C5 2.0HDI Oil and combustion gasses smell in cabin

[ccaesar80]

Hello,

There are now a few months since I bought a neglected C5X7 (DW10CTED4 engine).

I noticed there is a smell of oil in the cockpit after the engine warms up (about 15 min). I knew there is an oil leak around the upper oil pan seal.

With the cabin air recirculation on, the oil smell goes away but there is still a smell of what I think are combustion gases (but I am not sure).

In the meantime I discovered another oil leak higher up in the area of the injection and the vacuum pump. The visibility is now good there but it seems to be more around the injection pump joint on the cylinder head.

I also opened the injectors cover and found varnish like deposits there.

What could this deposits be? It looks oily but since it look rather clean I am more inclined to think it is diesel (although it doesn't smell like diesel).
I read here in another post that it might be blow by from a loose injector, which would also explain the combustion gasses smell. However, the engine starts instantly every time, no matter the temperature or how long it's been sitting so wouldn't suspect any loose injector. Woldn't that be noticeable in the running of the engine?

Is there possible that the gasses smell to come from the leak around the injection pump?

I'm going to start dismantling things aroud the injection pump to get a better view.
I also wanna check if the injectors are tight. However, I am not sure how to do that since the bolt tighten specification is by torque and angle. If it was only torque I would have just retighten with the torque wrench. I could loosen the bold and redo the torque and angle, but I'm a bit reluctant to do that since that would imply to replace the bolts if if want to really do it right. (since a loose injector is not my first guess, I would leave that more at the end)

So if you have any thought and suggestions about any of these problems, I would like to hear your idea.

Thanks!

[mickthemaverick]

I had very similar odour issues with my last C5 2.2HDi when I first bought it. It looked as though injector 3 was moist around its seat so I gave its bolt a tweak and never had the problem again!!

[ccaesar80]

Hi Mick,

You are definetely right. It's a injector seal leak.

I looked more carefully and saw some crud around injector no 3. I can even see that the plastic cover is more shiny above that injector.

So I set my torque wrench to 28Nm (this is the torque setting on the injector bolt of my Megane 1.5dci They seem to be about the same thread size).
I tried to tighten it and it moved easily. I stopped immediatelly and checked all the others just to get a feel of how tight they are. They all moved the same.
Then I put my torque wrench to 12Nm and tried again increasing the torque by about 2Nm every time. They were all torqued under 20Nm. I would say around 16Nm. That for me seems incredibly loose.

Anyway, I set the torque to 24Nm and tighten no 3 which clicked after about 20deg of rotation.

After that I started the engine and surprise. I saw fumes coming out of injector No2. Not actually from the injector itself but more towards the back.

I tightened it to 20Nm, restarted the engine, still fumes. I set again to 24Nm and tightened it again but it moved a lot so I was afraid to push more. I think I tightened it about 30deg and it is somewhere around 22Nm. After another restart I couldn't see any more smoke. I did a 20min test ride and I would say the smell is gone, but I will do another check tomorrow.

Anyway now even if the problem seems to be fixed I think I will change all the seals anyway. The car has 250k.

I am very surprised however that all the fumes got so easy into the cabin. Is there any way to protect the air intake from cases like this? Maybe root a duct from the intake to the side so there is less change that air from under the bonnet come inside?

Another thing I wanted to adress is the air quality sensor. I tried to see if the recirculation activates automatically because it should have sensed the poluted air coming from the leak. However, Lexia reports the sensor as not installed. Isn't this sensor standard on all C5s?

[PaulC5]

In the Haynes manual for the 2001 to 2008 C5 it gives the injector clamps as 4 Nm plus 65°. This may not be correct for your car though.

[ccaesar80]

I know the spec for my car, DW10CTED4 (RHH) engine. It is 7Nm+55deg. That is usefull for a new bolt. For the old ones, since they are stretch bolts, they should not be retightened, so that's why I kind of played it by ear, being carefull not to overdo it.