I personally love driving on one rotor, its the only time I can say my car is a single rotor......ahhh, no nevermind, that sucked pretty bad. Haha

 

If i were to judge people by their signatures, i dont know what ide say for you. probably think you were the new mazda rx7 f1 edition

 

man thats a long sig.

 

shm21284 - Have you actually seen the damage inside of a rotary engine after it's been steam cleaned?

It would seem to me that this carbon sandpaper effect that you speak of would at worst only last a couple rotations of the rotor. Sure that's enough for it to possibly cause some damage but it WILL get blasted out the exhaust manifold.

Thanks for your writeup but it hasn't convinced me that this is a bad thing yet.

 

no, i have not. I have never steam cleaned an engine and have no idea if the motors ive torn down have been. The idea of this was to bring up possible problems.

 

i've had better results with Amsoil Power Foam than with steam. but mabye that's just me.

 

Almost all the 12a motors I've torn down have had bad housing wear, mostly on the bottom right after the exhaust cycle. I think possibly alot of 12a that are original are suffering from bad omp's. Also there are MANY rebuild shops that will re-use these horrible housings to save money. The difference between a good or new housing and a worn one with missing chrome (well it hasnt been chrome since 74, but I still call it that) is HUGE. That why most motors with carbon build-up so bad have shot housings too, possibly from the carbon wearing away at it. That's why I think its kinda Hill-billy to try and clean a motor that is most likely shot anyway. Dont want to sound negative, but as I said before, these are old *** motors, that paid their dues. If its running just take care of it until its dead. I've owned 10 rx-7s, and only my two current ones have new motors, and all of them ran, and drove good if driven periodically. The others had high mileage and ran good, some bad. If the carbon is that bad, the motor is most likely too. Right? Dont kick a dead dog!

 

Welllllp,

I can offer this experience from bladesmithing;

After a carbon build-up on a piece of steel (carbon is carbon- duddin matter where it came from), when it's hot and you plunge it into oil or water, it crackles and comes off in flakes very quickly.

My take on that is that it's simply a reaction of two materials with different coefficients of expansion. Though the metal and the carbon may actually have similar expansion coefficients, the carbon is getting shrunk very suddenly by the cool water and the larger piece of steel is taking much longer to shrink (or in the case of the engine, is negligably cooling).

But the carbon that comes off does so in flakes.

I've said it before here- carbon is hard ****! It's certainly harder than the chromium plating on the inside of the housing, and very little isn't harder than hot cast iron seals!

Based on that perspective, I would say that soaking the engine in solvent would be a better way to initially remove the carbon, and then perhaps follow up with an occassional water-torture.

Now since Jon's great write-up thread is closed, I'll entertain this here;
Could somebody maybe sit outside on a Saturday afternenoon, cook some ribs, have some beer, and boil some old engine rubbers in pots of ATF and MMO for a few hours to see what that stuff really does to the engine seals?

I would do it if there were rubber seals like that in carbs...you know, but uhh, well, it's just not my area. ...pass the buck-pass the buck!

 

great post shm, but it's still a good incentive that i always think about (steam cleaning)

so far, no problems w/ my motor... then again, i've only clocked 15k on my new rebuild

 

I have fixed a 3rd gen that drove into a flood without disassembling the engine. Had to drain the intecooler, turbo, intake manifold, exhaust, intercooler, engine, etc. of all the water that it sucked up. There was a couple of gallons! Changed the plugs, and all the fluids. We pulled the car down the street in gear to get it all dried out inside. Did the compression check and it appeared to be back to normal. Put everything back together and pulled it back down the street in gear. After about a half a mile it started. It took a couple of days but it eventually got full power back and ran like a champ. I'm more worried about the crap in the water than the water itself.

It is quite easy to explain why the apex seals didn't die. Look at your apex seals sometime. The top of them is rounded due to their movement within the motor. This allows some water to get under them. When the rotor closes down and compresses, obviously the water can't compress, but it can be pressurized. The small amount of water under the edge of the seals pushes them back into their grooves and allows the water to drain on to the next chamber and so forth and so on. A piston engine doesn't have rounded edges on their piston rings. Water can't get around them without breaking them. This keeps alot of pressure in the cylinder and the weakest link is going to break. Even if the piston rings did allow water to get by, it would still go into the crankcase and cause a very bad day.

The number one rebuttal I get to this is the fact that there is always fuel or water in the case of water injection in the engine and that it should theoretically do the same thing by pushing on the seals. You need to remember that there is also air in the engine. It can compress and this takes the pressure off of the small amount of fuel in the engine. It won't push up (or down depending on your point of view) on the seals.

I'm not saying that you can't break any seals from water ingestion. It is just unlikely compared to any other engine. I don't buy the hydrolock statement. It will flood. It won't hydrolock.

There have been race engines with carbon apex seals that broke their seals yet had no damage to the rotor housings. Others have destroyed them. Something to think about.

 

If you think about it, the water is going to push back against the apex seals. Yes, they have rounded edges, but its going to be pushing against the seals perpendicular to the way their bore in the rotor. This will cause it to kink or bind against the rotor itself, causing it not to move. Its much easier for the apex seal to kink and not move than it is for the apex seal to allow the water to move up over the rounded edge and push the apex seal down (which has no slop in its bore, so it will bind against the rotor on its way down anyway, creating more reason for it not to move down) than it is for the apex seal to just be pushed back a little bit and for it to kink in its spot and not move anywhere at all. steel against steel friction is amazing, trains use steel trucks on steel tracks and get little to no slip. Rotaries can be hydrolocked, period. They might be not as easy to hydrolock, but its idiotic to think that its not possible to hydrolock.
By the way, im not going to argue about hydrolocking in this thread. Start a new one about it if you want to discuss it. I was purely using hydrolocking as an example for not pouring water down your engine because its possible if you dont know what the **** your doing and you think pouring water down it is going to help. You could easily screw things up.
Yes, maybe it was a bit of an extreme example, ill admit that. But its not at all impossible, and that's why i used it. I think that people see that as my first example and automatically assume that's the crux of my argument. The strongest argument i have against steam cleaning is the fact that carbon gets broken up, wedged into the nooks and crannies, and causes excessive wear. Yes, the bulk probably gets blown out when it gets broken off the rotor faces, but its the little stuff that hurts. We can see the big **** coming out of the engine, its blackish smoke. The small **** gets wedged in apex seal slots, behind the side seals, between the apex seals and the housings, between the side seals and housings, behind the corner seals, between the corner seals and housings, etc. Carbon is hard ****, and will easily cause the exessive wear that is not needed.
Yes, i know that carbon gets in all those places anyway. Its more reason for it to be displaced there, though. It's more reason for carbon to get stuck in places the seals do their sealing, and in my mind, it's just plane stupid to do a half assed cleaning job when your motor is together when, if it really needs it, you could take the engine apart, rebuild it, and save the housings that could be good rather than try and get a little more life out of the engine and tear the housings up, spending more money on new housings that may have not been necessary in the first place (of course if your doing a racing engine, or an engine you want to be a 100% new, you buy new housings anyway). THIS IS MY OPINION ON STEAM CLEANING!!!!!! your not going to change it. thanks for reading my post, if you agree with me, great; if you dont, that's fine too, your entitle to your own opinion. I just think it's crazy to do this. it's halfassed, that's all.

 

I wont respond to anything that doesn't have to deal with steam cleaning directly. start a new post for anything else.

 

If steam cleaning with water could cause the carbon deposits to flake and possibly scour the housings, would 'mixing' the water with MMO or the like help?
I guess restated- Would the addition of a non-fryable lubricant help to provide a coating to absorb the carbon and reduce the chance of scouring?

 

it could, but as we know from chemistry, water and oil does not mix. it would be hard to get it to do what you want it to (create a compound that acts like a steam cleaner as well as an oil to dissolve the carbon)

 

I was thinking of that, but if you shake it in a bottle or container periodically before applying it there should be enough 'mixed' in suspension until it seperates (like oil and vinegar salad dressing).

 

You just did previous to this post. It was never stated that it was impossible to do, just highly unlikely. I'm not going to deal with this post anymore for fear someone might actually learn something. Back to your steam cleaning bit...

 

Ok, we got some good ideas.
It's all for the common good, right?
Instead of getting upset and making each other feel like we're pissing on each other's theories, is there any way we can prove some stuff?

 

yeah i agree, its not like this has been proven. its hard to not get mad when someone wants to "roll their eyes" and make you feel like an idiot. plus, it doesnt help when i responded drunk last night i should remove those replies

 

Im only 19 anyway. so its not like i know everything... im open for criticism but not for attacks.

 

Getting drunk already? You should read the rotary displacement threads, AHaha, just kidding. Next time I'm about to rebuild a running old motor, I think I will steam clean it first, and using my borescope look at the before and after, then tear down the motor and see if any signs of damage, or help it provided. That is the only way we can find out. The problem is waiting for that motor to come along. Hmmm, hey SHM21284 we could use Peter's motor, It has 200k on it, and whenever he saves up for a rebuild we will do it to his...... yeah

 

a lot of good **** in here , im not going to add to the propaganda. Good info , a worthwhile thread
...cheers

 

Steam clean one rotor housing, break down the motor, and see if there is any difference between front/rear housing.

 

Forgot about this thread...

A rotary won't hydrolock because it has very low static compression...Lets say you completely fill the combustion area with water...Simply rotate the engine slowly by hand. Or remove the plugs.

As for the carbon, well, I don't know if I can believe that carbon related injuries are because the 5th/6th ports are disloging stuck carbon...This thread is the first time I have ever heard of that, and while I have not been involved in rotary cars for 30 years (I'm only 24), I have to believe that I would have at least heard of this phenomenon before this thread.

BTW, sorry if I sounded hostile in my first reply...Too used to the 2nd gen forum I guess.

 

what about the motorvac stuff.....i've taken valves off piston engines just after they been motorvac'd and they looked reall clean to me compared to a non motorvac'd motor...it's much better than the cheap stuff u pour into ur gas tank....and i think for people too forgetful/lazy to premix u can hook up a reservoir to the OMP and put any kind of oil in it....wire up one of those low washer fluid detector things to a buzzer or a light on ur dash to let u know when u need to fill it up....a guy from belgium had a write up on it here....he used a beer keg as a reservoir...lol

 

It is strange that you havent heard of it. I'm thinking maybe it is happing alot, but is getting blamed as something else. Example, a guy buys a used rx-7 runs it hard and it wipes out a apex seal, tears it down and sees a exploded apex seal assumes it was due to it being fragile or worn out, and so it is never documented. I wish I had more photos, I've only been on here for about 1-2 years, and didnt always have digi cam. I swear the next second gen motor I get that is all clogged up I will take gobs of pics. Hmmm I did save the rotor and housing from my second gen motor, could show pics of that, but I never photo'd the carbon in the ports . Oh well, soon I will have pics for you guys........