Water Spray into Running Engine?

23 Sep 2010
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We have an engine that chokes up with carbon, its a diesel and difficult to know why. I should really post this in Motoring, but was afraid someone would try this on their car.

"So don't try this at home"

Apparently if you spray a mist of water (Mr Muscle bottle) into the inlet manifold while the engine is running, this will take the carbon off the internal parts?


My first reaction was to think it was an easy way to wreck a good engine, by locking it solid against the water (hydrolock).

But, seemingly it will work just as well on the 2-stroke garden engines? Anyone know if it actually works?
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7 Feb 2008
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United Kingdom
Its a fairly curious thing to do, but so long as the water spray is very fine, there won't be a hydraulic lock.....I think its actually the effect of the water turning to steam that has the most cleansing benefit!
I have noticed on one motor that I took apart that had a slight head gasket weep - the top of the piston was very clean, but of course that happened over a certain period of time.
Water injection has actually been tested before, but I don't know what the outcome was...presumably not too good as the major manufacturers would be using it if there was anything to be gained.
I'll leave you to be the test guinea pig! :p
John :)

I'll just edit that one.....with a two stroke engine, the fuel / oil mix also lubes the main and big / small end bearings - I don't think they'd appreciate a splash of water, but there again, a little bit would do no harm.
For a 2 stroke, pop the exhaust muffler off, and decoke the exhaust port - thats all you need. If its really bad, the muffler is likely to be full too so its out with the blow torch.
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