Dissolving carbon?

It's the old rotary bugaboo rearing its ugly head: carbon making the side seals stick. In the olden daze ATF was the snake oil of choice but it appears it attacks the rubber seals that are used on the 'scrapers' (rotards will know what I'm on about). Seafoam seems to have a similar effect. WD40 does a decent job, the idea is to keep the inside of the motor wet with the stuff for a week or two, blow it out of the spark plug holes, then run water through it (sucked in through vacuum ports with the engine running) and last is the fun part: an Italian tuneup. Good ol' motor oil will work too, same setup.

So here's the question: are there any other good carbon dissolvers out there?

Steam works great on piston engines(water misted into the intake or sucked through a vacuum line, run it hard after to cook any water out of the oil), IDK about a Dorito motor though.

I highly doubt ATF is going to attack anything designed to live inside an engine, especially compared to WD-40.

I thought this was a thread conspiring against me.

Old school rotor or new school?

I always liked Marvel Mystery Oil or, very rarely, a real strong Seafoam dose, like a small bottle in 1/8 tank, but beware, it will smoke out the neighborhood.

Marvel Mystery oil is my carbon disolver of choice. I use it in the gas of small engines that burn oil and carbon up. It keeps them clean inside. You also can use it to replace up to 1/5 the engine oil. I have not used it in a modern engine besides a piston soak for a Saturn. I don't know if it is safe for apex seals.

I don't know of any real carbon solvent that won't destroy,rubber. I honestly think you're out of luck on that front.

But, the effectiveness of water at breaking off carbon deposits is quite real. I would attempt this.

I use gun cleaning solvent for carbon stuff, its what its made for. Most stuff will be ok on plastics and rubber but definitly check the label first.

hmmmm, that snake oil Shelby use to hawk.... I seem to remember carbon disolving in the marketing.

In reply to oldeskewltoy:

I think it was Z-Max

Which according to the msds, is almost pure mineral oil. Not a noted carbon solvent.

In all sincerity, black rubber gets it coloring from carbon black. Which will dissolve out if you use a good carbon solvent. There are many detergents and such marketed as magical carbon solvents, but they really aren't. Real carbon solvents will eat out the carbon content of any black rubber.

caviat emptor

I can't imagine that any "rubber" that is durable enough to live under the heat of a rotary would be the typical black rubber variety.

Here is a kit for a RX7. It looks like the apex seals are white rubber. Google, Duck Duck Go or Bing "MMO clean apex seals" and you will see lots of stories about cleaning apex seals. I don't know if any of them are true.

Mopar dealerships sell a product called "combustion chamber cleaner." Supposed to spray it into a running engine...the bottle doesn't say anything about how it affects rubber seals though. Here were the results on my really ghetto BP engine refresh.

Water makes a fantastic combustion chamber cleaner as well. Results will be just as pretty.

Won't usually free up stuck rings though. Or rotary seals.

^^^ Just be careful and don't use too much.

BTW, doesn't Ford use some kind of carbon cleaner prior to changing spark plugs in the 5.4 Triton engine?

Another option is to run premix with a higher end synthetic two-smoke oil. Those have additives that are intended to clean up carbon deposits as that's also a problem with two strokes that aren't driven/ridden like rental cars.

In reply to pjbgravely:

I seriously doubt that the apex seals are made from anything rubbery. Steel or ceramic, yes.

Apex seals are definitely not rubber. Water seals, maybe, but I doubt it's run of the mill stuff due to the heat.

Order some Idemitsu rotary premix, it has junk in it to prevent and perhaps clean up carbon. You can get it from Mazdatrix for reasonable money.

Whatever ATF my dad had laying around and a 2 week trip to Mexico was all it took to get my 89 RX-7 running.

Pulled the plugs, poured ATF down the lower ones, bumped the motor, repeated a few times, left for Mexico for 2 weeks, came back, put a booster on the battery, went inside, pooped in my own toilet, came back outside, put the plugs in, and she fired right up. Car ran great for 9 months, sold it running great.