We need to separate out what we're cleaning here.
There's combustion chamber cleaning and there's crankcase cleaning.
One is done through the intake system, the other through the oil filler cap.

 

who, what, why???????? yeah you can also bore out your cylinders buy putting sand in the intake....

 

It's an old mechanic's method for removing carbon from the combustion chamber. No big deal or cause for alarm. I've done it for years before the good chemical stuff was around.

 

the modern engines have extremely tight clearances. Yes even the 4.0. Back in the day early 80s and older engines, the clearances were like the grand cavern in comparison. They could handle the "old school" tricks no problems or questions asked.

Most of the Volvos I work on the clearances are so tight that if the engine looses oil pressure, even for an instance, you have MAJOR problems mechanically.

Having built both modern 4.0 and other modern engines before, and a lot of very old engines, I speak from experience that water or even watering down the oil with additives is an awful idea.

Best way to clean a crankcase, with out chemicals is simply run a high detergent (Pennzoil makes some good stuff) or run a lighter weight oil for a bout 500 miles, drain and refill with normal weight.

For intake and combustion, I prefer BG products, but sea foam works good also. Using water, and I understand the theory of it -- will only give you a high risk of damage. If you want to put something through your intake like water, but is MUCH SAFER. Use rubbing alcohol and a compressed air atomizer to mist it.

Most of the time, with modern engine oil and the additives it already has in it, it is pointless to have to clean a crankcase. Sludge just doesn't happen if you use the proper weight, a good brand (no elcheapo), and change the oil every 3000 miles.

 

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The SAFE WAY?
Change your frequently with GOOD oil.
And put TECHRON in the tank.

oil deposits will dissolve, and the carbon will SAFELY burn off.

Water, sea crap, in the intake, gas or strange stuff in the crankcase etc is not safe!

 

While I agree with the use of BG products, and I do use them, I disagree about the tolerances of the 4.0 motor and don't see how it is even applicable to this discussion. I'll bet if you looked up main, rod, and cam bearing clearances, piston clearances, ring end gaps etc for a 1970s AMC 258 six cylinder, you would find the tolerances are the same between the two engines.

 

Agree! No significant change sine the 50's. Maybe compared to the 30's?

The only change i can think of is cam lobes conform to tighter tolerances when ground - better control of valve timing for emissions.

Even crank and cam end plays are the same.

But - quench areas have changed - for the better.

 

Piston powered aircraft have used water/alcohol injection as a means to prevent detonation while operating at high manifold pressures such as during takeoff. The water is injected in precisely metered amounts. IIRC, the ADI (anti-detonation injection) was used at power settings above METO (maximum except takeoff). Also, IIRC the alcohol was added merely to prevent the water from freezing.

Randomly introducing water into the intake for whatever reason is probably not a good idea.

 

well recalling the dozen engines or so I have built, they were all high performance engines,. custom built.....(looks up stock specs of engines)......yeah I was slightly wrong about the 4.0 tolerances, but Honda, and import, and most 2000 and newer domestic, have tolerances as tight as Hondas.

I was right, just not entirely, my bad.

 

Water is used on some aircraft engines. It's introduced as a VAPOR, not a liquid, and then in only small metered amounts. Purpose is to cool by expansion the incoming air to get a denser charge in the cylinders. It's not used to blast out carbon, and certainly isn't done from a cup or garden hose.

The other hype is the WWII P-51 Mustangs used water to temporarily get more power to "get the Hell outa here'. What they never tell you is when the Mustang returned to base with empty water bottles, the engine had to be torn down and rebuilt before it could fly again.

But pouring water down does break up the carbon. The risk is a chunk can get stuck under a valve or on the piston, hitting the roof. It works fine most of the time - so does hitting a 16. Feeling lucky?

 

Never been one on additives myself. After all they are just out there to make money. I figure if the manufacturer had wanted it in there they would have put it in. Personally I prefer good quality oil changed at regular intervals along with good quality gas. Im not knocking the "old school" tricks they just arent for me. With my luck I would choose to stick with poor performance than risk none at all.

 

That's the exact reason I try to use a solvent, so it can burg off, seafoam n mmo are both oil base solvents so after losing up the carbon it burns off that's also why I use it on a hot motor with the plugs out, nice even amount to throughly clean it, I've even seen someone spray easy off in there with a straw, the pulled the head after because I was busting his ***** about it ruining his valves, I ate my words, it friggin cleaned the mother f out if the combustion chamber, 95k later n a few more of his crazy easy offs and his motor runs flawless, its sickening haha