thomas1

Ok here is my story, my Mother in Law car which is a 1995 Camry/2.2liter with 199k miles was due for smog. Last smog was performed in 2013 and squeeked by with max on HC and CO very close to limit.
%CO2, O2, HC , CO , NO
13.3 , 1.4 , 60 , .30 , 401
So I take car to my son in laws brothers shop and the mechanic says yup the cat is not working. Mind you I changed the plugs, pcv, and oil. He says it will pass after I clean the converter. So he hooks bottle of water thru a valve to intake and runs engine at 4000 rpm and adjust water intake to just make engine missfire and backs off. runs it for 10 minutes and then tells me the fuel trims will be off, drive it down the road for a couple of miles and than we tested it. Wow!!!!!
% co2, O2, HC, CO, NO
15.1, 0.00, 15, .05, 45


Basically this high mileage car had oil leakage past valve stem seals and cat was contaminated with oil residue. The Water Steam cleaned the cat and washed oil out the tail pipe....Saved me $800 for a new cat and car runs like a top. I have worked on cars all my life and I just learned something new. He said you could do same thing at home, but have to control that water flow with a clamp and make sure to not hydrolock the engine. I am still not to old to learn but it made my day as smog has always been a issue with my mother in laws cars as they are old and high mileage. kudos to this man for helping me

kalali

My old Jeep Cherokee gets that water treatment once a year, 12 oz bottle..... Didn't know about the affect on the cat but it supposedly cleans/burns carbon off the valve surfaces and stems as well as piston tops. I use the hose from brake booster to the intake manifold and engine vacuum sucks the water in.

thomas1

Yea a win win no mater what you are trying to accomplish...

salimshah

I have seen such treatment to remove the carbon build up in the head and valves.

Before readers in this forum quickly try to do this, let me caution them that

a) too much water will cause permanent engine damage. Air is compressible, but water is not and during a compression stroke, the volume of water and air may not be compressible beyond capacity and then you can get serious damage. [Never ever do this with diesel engine, even a small amount of water will be bad]

b) too little water, wont work.

c) rust. [clarification: Rust before we get into the chamber (intake plenum area), there is plenty of water (steam) due to combustion of hydrocarbon]

I would suggest that the process be not tried by a novice or if you do, think of possible outcome.

In Thomas' case, I would have opted to remove the cat and give it a steam bath out side of the engine. How easy would it have been without the compressed and hot exhaust? I really dont know.

Finally, it ended well for both the posters. Good for them, but novices, tread with caution.

Salim

fastnoypi

a hard highway drive till the exhaust is hot will accomplish the same thing to "clean" the cats. Unfortunately racing around may draw unwanted attention from your local PD.

As far as using water for a top end cleaning, do this with an engine that has already reached normal operating temp. The object is to create steam off the back of the valves and piston faces. A top end cleaner like seafoam may be safer to use for someone with less experience. As the seafoam will evaporate eventually in the event of accidentally killing your spark.

IMO rust is not much of a concern since an oil mist will always be in the intake track from normal PCV operation.

fwiw, I have used an 50/50 methanol and water injection system in my other car for years, when i removed the heads for a valve job, everything including the piston tops were free of excess carbon and no signs of rust at all.

thomas1

Note: I also posted this on the Toyota Nation site and the response has been interesting. Several members have solved issues with this procedure. Much cleaner than using seafoam, etc. I personally am still astounded at the reduction in emissions. tells me that a lot of converters are replaced every year with precious metals when not needed. And yes you have to be careful....