shm21284

Okay, heres my take on steam cleaning. I will not deny that it cleans your engine out, that carbon will be removed, and you engine may run better after you do it. But heres the problem, and it mainly concerns engine longevity and not so much the immediate consequences.
When you go to steam clean an engine, doing it the right way, you pour water slowly down the intake, or spray it with a windex bottle, so that it evaporates as it is enters the lower intake manifold. One problem is that if you do it too fast, you will hydrolock your motor. I'm not suggesting that you will do this if you even remotely know what your doing, but thats a problem if you dont understand the concept.
More importantly, the idea behind cleaning your engine out while the motor is still intact is extremely risky, and heres why. As carbon builds up, it clumps together and crystalizes, getting extremely hard. This is the same carbon that destroys 2nd gen non turbos when someone floors it and sends the built up carbon in the six ports into the motor. Carbon is tough stuff, and can take out apex seals. Now, downsize that carbon. When you steam clean, you merely break that carbon up into tiney little pieces and create a fine grit. Granted, most of the crap is going to be sent out with the exhaust charge. But there is going to be the residue that is left behind, which, acting like sandpaper, will wear away at your housings and apex seals. This will cause fine grooves, premature wear, and ultimately shorten the life of your engine. The little grooves grow to larger ones, which could cause chrome flaking, grooves, wear marks, etc., all resulting in poorer clearences and poorer sealing.
Even worse, though it can not be directly linked, what happens if your engine has TONS of carbon in it? All the engines I've torn down that I didnt own from the get go have had horrible carbon buildup. Say the steam clean breaks off a larger chunk of carbon and it gets wedged between the apex seal and housing, or more likely (since the engine is already in motion) even takes an apex seal out? You've just destroyed a previously running motor.
Water does not dissolve carbon, nor does it react with it to make a different compound, it simply breaks it into SMALLER PIECES. It's comparable to sand and water. Stuff like ATF and decarbonizer dissolve it and/or react with it to make it less harmful.
I dont recommend steam cleaning, nor would I ever contemplate it.
However, I am aware that water injection (where small amounts of water is injected into the engine) is used by racers or even tuners to create a cooling effect in the motor. This doesn't make a serious difference, and should only be used by those who are going to rebuild their engine after the race season or summer fun season anyway. It should be used once youve taken the other means necessary to cool the intake charge and engine (intercooling, better coolant system, etc.)
If you dont like carbon buildup, and dont mind the slight hassle, premix it and ditch that oil metering pump. Mazda made that for the people who aren't hardcore rotary and the people who dont want to take the extra 30 seconds to pour oil into the gas tank after you fill. 2 stroke oil burns cleanely, where motor oil burns and leaves behind ash, building up into that carbon that we hate.
I premix my daily driver. You get into the habit of adding the oil just like you get into the habit of checking your oil and topping it off all the time when running the OMP.

shm21284

I know, its lengthy...

Illswyn

Not lengthy at all. Good to hear all sides on things like that.

Rx7carl

Well written. I hope we can have intelligent talk about this. One thing you mentioned that lit up a light bulb over my head (yea its dim). Aviation piston engines use a different type of oil. It's called AD, which stands for ashless dispersant. It has a very low ash content. Might be worth looking into.

85rotarypower

You know, thats a very good point. Yet another reason to premix too. I'm almost sold on premixing my daily driver. I'm not right now, but I am really thinking of it. That and I don't know how well my OMP works.

IF you think about it, if premixing helps prevent carbon buildup, that would possibly in turn help increase engine life.

BigJim

My understanding with steam cleaning was that it not only breaks up the carbon, but almost liquifies it, so it becomes like a thick jelly. I dont kno how true that is, but i heard it somewhere on here a few times. To me it would make sence, like steaming vegetables, they are very soft afterwards

shm21284

It can't liquify it, its not a solvant. It just breaks it into smaller peices. That Ashless Dispersant sounds like a good way to go if you dont want to premix; however, we will need to see what weights are offered.
Sidenote: vegetables are porous and have living cells, when you saturate them with water, they get soft, like your skin, wood, etc. When you saturate gravel, dirt, or something like that with water, it is just a bunch of water and sand, or water and carbon. The thing is, the carbon is suspended in the water at a level not visible to the naked eye, so it APPEARS to be not as harmful as it actually is.

GavinJuice

^

GtoRx7

iTrader: (5)

Great post Seth!! Haha me and him have been tearing down motors and rebuilding them on a consistant basis now, and the carbon buildup is pretty shocking. And is the top killer for the FC non-turbo cars. Thanks to my dad teaching us the art of rebuilds, its let us warn others about carbon. Not to mention both my 7's have new motors that I can take care of myself from start to finish. Now shm21284 can enjoy is own new motor too, without carbon!!!

RotaryRyan

theres a thread on how to clean the carb and engine internals with amsoil powerfoam. what do you guys think about that stuff?

d0 Luck

ATF expands the rubber seals

not cool at all

Jeff20B

iTrader: (13)

MMO should be less harmful to rubber (and other soft) seals.

Junia

Does frequently running the motor hard help against carbon buidup. I wouldn't mind premixing with 2 cycle oil but I don't know how to kill the OMP and it doesn't leak or anything so I never had a reason to take it apart. I make sure I run the car up to about 7500-8000 on full throttle atleast once or twice whenever I drive it. Of course only after its warm.

RotaryRyan

but what about powerfoam?

Jeff20B

iTrader: (13)

Powerfoam is supposed to be good. Just don't use oven cleaner. Ask peejay.

Junia, they say a redline a day keeps carbon away. My 20B was filled with carbon due to the wrong plugs (cooler heat range than stock) and the sedentary driving style of a luxury car.

REVHED

That's not how I drive my Cosmo.

riofrio

Can you have substantial carbon built up, and not know it?? I mean, wouldn't you be able to notice lack of power or something?
I'm probably gonna do the Amsoil Power Foam thing soon anyway.... just need to find the stuff.

Jeff20B

iTrader: (13)

Hehe!

My 20B had FC plugs (7 and 9) instead of the higher heat range plugs it was supposed to have (6 and 8). The apex seals were glued to the rotors from a lot of carbon buildup. I soaked them in MMO and it loosened the carbon and flushed it out. Now they spring back out when push inward with a popsicle stick.

I once did the water down the carb trick on my '69 Corona over 10 years ago, but I've never done it on a rotary. I guess I've never had a carbon problem.

Aaron Cake

iTrader: (1)

Care to explain to me how you can hydrolock a rotary?

Huh? Since when? 2nd gen NAs just tend to wear out. The apex seals get too thin, then roll out of the rotors. Carbon is a VERY RARE cause of death, and normally manifests itself in the form of "carbon lock", which again, is very rare.

That would be carbon lock.

LOL. And at the same time turn your oil o-rings and coolant o-rings (if it happens to reach them) into mush.

Yeah, right. :rolleys: I've torn apart engines that have been premixed all they're life, and have still had 2MM of carbon caked onto the rotors.

GtoRx7

iTrader: (5)

Explain to us all how you Can Not hydrolock a motor that has compression? I dont see how a rotary cannot hydrolock, if it compresses a great amount of water, water will not compress. Correct me if I am wrong about that.
Since when? Well this may vary from state to state, and maybe from around the world, but for me, in Ohio, 99% of the second gen rx-7's with a bad motor is from carbon falling into a running motor when the 5th 6th ports open. I dont want to start a debate, just I have NEVER seen a 2nd gen motor wear out and pop a seal. My dad owns a Mazda shop for 30 years, and in the past 4-6 years have rebuilt about (just a estimate) 30 second gen motors with less than 150k miles on them, blown from carbon destroying a rotor and housing. Always just one rotor, the other rotor and housing are always in great shape, apex seal WELL within spec and not even close to being worn out. I may post pics of a motor with 150k on it, and how nice all the parts were in (except the side that blew of course). So unless the are you live in a area everybody drives a 7 like they should and do not get the carbon in the ports built up, then maybe all the motors you see are worn out. On that note, I personally just sold a 87 rx-7 that had 265,00 miles on it, no carbon in the intake, both operated correctly, because the driver took care of it, ran it hard, changed the oil ect. Mazda builds great motors, the 12a can easily last 200k, the GSL-SE easily will last 250k and a second gen can surpass 300k with the right drives and maintance. All of the numbers I have seen or own to prove.

THis may sound bad, but some of the recent motors we rebuilt have had 5+ mm of carbon buildup, haaha sooo much that it was machined looking from contacting the rotor housing when going around. That is crazy stuff there. And also note pre-mix is only one thing to prevent carbon buildup ,as I am sure you know.Spark plug changing, fuel quality, fuel filters, air filters, and driving style conditions can still buildup carbon from just improper fuel burning. Oil ash is only one piece of the puzzle.

To wrap it up, I believe that all of the Rx-7's are old, and most have been abused, and have taken it well. The only REAL all-out solution to carbon is buy a new rebuilt motor, or rebuild it yourself, and start from scratch. You can take care of it forever, warm it up everyday, change oil every 3k, put in new plugs every 15k, change the fuel filter every 20-30k, and inspect the air filter, and it will run STRONGER and Longer than 98% of the used motors out there. A new motor is expensive, but compared to how much we all pour into making a rotary faster, $1,500-2,300 put into a new Wankle, will beat every aftermarket exhaust and intake you can buy! And its a joy to break it in yourself, and take care of it. If your real good ,rebuild it yourself for $500-1000 in parts. SHM21284 spent $680 in parts to rebuild his 12a, and after we get it done ,it will 10x better than the crusty 5mm carbon **** brick it once was, that no steam clean, atf, foamy stuff will ever clean it as well.

Well, now that is a long post, and I'm sure I'll get some nice replys to it. But remember, 1st gens are cheap to buy, so a new motor is not to expensive.

GtoRx7

iTrader: (5)

I must add that most of the time all the carbon is from the rotary burning oil, from weak oil seals letting oil get into the combustion chamber on decel and accel. So cleaning the carbon in this case is like trying to fix a chainsaw gash with a bandaid. Sometimes you have to ask yourself, is this motor worth trying to save? And if I do save it, how much damage will result? How cheap am i trying to be? I must add that SHM21284's motor was previously owned by me, and the previous owner had over heated it many times! It still ran good, It got over-reved quite a few times from Me and SHM21284, it was detonated a few times too. Still ran very nice. And the topper....it was not a factory motor, it was a half-*** rebuild, that was missing all but 2 of the rubber assist peices on the corner seals. They are suppose to have 12! Rubber assist peices help prevent blow-by and help with sealing. Combine that with being overheated, the o-ring seals were weakened and the springs became soft, letting oil into the combustion chamber on decel. All this was on a motor that ran good!! So how much do you really know the history on your motor? DId you own it from day one? How do you know what its been through? You dont.........

d0 Luck

what's the big deal w/ this hydrolocking deal? i've hydrolocked my 13b many times and all i would do is just get back in and start it up... no problems at all

if it hydrolocks, so be it... it's not like it's the end of the motor's life

and it's not like 1 gallon of water is stuck in there

shm21284

are you sure your hydro locking? Because it wont start if it does, water does not compress.
and this thread is not about hydrolocking, if you want to talk about it, start a new one. I just mentioned that as a reason pouring water into your motor is dangerous.

shm21284

I know. I was explaining that for people that did not know what carbon lock was.
As for cleaning your the carbon off your engine without actually tearing it down, those powerfoam methods, using ATF, which i did not know would hurt the rubber side seals, and other methods, are only for those people who have 5 dollars and cant afford to buy/build an engine. In the grand scheme of things, those methods should only as a last resort and quick fix. I would NEVER pour anything down my engine except a proper air/fuel ratio. I do not see the benefit in doing a quick fix because it always ends up costing you in the future; i have found this out the hard way. Why be cheap and have to fix it again in a week, day, or the near future, when you could spend an extra couple bucks, do it right, and KNOW that you will maintain a perfect motor right? It ends up costing much less, being less of a hassle, and much more reliable in the long run.
Anyone knows that burning gasoline creates carbon, so carbon buildup is inevitable, and an engine will not last forever. But doing the quick fix (steam clean, ATF, powerfoam, etc) dont really solve the problem, they either put the problem off, or create new ones altogether. There comes a time when you have to just suck it up and do it right.
Basically, I'm saying that if you think you have to steam clean your engine in order to make it run properly or get performance out of it, its probably time to just buy a new one. And if your doing it as a periodical maintenence method, i wrote this article to stear you away from that due to the hazards it creates. IF YOU DONT KNOW WHAT YOUR DOING, you could hydrolock the engine. and yes, you can hydrolock a rotary. If it is a four or two cycle engine, especially one that uses COMPRESSION by oscillation (not compression like a jet engine or turbo), you can hydrolock it. Water fills up the combustion chamber, and when the piston or rotor goes to compress it, it cant, so it stops. Another hazard it creates, if you missed it in my original post, is unecessary wear because of the carbon's sandpaper effect as it is broken up into tiney pieces and creates wear into the housings and seals.

shm21284

No, it's not like it's the end of the motors life. But what a pain in the *** it is to get the water out. You just created a hassle you didn't have to deal with before.
And it could cause unecessary damage.
Or if you dont know when to stop, you could force it so hard that it causes the apex seal to to lose it's sealing effect. So maybe it is the end of the engine's life. Unless you like driving an engine with power on 1 rotor and half the other rotor?