Intercooler hoses - where does the oil come from?

[Jim Haseltine]

Two weeks ago yesterday I did an oil change including draining and cleaning out the intercooler hoses. Today I removed a bit over half a litre of oil from the intercooler hoses - slightly more from the rh than lh.
So, how's it getting there?
Anybody ever had problems with the PCV oil separator?

[Jim Haseltine]

Start up smoke is becoming frustrating. Thursday morning - no smoke. 8 hours later - loads of smoke, kept smoking at every set of traffic lights for 10 minutes. Friday morning - a little smoke, kept on for around a mile. Friday evening - no smoke. Saturday evening after being parked up for nearly 24 hours - no smoke. After cleaning the hoses today - no smoke. 4 hours later - smoked like it did on Friday morning.

[Doug_RS6]

Perhaps I'm being thick here and I'll admit I know little about the PCV system on this car. But that sounds a bit like an issue with burning oil vapours at the wrong times and perhaps rate.

[Doug_RS6]

Although if you are getting large quantities of oil anywhere then it sounds like an issue. Normally I suggest running a catch can set up to rule out PCV issues but not so easy on these.

[Jim Haseltine]

At the moment I think there's 3 possible sources for the oil.
1. Turbo front seals - there's no smoke when the engine has been running for a short while (usually, that is, Thursday evening was different) so I now don't think this is the problem but I could be wrong.
2. The PCV valve/oil separator set up
3. oil draining down through the intercoolers from the throttle area - unlikely I think and then there's be the problem of how it's getting there in the first place.
My current favourite is the PCV.
Looking at the study guide that Ian helpfully posted, crank gases from the left head go to the PCV valve then into the oil tank separator then back to the separator in the PCV valve, gas from the right head go directly to the separator in the PCV. De-oiled gas should then go to the intake in front of both turbos or into the inlet manifold depending on manifold pressure and a number of non-return valves. Where the oil goes from the PCV separator I'm not clear on, but I think it drops into the RH rocker cover.
Back in December I had the intercoolers off for a week or so and during that time there was a slow weep of oil from the turbo outlets, I'd blocked them with paper towels which were saturated by the time I got around to reassembling things again. I'm off work later this week so I'm going to get stuck into it then.

[Nobby]

There's a few other potential issues:

- If you had a broken PCV system i.e. completely blocked then you'd get lots of chuffing if you removed the oil filler cap when the engine was running. PCV should drain oil back into the sump and send vapours into the inlet. As Doug says you can normally fit a catch can to see how much comes out. The system normally has a one way valve, an oil seperator and lots of pipework.
- If you had a large amount of blow/warn piston rings you also get an excess of PCV pressure, which would force oil vapour in through the breather system. Compression test would show this up.
- You could also have a problem with valve stem seals (leaking into the cylinder during driving and pooling when the engine is off). Would need a borescope/camera through the spark plug hole to look for oil. The oil in the intercooler hoses could be a coincidence but unlikely. The volume of oil you are mentioning is more than I've ever seen.

How easy is it to remove the outlet pipes from the turbo(s)?

The oil seperator is on the O/S part of the engine, and includes the dipstick section. If you look for the C6 RS6 Study Guide (IanH hosted a version a while back) and there's also a pretty good video on YouTube called 'RS6 5.0 liter V10 TFSI engine service training manual' which covers lots of things.

Chris

[Jim Haseltine]

At idle tonight after getting home I pulled the dipstick. No massive pressure - a lot of fumes but not enough pressure behind them to lift the dipstick or blow past it when I placed it back to cover the filler. The intermittant smoke on start up is what I find frustrating, all I got today when I left work was not what I'd consider unusual for any car that had been parked up for 9 hours and cleared once the fast idle stopped. There are two oil separators, a main one in the oil tank and a secondary in the PCV valve assembly.
Anyway, I'm going to pull the pipes on Wednesday evening or Thursday morning and see if I can find where the source of the oil over the following days.

[Stiggles]

At idle tonight after getting home I pulled the dipstick. No massive pressure - a lot of fumes but not enough pressure behind them to lift the dipstick or blow past it when I placed it back to cover the filler. The intermittant smoke on start up is what I find frustrating, all I got today when I left work was not what I'd consider unusual for any car that had been parked up for 9 hours and cleared once the fast idle stopped. There are two oil separators, a main one in the oil tank and a secondary in the PCV valve assembly.
Anyway, I'm going to pull the pipes on Wednesday evening or Thursday morning and see if I can find where the source of the oil over the following days.

What colour is the smoke Jim? I'd white smoke in my mb quattro on startup that disappeared after it was warmer which was due to worn piston rings, I imagine a scope would reveal any scoring on the bores.

[Jim Haseltine]

The smoke that concerns me is blue/white and hangs around in a cloud, unlike normal start up smoke which disappears quickly. Like I've said, it's not all the time - leaving work yesterday there was nothing unusual, leaving home this morning there was a small cloud of blue stuff in my drive way. I'm going to put a scope into both the inlet and outlet of one of the turbos this week so I may as well look in the cylinders too at the same time. I'll run a VCDS scan before I do anything.

[Jim Haseltine]

Considerable amount of smelly smoke tonight which died down to the occasional puff after a minute or so although the idle stuttered a coouple of times which is something I've not noticed before. It was still smoking in traffic for the first mile or so but no more than a couple of other cars around me.
Ran a VCDS scan when I got home which listed just the faulty tyre sensor I was expecting.

[Stiggles]

Hopefully it's nothing too major, but that does sound quite similar to what I had, although mine was diagnosed by oil covered plugs so I imagine if the plugs are dry you should be safe on that side of things.

Turbo diesels usually fill their pipes with oil once the turbo is on its way so may be as you suspect regarding turbos

[Jim Haseltine]

Right, this is going to be a bit heavy on pictures.
Parked up last night in a position where I can work on the car, so I haven't moved it this morning.
There was oil in both pipes after 4 days and approx 200 miles.
Left side from turbo - you can see a track of oil.

And the intercooler:

Right side from turbo, again there's a track of oil.

Right side airbox to turbo, there's some oil but that's my fault... the inlet pipe itself is dry inside

The PCV valve is misting oil out of the airvent

#1 plug, sooty around the base but the electrode is clean, front 3 other plugs of the righthand bank are the same

I fitted a couple of plastic sleeves to the turbo pipes and after a couple of hours:
Left side:

Right:

So the next move was to get my scope out, no pictures from that as it can't do them. Tops of the 4 rh bank pistons have some carbon (over 110K miles so I'm not surprised) but are dry, the inlet to the turbo is different, immediately below where the PCV vent feeds in is a pool of oil which is overflowing into the front of the turbo. I'm going ahead to check the left side but I'm certain that I'll find the same there.

[c3nturi0n]

RH Turbo or both on it's way out?

Do you notice any oil in the exhaust?

[Jim Haseltine]

Other than the intermittent clouds of blue smoke on start up, no, no smoke from the exhaust. When it smokes, it smokes big time then nothing for a couple of days.
This isn't clear,

The black patch outlined in yellow is the pool of oil and the bit outlined in green is where it's draining into the turbo inlet.
I took the PCV valve apart, the diaphram in the top has a small slit in it just about where the PCV air vent is, so that's why it's misting oil.
The left bank of cylinders look worse than the right, very black and there was a suspicion of dampness. Didn't appear to be oil when I put a probe in a couple of them.
A little more oil appeared in the rh after I blew through the PCV pipe, so tomorrow I'm going to dig a bit deeper.

[Jim Haseltine]

Where the oil goes from the PCV separator I'm not clear on, but I think it drops into the RH rocker cover.

And that's where it's supposed to go. I washed out the PCV with some old petrol and a lot of rubbish came out - and I mean a lot.
Probably a waste if time as the diaphram is split so it'll have to be replaced. Tomorrow I'm going to try to remove the rest of the breather pipes and test the check valves.
Whether the PCV is the real cause of the oil in the pipes and the intermittent smoke remains to be seen.