[Watsey]

My car has gone past 80,000 miles and I've had a de-coke on the list of things to do for a while. I tried a couple of can of EGR cleaner (STP and Wynns) but decided not to try and get the inlet manifold off the car as I've not done this before. This means that I don't have any 'before' photos as a record of how much soot/carbon/sludge was there before any cleaners were used.

I haven't really noticed any significant differences as a result of using these aerosol cleaners, but the Wynns was definitely the kinder of the two to the engine (the STP had to be used very carefully so as to avoid any knocking).

I booked the car with Autowerx (Milton Keynes) for walnut blasting of the inlet ports and also for the inlet manifold to be cleaned while it was off the car. The inlet manifold cannot be split, so it was a case of using a carbon-dissolving gel sprayed into the inlet manifold through all openings and using best endeavours.

You can see the amount of build-up in the photos. Interestingly, cylinder ports 1-3 were a lot 'wetter' with oily deposits compared to ports 4-6 which were only sooty and also less fouled. Perhaps the oil droplets, being heavier, were less likely to be drawn along the length of the inlet manifold.

The inlet manifold ports and butterflies were quite heavily caked. It was about what I'd expected to see : not blocked, but still quite heavy deposits. Just goes to show that even with premium fuel, fuel additives, and regular use of concentrated cylinder/EGR/DPF cleaners that EGR systems fundamentally recirculate a lot of contaminants back to the inlet side of the combustion process, and this shit sticks to everything.

The intercooler was also removed at the same time - completely clear; just a few drops of water as a result of some condensation.

There's a useful, but not night and day, improvement in refinement and pull from the engine. I'll be keeping en eye on fuel consumption as I expect this to improve as a result of the cleaner inlet tract.

[Tengocity]

Thanks Watsey, I'd been looking at this and the other method for my 335d and looks like it would have been well worth it.

Maybe something to look in to for the Boxster.

[Turbonut]

Interesting post, and i'm surprised at the amount of build up after 80k miles. I was also thinking of having similar work done myself, as my car is also around the same mileage, and I have used premium fuel throughtout my ownership.

Mind if I ask roughly what the bill was and how long it took to do the work? I work a lot in London so I could leave the car with them for a couple of days.

[Watsey]

I don't like to post pricing as it's their business, but let's say I thought it was very reasonable. Autowerx also ran a diagnostic on the car and seemed to have resolved what causing a chassis warning light, and only added 1/2 labour to the bill. Most places simply state a flat fee for diagnostics and I've seen £90 quoted.

If you left your car with them for a couple of days they could probably soak the inlet manifold overnight to give a deep clean. I wanted to do that but time was short.

[RoShambolt]

I've used Autowerx for their body shop side, very reasonably priced and insane quality of work, and I'm a fussy fucker. Good guys there.
They do a lot of classic Porsche work and some serious restoration work too. Good to hear their maintenance side is just as good.

[Wills2]

Jesus that was filthy before the clean, wow.

[Ajs_435d]

Interesting, thanks for posting not surprised to be honest.

No amount of snakeoil or products will make a meaningful difference to this build up, its a byproduct of seals, bearings, turbo and blowby albeit made worse by dpf filters/Egr and small channels that increase build up.

Walnut blasting and good old sitting in cleaning fluids is definetly way to forward these terracleans etc simply don't clean the most troublesome areas.

[ian332isport]

Originally Posted by Ajs_435d

Walnut blasting and good old sitting in cleaning fluids is definetly way to forward these terracleans etc simply don't clean the most troublesome areas.

Agreed.

Terraclean (or fancy fuel) is never going to clean out the manifold or any of the really gunky bits on a modern common rail diesel. It only enters the engine through the injectors, so is already downstream of all this filth. I'm sure it does a lovely job on the injectors, and possibly the combustion chambers, but apart from that it's of little use.

[Watsey]

Originally Posted by Ajs_435d

Interesting, thanks for posting not surprised to be honest.

No amount of snakeoil or products will make a meaningful difference to this build up, its a byproduct of seals, bearings, turbo and blowby albeit made worse by dpf filters/Egr and small channels that increase build up.

Walnut blasting and good old sitting in cleaning fluids is definetly way to forward these terracleans etc simply don't clean the most troublesome areas.

Agreed. Would never both with Terraclean but thought an EGR/manifold cleaner was worth a try. Clearly they don't have a significant cleaning action on big deposits.

[Neilb76]

This is the same problem I had on the RS4. Lost near 30hp due to the carbon build up to the valves and inlet manifold. Sent it to MRC basically shot blast it with crushed wall nuts in believe. So had the stage 2 inlet clean and deflpped etc plus a few other bits done and it made 444hp again.

The Terra clean will not really do anything it needs a proper clean. Plenty videos on carbon build up best to look at the RS4 videos as they are known to suffer badly..