Hitchcocks Forum

De coking by means of a water spray in to the inlet came up some while back. I was thinking of giving it a go, perhaps using a plant spray. Does this sound like a good idea? Any tips or comments?

Do people de-coke engines these days?

Burns a bit of oil, probably a bit sooty.

I am at a loss to understand what on earth a water spray would do to decoke an engine. People at various times have experimented with water injection to get a heavier charge and hopefully more power from an engine. The results have in the main bee a little inconclusive. Except for the formation of serious corrosion inside the engine, particularly on iron barrels and or heads. Valves are also affected along with rockers and bearings. So perhaps somebody could explain the water imjection decoking theory to this old engineer who at this time remains completely sceptical.

Hi guys--------- During my time with HM-RN, a gas turbine engines' compressor-turbine blades were "de-coked" by Carbo-Blast...This consisted of chucking a bucket load of crushed walnut shells into the air inlet ducting whilst the engine was on a fast idle.......They would impinge on the blading thus cleaning any bits of debris attached......A "Water-wash" then followed with a bucket or two of CLEAN water being thrown in...... In both cases the resulting residue was instantly burnt to a vapour in the power turbine / combustion chamber.....I kid you not, chaps !!!

------------ have just been doing some research on this one.... Apparently, with the engine at HOT temp and running at a fast idle, you spray a fine water mist directly into the carb mouth...The O2 content helps burn-off the carbon............

i may give it a try. I'll lay off the walnut shells, though. The steam injection for a heavier charge is a different thing.

Not sure passing water through the carb is such a good idea if the fuel contains ethanol. Liable to emulsify and block the jets. A dose of Redex down the plug hole and left overnight might have the desired effect. If it works you may well find oil consumption increases, as the carbon may actually be helping to create a seal.

Alan that water spray idea sounds a bit like converting base metals to gold.....every alchemists dream. How do they separate the oxygen content from the compound known as H2O ? If scientist could do that then there would be no impending fuel crisis, because the remining separated out Hydrogen could be used to produce all the energy we need for our vehicles. What do I know? Decoke JohnR......IMHO simply whip the head off and do it properly.

Had reason to suspect head gasket leakage on a volvo and an old Ford. Both were loosing coolant water with no apparent leaks from hoses or rads. Sure enough on removal of the heads it was obvious water had been leaking into one cylinder of each engine.

Also blatantly obvious was the piston in each offending cylinder was steam cleaned to bright alloy, unlike the others which still had the coating of brown/black carbon… So yes water works as a decarboniser.. Question is, how much water? and how long for?

Single cylinder motor may be problematic to keep running during application through the air intake, unlike multi pots which usually have at least one cylinder firing keeping the crank turning through misfires… As has been said water getting into the float bowl may create more problems then are being solved..

Perhaps using the redundant PAV stub on the intake manifold if still on a micarb may work with a tube leading to a water bottle controlled by squeezing the tube between finger and thumb…..

Have to say i'd prefer Redex in the plug hole and petrol tank,

Or maybe the american Sea Foam which is supposed to be good…

However depends if your suffering pre ignition or run on (dieseling) than a strip down and clean/check would be a pleasant way to spend an afternoon.. Better than shopping anyway..

cheers gwilly.