[VaSteve]

I was talking about this with a Dorki the other night...has anyone here tried to decarbonize the engine by pouring a little water into it? What were the results like?

[rs911t]

Search Pelican - lots of talk on this subject a while back. I gave it a half-hearted try. Felt rather funny dribbling water into the carbs. Nothing happened. The proper procedure apparently involves high RPM and a surprising amount of water.

[William Miller]

I've done it in the past with great sucess, but not on the SC. This was on early cars my 1970 Grand Prix, 63 e-type and a 67 bug. It's amazing the stuff that came out of the tailpipe. BTW, no cats to worry about.
I've seen this posted before and I've always wondered if it was a bad thing for Oxigen sensor and the cat.
Someone here will chime in.

[William Miller]

Greg's right, on a small block you can use a garden hose turned on lightly and not kill the engine. Every year I winterize the boat engine. After the oil change and running some Sta-bil in the carbs you spray the contents of a spray can into the carb until it kills the engine. If you raise it above idle it won't die.

Now that you brought it up, doing the water treatment in the spring might be a good idea. I usually do the first start on land with the hose hook up.
Don't really want to dump all that crap in the bay.

[Trak Ratt]

Used this method for years. Works best when sprayed as direct as possible into the inlet. The way I was taught by “roundy round” mechs is to use a spray bottle of water, engine at about 3K, spray water until engine starts to stall. Back off then repeat, a lot. I wouldn’t use a hose, water doesn’t compress and I would fear getting to much concentrated during the compression stroke. If serious, I would do it just before changing the oil because you do want to use a lot of water (spray)

It’s the water droplets, moving fast in the air/fuel mixture that cleans the valves, pistons, plugs and to some extend the intakes.

I’ve heard of engines that have sat for a while actually bending connecting rods when enough water collects on top of the pistons. And that’s just with the starter motor! If you use after market air filters that mount directly over carbs or injectors like “Rain Guards”. Make sure the rubber grommets are in place on the mounting studs or rain can actually leak down from the top cover. I learned this the hard way, though no damage it’s tedious to have to remove the spark plugs and pump out the cylinders

[William Miller]

Same problem happens on boat engines when the water cooled exhaust manifolds rust thru. The water jacket rusts into the manfold side and water fills up the cylinder.

This happened to me after an exteded day fishing in the ocean. Luckily I was inshore and only about a mile from the marina. I slowed down off plane, the engine quit and would not turn over because of the hydrolic lock.

Also lucky was that it was the same time the charter fleet was comming back in. I got a quick tow back in.

I really didn't know what happened untill I pulled the head and manifold.

What did happen was the manifold was not only rusted thru, but was partially blocked. When I slowed down the engine heated up, coughed and ran backwards for a second, sucking the water in the exhaust valve.

I was lucky nothing on the bottom end got bent and used the oppertunity for a valve job (Since I was in there!) Once back together it ran better than ever!

Salt water is a bitch on Iron!

[William Miller]

David, I forgot to ask again, what effect if any will this have on the O2 sensor and cat?

[Trak Ratt]

Hadn’t given the effect on O2 sensor or cat much thought. But any water going down stream would be vapor by the time it got to O2 or cat. Both live through countless heat cycles on startup so probably nothing. I guess at the extreme; O2 sensor runs cooler so engine management richens mixture. Cat uses heat generation to “burn off” pollutants so lower operating temperatures means more pollutants during testing.

Course in the extreme, extreme; H2 separates from O, builds concentration in cat, heat ignites mixture…. car goes boom like grenaded grass shack in Rambo movie

[William Miller]

My thought was that all the carbon crap that flakes off would possibly clog things up!

[Trak Ratt]

Originally Posted by William Miller

My thought was that all the carbon crap that flakes off would possibly clog things up!

Cat uses heat generation to “burn off” pollutants