heres a picture of a rotor with 175,000miles on it. no decarboning

 

that's about what mine looked like at 100k, I'll look for a pic.

 

sweet the carbon must have reised your compression lol.
no thats realy nasty looking one of those gobs was just waiting to break off and screw an apex seal. what was the history of that motor in terms of maintenece and usage?

 

theres not enough carbon there to break off. its a really thin layer, one thats normal if theres fire. engine looks like it was maintained and driven normally

 

Sorry to say something negative, but last time I checked water dosent compress very well. I will never pour water down my engine, this "trick" sounds very risky as a couple others have said. And in my experience, most rotary's that are non-turbo die from carbon build up in the intake 5th and 6th ports, falling into the motor when someone after driving slow for years opens in up. Ususally the carbon on the rotors flakes off, in little pieces, that will scar the housing. But to wipe out a apex seal it takes a nice lump of carbon, which is in the intake ports. Usually. But whatever, everyone has there own opinions, haha

 

not a very good picture, but heres mine at just over 100k



Engine was perfect, save a blown coolant seal

 

where does this magic intake carbon come from?

 

Exhaust comming back into the intake stroke I imagine...

And yes it does happen, i'm currently cleaning the crap off the inside of one of my irons i'm porting.

 

I am not a absoulte expert on the subject, but I dont think all of the carbon builds up from the exhaust charge going into the intake. Because on the 5th and 6th ports, they can be completely closed, yet buildup can fill the entire port with carbon and dirt. The current engine I'm rebuilding suffered from this, as it only happens in engines driven below 4k for many years. As much city drivers shift at below the opening rpm of the ports, let alone get the 3rd and 4th ports flowing. When I got this motor to rebuild the front rotor was completley trashed and so was the housing. And both 5th and 6th ports were partially open, and stuck. From a switch in owners, the motor ingested a **** load of rock hard crap. Most people dont change the air filter reguarly, and dirt enters the motor. And most of all I think it can build up from every start up when the engine "reburns" the vapors of the charcoal canistor, which has fuel and oil residue from the crankcase. Which over 4-10 years this small buildup from never opening the ports gets really BAD! If only everyone ran the car hard from time to time to suck in the very minute amount of dirt, and the buildup wont happen. Of course you cant find many second gen cars that have been driven properly, so you can try to clean them, or just rebuild it and start with a clean slate!
Oh yeah the carbon buildup doesnt seem to affect the turbo's, as people run them harder in general, and the ports are constanly getting flushed out, even if you drive it easy. And damn I did a long post....

 

I personally think it has alot more to do with exhuast comming back into the inlet... The dynamic supercharging inlet manifold alows exhaust 'pulses', which will contain some ammount of carbon, to enter the inlet manifold..
The 5th and 6th ports are connected in the inlet manifold, and if they don't open up the carbon just builds up in the sleeve bit.

Thats my take on it...

 

Well I just pulled the OMP vac line on the back of the UIM I prolly put a gallon of water through my engine, I did not do it all at one time, just feed enough water for it to bog down then I would bloack the water line and rev the engine slightly until it would regain a normal idle. I kept feeding it water untill all the black/grey smoke stoped coming out the tail pipe, then i let it ide for 10-15, my car felt much better afterwards.

the water turns to steam as soon as it hits the lower manifold, and since it is mixed with fuel as well as air, it can be compressed without ill effects, in this case it just raises the resistance to combustion, as well as vaporizing the carbon from the inside of the motor

 

Most comes from the PCV (positive crank ventilation) system. Oil from your filler neck, Oil slosh. ect.

 

Please explain why this works? Do you have a motive? And concrete examples that this actually worked/improved anything?

 

exactly!

 

I did the exact same procedure not too long ago.. I too thought my engine ran better afterwards. I had an eratic idle that just went away after I did the water trick. Not quite sure what it was.. maybe the plugs were restored by the procedure. I did change the plugs afterwards anyway just in case. I must say I have never taken off such clean plugs from my FC before. I have no way to prove that my car ran better.. I just know it did.. it felt smoother and quieter, even my exhaust tamed down a bit. I will do this again with every tune-up now from now on.

 

some of you guys are idiots. sorry to sound like a jerk, but its true.

there is magical carbon in the intake. it comes from the EGR system. the reason the carbon sticks so well inside the intake tract is due to the oil vapors from the PCV system that re-enters the intake tract via the air inlet pipe.

there is no oil residue from the Charcoal vapor system. the only lines that go to that charcoal vapor canister is a vent line from the tank (no oil in there) and a purge line that goes, indirectly, back into the intake system (no oil sources in there)

there is no exhaust reversion, per se, where exhaust gas is left over from the previous cycle and flows back into the intake ports before the fresh air comes back in. there may be stagnant residual exhaust that can dilute the new intake charge on the upcoming cycle... but not a shitload of exhaust that purges back into the intake.

pouring water down an internal combustion engine is a widely known and long held technique thats been around FOREVER... well before the rotary was a gleam in the Mazda's collective eye. what happens is that water (not gallons and gallons ) is ingested into the cylinder along w/ the air fuel mix. when the air fuel mix combusts, the cylinder temps sky rocket and completely vaporizes and water droplets. this creates SUPER-Mega-Heated steam. and the turbulence inside the cylinders from the tumble effect of the intake charge and flame from propegation swirl the steam inside the cylinder and "scrubs" and Steam cleans the engine from the inside out. you know all those super heated steam cleaners they sell at Wal-mart and on TV and how Great they clean and disinfect surfaces? well thats the same principle here. Water is the universal solvent. its strong enough to dissolve and erode ROCKs... why wouldnt it work on carbon? given enough time, water can break anything down... but some things would take centuries, even Eons.

a rotary CAN hydrolock if you give it too much water. water is, of course, incompressible. if too much water is released into the intake and takes up too much volume inside the rotor housing, the motor will not be able to compress the volume of air that is LEFT enough to where the rotor can complete its cycle. of course, if its Completely filled w/ water or any liquid in a sealed chamber, the volume cannot be decreased since the molecules are as closed together as they can possible get w/o turning it into a solid mass.

ever see a piston motor w/ a blown headgasket? coolant leaks into the cylinder during the intake stroke and turns into super heated steam during the combustion stroke. if you ever take the head of, or even the plug, youll see the parts in that cylinder are as clean as they were the day they were installed.

the one good thing i see is Philips rotor housings look good, i dont see and chrome flaking off

using a small diameter vaccum hose will not allow the motor to suck in enough water to damage itself. trust me. infact, this is the EXACT same method recommended by the Mopar motor company. they sell a product in the Parts department called Mopar Combustion Chamber Cleaner. its very popular in my DSM crowd. its like an aerasol can but i dont thikn its pressurized. so its like 14 oz of liquid. you tap it into a vaccum line from a manifold source, and it sucks in the liquid at its OWN PACE; hence cannot suck in too much liquid. If the motor could do so and potentially damage itself, the Mopar dealerships would not sell, utilize and recommend such an item or procedure.

thanks for listening

 

flubyux2: Woo, thanks

 

so doesn anyone know the exact vac hose that should be used?