Engine Decarbon Service

[Stevie1]

Hi all,

What specifically is as the title reads? It was recommended to me today during my 2year service as i did not not know exactly what it was and the ramifications for not going ahead i held back when the dealer service dept recommended it. I questioned if it was required why it is not part of the routine service anyways. The dealer responded that it was usually an extra they they recommended.

Anyways who can enlighten me please? The car is a GTI DSG MY09 with 19,500 klm., and the price was $185, sound like the right price?


Thanks in advance.

[break]

That sounds horribly expensive.

Decarbonation (I'm not sure if that's a real word ) is the process of removing carbon deposits (and other gunk) on the upper engine (so intake runners, valves, pistons, cylinder walls.

This is particularly important in the 2.0T VAG motors as they are all direct injection motors, and fuel that would normally spray onto the intake valve to clean it is instead being sprayed directly into the motor ( non-direct injected motors have their injectors pointing at the rear of the intake valve to help clean it).

As such, the intake valves can get VERY dirty. This is even more serious as the 2.0T VAG motors all breath oil vapors into the intake, causing this oily residue to build up on the intake valves.

Decarbonation is usually done in a spray can form (I use the 'Subaru Upper Engine Cleaner', available from any Subaru spare parts dealer for ~$20), which needs to be sprayed into the intake plenum AFTER the throttle body as per the directions on the can. This mixture is part alcohol, part water, part petrol... and it causes a cleaning affect that will remove deposits from all the engine components previously listed.

It's a simple process to do yourself if you have a friend handy to help.

Steps are:

* Locate vacuum line from the plenum, unplug it and spray the mixture into the plenum as directed (typically 1/2 a can needs to be sprayed in)
* Let the car sit for 5-10mins for the mixture to clean the valves
* Get a friend to start the car (it will be tough to start the first time)
* Carefully spray the rest of the mixture into the plenum as a friend holds the car slightly above idle to avoid the car stalling

NOTE: Don't be alarmed during this process, but there WILL be copious amounts of white smoke pouring out of your exhaust. This is a result of the high water content in the mixture.

* Once the can has been emptied, turn the car off and let it sit for 5-10mins while you reconnect the vacuum line to the plenum.
* Turn the car back on and go for a drive, and drive the car HARD (once it's warmed up, of course). You want to dislodge any remaining carbon/residue in this process, so take the engine through its entire rev range (up to near redline) while under full throttle. Do this for 5-10mins, then drive the car very carefully for 5-10mins to let it cool down before returning home.

Hope that helps

[Stevie1]

Thanks Break.

So are you telling me i need to do it, however the price that i've been quoted sounds too rich.

I don't have the expertise to do it, so it may come down to someone else servicing it for me.

Anyone recommend someone in Melbourne's eastern suburbs?

[whiteVR6]

This process does very little in the scheme of things. Physically removing the intake manifold and hand cleaning the intake, valves etc is really the correct way of doing it.

[Corey_R]

That'll cost you a lot more than $185 though

[noisuf]

That sounds horribly expensive.
* Locate vacuum line from the plenum, unplug it and spray the mixture into the plenum as directed (typically 1/2 a can needs to be sprayed in)
Hope that helps

Does anyone have a picture of where the vacuum line from the plenum may be for the MKV R32?

[NabzGTI]

Hi all,

What specifically is as the title reads? It was recommended to me today during my 2year service as i did not not know exactly what it was and the ramifications for not going ahead i held back when the dealer service dept recommended it. I questioned if it was required why it is not part of the routine service anyways. The dealer responded that it was usually an extra they they recommended.

Anyways who can enlighten me please? The car is a GTI DSG MY09 with 19,500 klm., and the price was $185, sound like the right price?


Thanks in advance.

Dont waste your money on that type of decarbon. Take WhiteVR6's advise and do it properly. You're better off spending that $185 on a catch can solution.

[Transporter]

It depends how long you want to keep that car, if you'd sell it before 60,000-80,000km don't worry about it too much.

But even ordinary Nulon TB cleaner when sprayed into the intake give this result.
Before


After


So, there is definitely some benefit.

[gh172]

That sounds horribly expensive.

Decarbonation (I'm not sure if that's a real word ) is the process of removing carbon deposits (and other gunk) on the upper engine (so intake runners, valves, pistons, cylinder walls.

This is particularly important in the 2.0T VAG motors as they are all direct injection motors, and fuel that would normally spray onto the intake valve to clean it is instead being sprayed directly into the motor ( non-direct injected motors have their injectors pointing at the rear of the intake valve to help clean it).

As such, the intake valves can get VERY dirty. This is even more serious as the 2.0T VAG motors all breath oil vapors into the intake, causing this oily residue to build up on the intake valves.

Decarbonation is usually done in a spray can form (I use the 'Subaru Upper Engine Cleaner', available from any Subaru spare parts dealer for ~$20), which needs to be sprayed into the intake plenum AFTER the throttle body as per the directions on the can. This mixture is part alcohol, part water, part petrol... and it causes a cleaning affect that will remove deposits from all the engine components previously listed.

It's a simple process to do yourself if you have a friend handy to help.

Steps are:

* Locate vacuum line from the plenum, unplug it and spray the mixture into the plenum as directed (typically 1/2 a can needs to be sprayed in)
* Let the car sit for 5-10mins for the mixture to clean the valves
* Get a friend to start the car (it will be tough to start the first time)
* Carefully spray the rest of the mixture into the plenum as a friend holds the car slightly above idle to avoid the car stalling

NOTE: Don't be alarmed during this process, but there WILL be copious amounts of white smoke pouring out of your exhaust. This is a result of the high water content in the mixture.

* Once the can has been emptied, turn the car off and let it sit for 5-10mins while you reconnect the vacuum line to the plenum.
* Turn the car back on and go for a drive, and drive the car HARD (once it's warmed up, of course). You want to dislodge any remaining carbon/residue in this process, so take the engine through its entire rev range (up to near redline) while under full throttle. Do this for 5-10mins, then drive the car very carefully for 5-10mins to let it cool down before returning home.

Hope that helps

At the risk of asking what may sound like a dumb question, where exactly is the vacuum line that connects to the plenum located?

[break]

This process does very little in the scheme of things. Physically removing the intake manifold and hand cleaning the intake, valves etc is really the correct way of doing it.

It entirely depends on how long you've left it. If you do this process every 15-20k then you'll never need to pull the manifold and scrub it down. If it's been 80-100k+ then it may be a better option to take the plenum off entirely, as you suggest.

At the risk of asking what may sound like a dumb question, where exactly is the vacuum line that connects to the plenum located?

I don't have a MKV Golf GTI so I can't say, but if someone puts up a picture of the motor with the engine cover off i'll point it out for you.