THP power loss

[Dave Clarke]

At this stage Plan A is to sell it on while it's still in warranty.

Does anyone have any idea what the hard white deposits that clogged up the cylinder head might be?

Have you run on high octane fuel at all (race fuel) as it can cause white deposits in the exhaust, not sure about the cylinder head though, would be possible?
As for hesitation, afaik that is mostly caused by timing issues on the THP, either by a stretched chain (they should check whether it's within tolerances) or a lazy chain tensioner.

[gar074]

Never used high octane fuel - just regular unleaded.

Chain and tensioner have both been changed. The "clogging up" issue is new. When they replaced the chain, tensioner and VVT unit 8k miles ago, the top end was quote "clean as a whistle" unquote.

[pacsab]

White foam/scum/deposit in the engine -in most cases- means water/moisture in it. Reasons might be rare oil change or running short distances with cold engine. Normally should disappear after oil change and leaving time for the engine to heat up and just then floor the throttle :-)

[gar074]

Apparently this was a hard crystalline-like white deposit, not foam or scum.

Citroen seem to know what it is, as their techs instructed the dealer to use an expensive (2 cans @ £50 a pop) cleaner to get rid of it.

[pacsab]

Clear. Understand.

Car still works fine without the problem coming up again?

I am also one of the no-boost-fellows.

[gar074]

So far so good, but I've only done circa 150 miles since the "fix"

[pacsab]

Sorry if already said, as I remember you did not make a pcv deletion. what do you mean exactly by "put a clip on the pipe into the cylinder head to stop the oil seeping out"?

Did you experience oil haze around the sparks at the engine top (as on the attached pics)?



Thanks for your help.

[gar074]

Yes, around the plugs, just as shown in your pics - although I think mine had even more oil!

Re the clip, I got a rather confused (or confusing, at least it was to me) explanation to the effect that the pipe (the one at the top of your pic - on the RH side as you look at the engine - which I assume is the PCV pipe) needed to be fitted with a jubilee clip to ensure that oil didn't seep out of it.

This assumes that the oil around the plugs was in fact coming from that pipe - I've no way of knowing whether that was in fact the case, although I'll be watching it closely from here on in.

[pacsab]

Yepp, thanks gar074!

Yes, actually that is the PCV return hose. So -if I am right- actually they did a PCV deletion without removing the hose (I assume they have to keep the crankcase ventilation because of the emission rules, but wanted to get rid of the quite huge amount of oil which comes with it and -as you said- had even been more on yours than on my pics).

The interesting thing is that on the new THP 200 engines the whole hose is removed and both the intake and return side is capped with a kind of plug. So I wonder how they solve the crankcase ventilation on those engines. Anyone knows?

What is a "jubilee clip" (sorry I am not a native English I understand the words but not the whole phrase)? Would you post a link to a (e-store) picture of it? I am asking because it is not easy to remove the whole pcv hose, especially the intake manifold side as it is quite well hidden in the engine bay, so a kind of "leave-the-hose-there-and-close-it-at-the -return-side-next-to-the-engine-cover" solution would be nice. Maybe others on the forum are also interested.

Thanks in advance!

[mattds3sport]

+1 my delaership knew exactly what this was and said to aerosols of this expensive cleaner will sort it out. ( had a copy of the info rapid with parts / tools needed)

[gar074]

Yes, actually that is the PCV return hose. So -if I am right- actually they did a PCV deletion without removing the hose

No - they left the hose in place, but attached it more securely with one of these hose clips:




As you say, it's tricky to get at, so to fit the clip they had to cut part of the plastic engine cover away.

A really sophisticated solution.

Result- none of that oil is escaping onto the engine cover, so presumably it will all now go into the inlet manifold and f*ck up my engine even more?

[gar074]

+1 my delaership knew exactly what this was and said to aerosols of this expensive cleaner will sort it out. ( had a copy of the info rapid with parts / tools needed)

Any idea what the deposit is that the cleaner is supposed to get rid of? I wish I'd pressed the technician further now, but tbh he didn't seem to have a clue anyway.

[pacsab]

Thanks gar074 I just knew this as "hose clip".

Yeh, really sophisticated. I am afraid that will not help too much, but interested what you will experience.
If it goes into the engine, then might cause problem when it burns.

[DS3RACING96]

a friend has DS4 with 200bhp engine, at its gone into limp home mode, so caps dont help?

[pacsab]

Yes DS3RACING96, you are right, that is the same what I also heard recently.

Sadly it is two separate problems.

Strange that it was not solved even in the new THP 200s.