decarbonizing//guys at work
 

this is ine of those " the guys at work said..." anywhow this is what i heard. a simple, free procedure to decarbonize combustion chamber/valves is to have engine running above idle, say 2000 rpm while spraying a fine mist of water into the intake manifold. maybe for 5, 10 or 20 minutes. any credibility to this claim?

Uh...yeah. Go ahead and do it. Just remember to update me on how it goes.

brookspw

the question is, how fine a spray of water? you don't want to run your garden hose into the intake manifold with that mist setting if that's what you're thinking. water injection used to be a somewhat popular "mod". i don't see the kits around anymore - must be a reason why they fell out of favor...

Sure is. **BUT** I would hesitate to do it with my Benz. Check with a MB certified technician to see if there is recommended top end cleaner or another method.

I've never done it with a "modern" car, but I did the following on
my '70 Olds last summer, with the 400HP 455ci, hi compression motor (10.25:1).

This is the recipe I followed and it worked great.

GM recommended, (not widely disseminated info.) a mixture of 8 oz. of water and 8 oz. of brake fluid=1 pint total. Shaken well to blend mixture. Use a 16 oz. bottle. With engine at operating temp., pour liquid slowly into carb opening (through both primaries and secondaries) with engine RPM @ 1,000 to 1,200 or to *just* keep engine running. When there is approximately 4 to 6 oz. left in bottle, quickly pour the rest out and decrease revs so engine will die. Let stand for 15 mins. and fire up engine and idle at 1,000 RPMs. When engine idles smooth, drive car for about 10 miles at 60-70 mph. The reason you pour the last 4 or 6 oz. and kill the engine is for the solution to soften any of the carbon that is really hard that wasn't initially burnt off. It was common for lower compression engines and "babied" cars to load up with carbon back in the early 1960's and early '70s with leaded fuel.

The resulting detonation is said to knock the deposits free. I guess the "fine spray" is to ensure you don't hydrolock the engine.

Would I do it? Not on your life. Why bother? Have you seen the piston tops of high mileage MB engines that have lived on modern no-lead fuels? Since the mid '80's, carbon build up has not been any kind of a problem on MB engines. Any I've seen apart have been pretty clean.

A very wise person once said "If it ain't broke, don't fix it." This would be one of those times to heed that advice.

This practice of pouring water (or other liquid) in the intake manifold is exactly the key to acheive what is called ''liquid lock''.
if the liquid is not vaporized and remains in a liquid form when it reaches the combustion chamber, your have one of the following result:
1) Hole is a piston,
2) bent connecting rod
3) leaking head gasket.
4) bent cylinder head.
These are all big $$$$ to fix.
Don't try this at home.
JackD

Jackd is right on with this. A close friend who had a 77 280SE wanted to clean his engine this way. He mistakenly poured enough liquid into the intake and it bent a connecting rod. The reason was that liquids, unlike gases do not compress.

In my past automotive life, this procedure was only done when the mixture was assured to be of a very fine mist, a vapor really.

My 2 cents

I saw this done quite a bit in the sixties and seventies when high compression engines were driven by little old ladies and carboned up badly.

There are TWO risks with this:

You MIGHT break off a piece of carbon that lodges uder a valve or does damage in some other way.

You might get too much water in a cylinder. Remember water does NOT compress.

I personally would not try this old trick on any of my cars. I wouldn't even do it with my 25 year old farm truck.

Good luck,

i have heard it works very well, but there are 2 things to consider.
1. is there any carbon in there?? and if there is does it matter?
2. what are the chances of screwing it up?
i dunno about #2 it is very hard to hydrolock a rotary

mike
69 280s
59 tr-3a
72 r100
2x 85 rx-7's
88 rx-7 3 rotor
93 rx-7

Listen to ME. I just had my engine decarbonized at my local MB indy shop. He was changing my fuel injectors, as well. I had brought it in because I thought I needed new valve seals --- it was using 1 qt per 600 miles. He said, no, I needed a full valve job -- well, I vetoed that.

He called while doing the injectors and recommended the decarbonization. Well, I didn't even know what it was -- but he explained it (not the water, but another solution) and I okayed it.

Well, the car runs like a dream now AND I DON'T USE ANY OIL AT ALL!!!! Evidently, it wasn't the seals. But maybe a oil ring, etc., that was blocked or didn't fully engage because of carbon buildup. Anyway, I am sold on this.

brookspw

carbon buildup
 

Man,

I wouldnt do that. Not to my benz. If I did that to my diesel it would kill it. I havent ever done that. Usually the best way to burn off the carbon is to drive 10 miles at 4000 rpm or so. If you do the water trick, let us know how it goes.

I would use a humidifier if I was to do it. An ultrasonic one is probably the best, but dont saturate your air filter with water.

Austin

water injection is old hat.many of the second world war fighter planes used water injection for improved performance.as far as cleaning the engine If you just apply a fine mist for awhile,It can do no more than help.

I agree this is something that can ruin an engine if done too aggressively. But with a disciplined hand it can clean out an old engine.

The premise is the same as what you find with a leaky head gasket....when coolant gets into the cylinders, one symptom is a clean combustion chamber (or clean spark plug). The water "steam cleans" the chamber, resulting in a cleaner engine.

an engine must pick up some water while driving in the rain ,we used to run engines with no air filters in the fifties probably why we had to keep rebuilding them so often.......
William Rogers.......

what about using "steam" from a boiling kettle hooked up to a hose or something, or one of those "spitmaster" vapourizers that create steam qwithout the heat