EGR and intake manifold cleaning 3.0 V6 TDI

[Leoflavio]

Hi All,
Regarding the VAG 3.0 V6 TDI (as used across the VAG group- ie Audi, VW, etc) and getting to the EGR and intake manifolds....looks interesting doesn't it?
Mine is a high miler now and recently had to face the dreaded DPF blocked issue. Costly option for the replacement part, but that's not what this post is about.

My convoluted thought train tells me that a high mile heavy oiler must surely need a little intake manifold and EGR cleaning, especially after a DFP blockage - which would have forced ridiculous amounts of exhaust gas back into the system with all the relevant additional soot deposits etc.

Now here's my problem. Once I pop the engine cover I am faced with those twin banks and all the rest of the stuff that neatly fitted nicely snug in the centre of the V6. The bit that worries me is that covering all of the bits that I'd like to get to, are various pipes, including what looks like a cross flow link between the 2 diesel common rail fuel system.

In effect I would have to unplug and disconnect a whole heap of things to get to the EGR cooler etc as well as the intake manifolds.
Is this going to prove to be a step too far for me - as in will the fuel line re-pressurisation be a major issue if I was to go through the strip down.

Input greatly appreciated as I think it may be a job worth doing.

Intermittent fault codes that come up linked to this are:
P1545 Throttle valve control system : malfunction.
P0401 Exhaust gas recirculation flow: insufficient detected

I understand a blocked or clogged EGR valve can give 'insufficient detected' reading. The EGR enters the air intake system at the Throttle valve control and could therefore be clogging that up as well.

Best Regards.

[Crasher]

Lovely things to dive into aren’t they, makes you wonder why us spanner monkeys are held in such low esteem when we have to take things like that to pieces and put them back together doesn’t it? I use paint stripper to shift the heavy gunk after the scrapping is completed and then TFR for the final cleaning. It is disgusting work and you would be amazed how far that crap can travel, I have found it in various parts of my house, transferred on my shoes I assume.

[Leoflavio]

Hmmm, yes I am expecting it to be one of those moments - 'OMG how did all that manage to live in there'.
Yip, I usually just drive cars and have always viewed the internals with a heavy suspicion. A bit of Here Be Dragons methinks. However, a mate has been detuning my attitude about things like that and showing me that Dragons may not in fact exist.
The reason why I've popped up this post is that I'm a bit unsure about touching the fuel system (which I would have to do) if I am to get to the parts.
No go or should I have fun making gunge cakes?

[Crasher]

You need to equip yourself with parts system and workshop system diagrams specific to your car and take photo’s as you take it to pieces plus keep parts in groups with their specific fasteners, do not just pile all the nuts and bolts together or you will lose the will to live trying to work out where they all go. PM me your reg number and email and I will send you the diagrams.

[Leoflavio]

Thanks Crasher. PM sent and your offer greatly appreciated.

There isn't much available on the net regarding Phaetons so I think doing a photo run of the whole thing might be handy for everyone.
As I'm going through prep phase and making sure of what's what, I might add that the common rail link pipe etc doesn't seem so scary anymore. Handy to know that the fuel system auto purges itself afterwards.

[Leoflavio]

Well that was an interesting Sunday. Here's how my day went.
Woke up, looked at the car, felt a sense of panic so made a cup of coffee.
Looked at the car again, more panic and more coffee. Finally, looked at the car and opened the bonnet. Gulped and took off the engine cover.

Using the diagrams that CRASHER sent me I launched into strip down mode.
This was fairly straight forward, except for the odd bits that weren't listed on the diagrams. Not a panic though.

The intake manifold is split into 3 sections.
1) Top section is the split black plastic piping - pretty straight forward to remove, along with the throttle valve. (first bit of the strip down)
2) Lower section of left left hand manifold (while standing in front of the car looking into bay). Decided to leave this one as no fault codes on that one, though it was far more coked up than the other one. I'd say coked up about 3 times the rate of the right hand one.
3) The right hand lower section (fault codes) was fairly straight forward to remove though space is very tight all round one the top manifold section is removed. Just one bit that was a bas***d to get out of the way in order to remove the intake out of car - wasn't shown on diagram so wasn't expecting it either.

Relevant fault codes:
12597 P3135 Intake Manifold runner control: lower stop not reached
04120 P1018 Intake Manifold runner bank 2: lower limit not reached

Decided to focus on this area specifically. The unit (lower manifold section) includes the plastic manifold as well as the flap motor - which VW sells as one unit for horrendous amounts of money - paperwork says that the manifold and the motor must be changed together.

Anyway. Discovered that the play in the butterfly flaps was very severe compared to the other manifold. Focused most of my cleaning endevours on this manifold - did a fair bit on the rest as well - The bottom of the manifold, once you remove the rubber gasket, allows you to remove the butterfly flaps and the 6 grommets that hold it in place. After a bit of a clean up it was clear why there was so much play. The grommets were very worn - least worn at the motor end and wear increased as you went down the line to the point furthest away from the motor arm end. The butterfly flats themselves showed some serious wear one one side. Again, least nearest the motor arm and most at the furthest point away.

Took photos as I went - must just work out how to upload them to the forum and will add them soon as I can. Don't have any decent photo editors on this laptop.

Reassembled the lot, only this time swapped the grommets around so that the least wear was at the furthest point etc. This doesn't appear to be enough, but will have to act as a temp fix until I can replace correctly.

Checked out the EGR system and decided to leave that put for right now as dirt in there appeared minimal - dry powder and loose, easy off - not gummy at all. I guess the heat that it carries, even through the EGR cooler system is enough to keep it loose.
Can't say the same when it hits the fresh air flow. Mixes with oil residues etc and gums up nicely in the manifold a little way down.

I don't have VAG-COM so will have to wait till tomorrow or so to get the car plugged in again. I don't think the grommet swop is a long term solution, nor is it probably enough to kill the MIL, but I did it to get the car back on the road. After all, I have to drive it down the road to get plugged in.

[TheMatador]

Great post - thanks for sharing your experiences. I'm starting to see similar issues - intermittent intake manifold lower limit fault codes and now the EGR insufficient flow has popped up for the first time.

Any chance you could post or PM your pictures?

[TheMatador]

I've had both mine done now. 3-4 hours work for local mobile mechanic (NVS - recommended) plus parts.

Have posted pictures and a how-to from a polish A6 club here:

https://www.vwaudiforum.co.uk/forum/s...627#post567627