy !!!!!!!!!!!!!!

[Owd git]

The difference is that in our direct injection engine no fuel is going past the valves to clean the oil off of them, so it just builds up and the whole works gets gummed up.

I hadn’t thought of it like that, so let’s work this through

998 modified normally aspirated Hillman Imp engine built in 1981, oil usage 500 miles/pint

the inlet manifold is under negative pressure and is carrying a petrol/air mixture. The negative pressure draws oil past the inlet valve guides since there’s no seal due to a high lift cam.

The air/petrol/oil mixture enters the cylinder and is burned – occasionally resulting in a cloud of blue smoke when accelerating away after descending a long hill (increased vacuum in the manifold due to a closed throttle and engine braking).

The engine does not knock due to the fact that the ignition timing is mechanically retarded sufficiently to prevent that happening.
The engine was built in 1981, has done 45,000 miles, revs to 8000 rpm and develops about 75bhp (don’t laugh – that was pretty good in those days!), and has not developed any problems.

THP engine

The inlet manifold is under up to 0.8 bar positive pressure and carries lightly oiled air (I assume that it gets in there from the PCP system?). The air/oil mixture enters the cylinder where it is joined by petrol vapour and burned.

I don’t really see much difference between the two engines at this point – the inlet valves run fairly cool since they are cooled by the incoming air, and the stems do not get hot enough to carbonise the oil coating them, so they are unlikely to gum up.

I can however see a significant difference with the exhaust valves. The THP valves run much hotter than the Imp

Extract from the ‘Prince’ engine item in the link above....

“Precisely this is why the valve shafts measure only 5 mm or 0.20´´ in diameter, with the hollow
shaft outlet valves being filled with sodium.”

Nicked from an aircraft website........

“The reason sodium filled exhaust valves are used is to allow better transmission of heat from the valve face up the stem - the very heat that carbonizes the oil, causes excessive stem wear and sticky valves. This heat transfer is necessary in order to prevent the outright failure of the valve at the point where the stem joins to the valve end and it is the very area that is fully exposed to the blast furnace temperatures of the exhaust gases.”

Now the Imp engine has larger diameter stems and doesn’t use sodium filling because the heat generated is nowhere as great as the THP which according to the document is up to 950 degrees C

Throw in the fact that for efficiency the THP is presumably kept operating as close to a ‘knocking’ condition as possible by the ECUs, and there may at least two factors at work here.

Why are only some engines affected? Dunno. Anyone care to chime in here?

Once again just my £0.02

[DS3RACING96]

Have they run a compression test yet?
yes they have
only done just over 4000miles
treated this car so special as got it just be for my mum past away, only ever put my foot down till engine had warm up for 30min atlest, just if they put a new engine in, does it come with a 3year warrenty??? at will it just happen again???

[mattds3sport]

i still dont get compression test even tho mine has exact same symtoms wot is my dealer THICK? amount of times ive told him of all these engines goin and all he can say is ive gotta follow citroen uk procedures :| i will get done for assualt if he sez tht 1 more time just sort the bloody car out :@

[Stef]

Have they run a compression test yet?
yes they have
only done just over 4000miles
treated this car so special as got it just be for my mum past away, only ever put my foot down till engine had warm up for 30min atlest, just if they put a new engine in, does it come with a 3year warrenty??? at will it just happen again???

You have my sympathies mate. I've been unwell for over a year now and currently on morphine 24/7, when I got my car in May it picked me up for a bit but with all this messing around it just zaps you completely, so I know what you mean about it being special. I sincerely hope they sort you out really quick, and you too Matt.

The DS3 is such a brilliant car, it's such a shame we're having these engine problems to deal with.

Stef

[cyclone]

The inlet manifold is under up to 0.8 bar positive pressure and carries lightly oiled air (I assume that it gets in there from the PCP system?). The air/oil mixture enters the cylinder where it is joined by petrol vapour and burned.

I don’t really see much difference between the two engines at this point – the inlet valves run fairly cool since they are cooled by the incoming air, and the stems do not get hot enough to carbonise the oil coating them, so they are unlikely to gum up.

I believe you are underestimating the amount of oil actually making its way thru the pvc system (Possibly why this pipe was removed on the thp200 in the RCZ & DS4) and the cleaning power of the fuel air mixture on the intake valve that is not present in the thp, Hence the info rapid where cleaning solution is induced into the induction system prior to the intake manifold.

I know we all have our own views on what is causing the problems, just wish PSA would get off the pot figure it out and fix it. It may make economic sense in some strange way to ignore it and replace a few engines and cars but it sure inconveniences and stresses out us poor owners.