Answer

Hi.

Its not the method of cleaning out carbon deposits if i asume your going to pouring water down in the cylinders without the head being removed.which would be unadvisable.. as most of the carbon deposits won't even get passed the rings round the pistons to drain into the sump..there are additives in local motor factors that can help reduce deposits like Redex in a blue bottle to increase diesel octane so the it burns hotter to burn off most of the deposits in the cylinders.Or Forte Diesel Treatment.they should also do a engine flush which you add to the old oil to help clean out deposits where then you drain of the oil after it done it job. then re-new oil.

The other option but not normally done now on modern cars is to removed the head/valves and clean the hard carbon and deposits out that way and any associated parts like EGR valves etc.. but i certainly would'nt go pouring water straight into the engine.

Edited by Rob on 8/18/2009 at 2:53 PM

Expert:	Rob
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Answered:	8/18/2009

UK Car Mechanic

Self Employed in Motortrade/Garage Owner