Decarbonisation for GTI Mk6 at 2 year service?

**fryad** · 05-03-2012, 12:24 PM

Hi all, I wonder if anyone can shed some light on this please?

My GTI went in for its 2 year service at Camberwell Volkswagen this morning with 24,000kms on the clock. They recommended a decarbonising service for $185. I declined.

Trying to find out what this actually IS, I found this thread on the forum: http://www.vwwatercooled.org.au/foru...ice-58037.html. While the thread discusses what the carbon build up is and that it affects DI engines only, there is not a definitive answer as to whether or not this needs to be done at all! Can someone please advise? A post by Corey makes sense suggesting that carbon build up won't affect performance at all.

Also, a UK forum post suggested that petrol additives can do the job for you. Is there a product in Australia that I could add to the fuel to help decarbonise the valves etc for a lot less than the crazy $185 I was quoted?

Thanks in advance for your help.

**Transporter** · 05-03-2012, 12:27 PM

You will not be able to remove the deposit from the valves in the DI engine. These deposits have impact on the performance, since it changes (restricts) the flow into the cylinders.

**Bora Sport** · 05-03-2012, 01:55 PM

I have no experience with DI engines however I can tell you that my local VW dealer has been trying to sell me this for the last 8 years and I personally think it is a blatant money grab. I pulled the head off my Vento at around 360,000k's when the cam belt broke and it bent a valve. I replaced the valve and put it back together without doing or replacing anything else (other than head studs and gaskets obviously) and it was still going strong 80,000k's later when my son wrote it off. My mechanic mate said at the time that there was no need to decarbon or clean/decoke the engine or valves at all as it was clean as. I always use 98 octane fuel. My Bora has 250,000k's on it now and runs just fine. These days with electroninc injection and management engines just don't carbon up the way they used to in the old carburettor days.

My 2 cent rant......

**Tim** · 05-03-2012, 02:02 PM

I would ask what is involved in their decarbon service.
It definately is a problem on direct injection engines and perhaps cleaning them before they become absolutely filthy is a good idea. Id just be asking which process they use to do it. Only then can you ascertain if it is a worthwhile expense or not.

**fryad** · 05-03-2012, 02:04 PM

I'm with you that I suspect it's a 'blatant money grab' so thanks for the 'rant'!

Maybe you're right and just using 98 octane everytime is enough? Thoughts....?

---------- Post added at 03:04 PM ---------- Previous post was at 03:03 PM ----------

Thanks Tim. Just got the car back and they said it's a spray they mist through the ports? No product name or anything. I'll email the service mgr and see what the response is.

**Tim** · 05-03-2012, 02:09 PM

Sounds similar to the Subaru upper engine cleaner sprays. If thats the case then its a pretty expensive can

**brad** · 06-03-2012, 02:29 PM

Originally Posted by Bora Sport

I have no experience with DI engines however I can tell you that my local VW dealer has been trying to sell me this for the last 8 years and I personally think it is a blatant money grab. I pulled the head off my Vento at around 360,000k's

Your Vento isn't Direct Injection, so you are correct as the fuel is injected before the valve & the solvent properties would help keep it relatively clean.

DI injects straight into the cylinder, therefore the inlet doesn't get any solvents & depending on driving style, PCV, etc you could get a fairly hefty build-up of carbon on the inlet.

Something like this:

**Greg Roles** · 06-03-2012, 05:05 PM

Spot on. Explain to me how a spray is going to remove baked on carbon, let alone a mm or two of gunge PCV/egr oily sludge mix.

Will help, and better than nothing, but you eiother ignore it, physically clean it, or get a catch can of some sort. Even that doesn't totally stop it.....even your turbo is a total oil loss bearing....

**rossw** · 09-03-2012, 01:07 PM

Since any carbon build up in a DI engine is going to be sourced from oil mist from the PCV or turbo bearing, surely the Very Expensive VW approved oil would be formulated to address this problem?

If it is an issue with MK6 golfs, I'd want to see some dismantling done for $185.

**Diesel_vert** · 05-03-2012, 03:17 PM

Originally Posted by fryad

Trying to find out what this actually IS, I found this thread on the forum: http://www.vwwatercooled.org.au/foru...ice-58037.html. While the thread discusses what the carbon build up is and that it affects DI engines only, there is not a definitive answer as to whether or not this needs to be done at all! Can someone please advise? A post by Corey makes sense suggesting that carbon build up won't affect performance at all.

It does affect performance, but the severity depends on the specific engine. For example, an Audi RS4 (4.2 V8 FSI) in a worst case scenario, lost up to 40 HP (30 kW).

Related article: "Direct Injection Fouls Some Early Adopters"

Originally Posted by fryad

Also, a UK forum post suggested that petrol additives can do the job for you. Is there a product in Australia that I could add to the fuel to help decarbonise the valves etc for a lot less than the crazy $185 I was quoted?

$185 is good value if it includes labour costs for taking the valves out of the engine and cleaning them, not so much if they just pour it in the engine.

Originally Posted by fryad

Maybe you're right and just using 98 octane everytime is enough? Thoughts....?

Same deal as above. Whatever the grade of fuel and its additives, it won't do much to prevent carbon buildup, unfortunately .