de-carbonising ? anyone tried this?

[SKnibbs]

Hello Everyone

I wonder what your thoughts are on de-carbonising (applied to any modern diesel or TDi) ? Has anyone doen this and can speak from experience? I own a B7 tdi 140 Avant (a4), but its a general question really.....

There are many threads on the internet and youtube where seasoned mechanics say its a great thing to clean out many parts of a TDi engine - the process the describe is simply warm the vehicle up to normal operating temps, then keep it idling, remove the air filter hose and spray normal tap water into the hose (after the MAF) , using a spray bottle with one squirt, wait a few seconds, squirt again and repeat for until you have used approx a coffee cup worth of water. Using a spray prevents hydro lockinhg the eingien due to too much water too fast.

My question is - is this safe ? Many people comment on the videos saying its madness and just asking for trouble. Yet the mechanics who do it say they have done it hundreds of times for customers cars and swear by it as a great free tune up for any car (diesel and petrol).

I would be very interested to see what the general consensus on this forum is?

Many thanks, eagerly awaiting your opinions or experiences.....

thank you

[SKnibbs]

Hi

Further to my above post - is there any reason to use special sprays specifically for this purpose (Wynns etc) or does the water spray work just as well?

And I wanted to ask - when you do spray into the air filter hose, whatever carbon or debris is loosened , where does this go? Does it go out the exhaust (which would be great ) or does it go via the engine and oil and then out the exhaust? I am mechanically a novice so please excuse if I this question is really silly? Its just I have read other peoples opinions suggesting doing this whole de-carbonising process is the equivalent of opening up your engine oil refill hole and throuwing in dust and debris into it? Is this really what happens to the loosened carbon?

thanks !

[zollaf]

best not to try this... yes water will wash carbon off, you only need to remove a cylinder head from an engine thats had a leaking head gasket to see that affect, but it wont do anything to the carbon in the intake or egr valve which is where it matters. too much water and you end up with a bent rod which will ruin an otherwise good day. oh, and it doesnt take much water to bend a rod, especially in a diesel engine with a high compression ratio. if you wish to remove carbon, first remove the inlet manifold and start cleaning.

[SKnibbs]

Thank you Zollaf

ok so what about the Wynns product that is specifically desgined to spray into the air filter hose whilst engine idling - have you tried this before? any chance of damage to engine?

anyones view is welcome thanks.......

[zollaf]

i refer to my last sentence... the one about removing stuff and cleaning by hand. when you have done this you soon realise that nothing you spray into your car will do a better job..

[SKnibbs]

understood, thanks for that Zollaf. I wont attempt these spray techniques.

have a good weekend!

[zollaf]

its just not worth wasting your money on them , and i dont like to see people waste money on snake oil.

[Skezza]

best not to try this... yes water will wash carbon off, you only need to remove a cylinder head from an engine thats had a leaking head gasket to see that affect, but it wont do anything to the carbon in the intake or egr valve which is where it matters. too much water and you end up with a bent rod which will ruin an otherwise good day. oh, and it doesnt take much water to bend a rod, especially in a diesel engine with a high compression ratio. if you wish to remove carbon, first remove the inlet manifold and start cleaning.

Totally agree about the carbon on the intake manifold being where it matters. I did it on a Lupo and it was caked so thick it took a huge amount of effort to get it clean. That said, I thought it took a fair amount of water (Especially in spray form) to bend a rod. Aren't water injection what they used in World War 2 planes ?

[zollaf]

water injection is used in high performance turbo'd petrol cars. it is sprayed in in a fine mist and cools the charge air. using it means you can run more boost without detonation. it usually comes on at wot (wide open throttle).
a diesel runs a lot more compression. add water as well as the fuel to the charge air and at tdc compression the volume of the combustion chamber is reduced. reduce it too much and bang goes a rod. the amount of water which is too much really isnt much at all, not with a 22:1 compression ratio. i wouldnt want to find out myself, hate destroying engines. a petrol engine is much more tolerant though.

[Skezza]

water injection is used in high performance turbo'd petrol cars. it is sprayed in in a fine mist and cools the charge air. using it means you can run more boost without detonation. it usually comes on at wot (wide open throttle).
a diesel runs a lot more compression. add water as well as the fuel to the charge air and at tdc compression the volume of the combustion chamber is reduced. reduce it too much and bang goes a rod. the amount of water which is too much really isnt much at all, not with a 22:1 compression ratio. i wouldnt want to find out myself, hate destroying engines. a petrol engine is much more tolerant though.

Interesting. What would be the benefits of running on a petrol though?