I like Tim's idea of applying heat. If carbon is the cause of the sticking seal then it will take some heat to soften it up and release the seal. As long as you dont go crazy with it it wouldnt hurt to try. An IR thermometer would help insure you dont get it crazy hot.

I worry about those little rubber plugs in the corner seats with the propane torch. Maybe a little gentle heat as a last resort. I'm going to give it another shot this evening.

atf softens it, seafoam dissolves it, heat will just cook it more. ray u wont be heating it enough to effect those plugs if u do go that route. never used MMO so don't know how it reacts with it, but since it is an oil i guess it would soften it too.

ray:

rx7 12a engine

I think that the heat softens it and it hardens when it cools.

At least thats how it acts on my barbque grill. :dunno:

Thanks for the link to that 12A Michael, I think that's Brett's old 85 GS. He recently mentioned it was being parted out. I'll check with him to find out about the engine condition.

So I got into full Hillybilly mode this evening, had a couple beers and took the propane torch to those stuck apex seals.

I did some gentle heating and poking and of course there was a lot of smoke from all that penetrating fluid, but no luck, the stuck seals wouldn't budge. I gave up when the burnt oil smell turned to burnt rubber smell.

So I tore it down.

The good news: The rotors and eshaft look to be in good shape, plus all three flat housings are better than any of those I got from the previous three 12A tear downs. In fact, the flat housings are in such good shape they won't need to be lapped, which will save some shop expenses on my rebuild.

The bad news: Both rotor housings looked good at first, but on closer inspection they turned out to have that minor flaking around the edges, making both unusable. Almost, but no cigar. Most of the rotor side seals were stuck and won't be reusable and the apex seals are too far gone to be useful.

So it looks like I'll be purchasing the full rebuild kit (Atkins, ~$1,000) and I'm still looking for one good 12A rotor housing. There must be one left somewhere.

Sucks they don't make them any more...

Call me stupid but you can re-chrome motorcycle parts.... Can you re-chrome the inside of a housing? or just the whole thing?

side note: All chrome housings that would be a SOLID engine bay! :egrin:

Contact Goopy or Rotary Evolution about resurfacing those housings. Maybe they can save 'em.

I looked into Goopy and Rotary Evolution earlier about some other 12A housings with the same flaking problem around the edges. But from their descriptions of the resurfacing process, it requires that the chrome surface be still fully intact, since their method only polishes out what's already there, it doesn't put anything back.

I keep hearing these urban myths about shops that recoat housings, but as far as I can tell they don't exist and those who have tried failed.

But I'd love to be wrong about that, I now have 11 12A rotor housings sitting on my carport that I can't even send to the aluminum recycler because of the bonded chrome surface.

However it looks like Rotary Evolution does do the all chrome housing thing if you're interested Qingdao:

http://www.rotaryevolution.net/images/21389544_204d.png

ray r u sure that's chromed? they may be just polished.

Or chrome engine paint.

So I started chasing the urban legend about housing coatings and discovered that JHB Performance does do it using a "cermet" coating process, with different levels of quality (A, B and X).

J.H.B. Performance - Cermet-Coated Rotary Engine Components

Not cheap (from $350-$750 per housing, depending on the finish) but certainly less expensive than new.

They also sell 12A housings with reground chrome surfaces for $250 each, again not cheap but at least available (or so they say on the web page).

well at least yo uknow that you can get another housing and do the rebuild. i'm in the same boat as you are... but i need to save some money for the rebuild kit.. time to let more parts go i guess.

hmmm... peaked my interest in the old 12A...

I've not wanted to crack mine open just because I fear what will be inside (or not inside for that matter).

My 12A only has 60k on it and from what I understand thats not a lot of miles for the 12A. Although, it sat for so long two of the front apex seals are stuck. :(


EDIT: thouse housings could be clearcoated polish... Thats what I did to mine on the 13B and they look about the same. But Chrome is maintanance free... and that can't be beat.

12A housings are mysterious things. Mostly, they don't exist.

There may be a couple in that 60,000 unit you've got Qingdao. Then again, there might not be.

One thing I've learned about 12A's over the years is that the sooner you crack them open, the better.

I really should :blush:


Here is a hill billy technique I just used on my latest junk yard find engine...

I put a 19mm socket on the end of my drill... spun the engine fast enough I could stick my finger in the sparkplug hole and tell if it had good compression. That way I didn't need to mount the engine to a transmission to get the starter going. ;)

yes, but be careful spinning the engine with a drill. sometimes the engine will have a tough time getting going and kick the drill out of your hand if you aren't holding it tightly, lol.

I was going to try the drill trick but I didn't have an adapter to fit the socket to the drill. What did you use?

Dave's warning is a good one, best to turn it over by hand first to be sure it's turning freely and then grip the drill tightly with both hand before powering it up.

Also, somebody mentioned earlier about sticking your finger in the exhaust port and feeling for the apex seal while you turn the engine over.

Bad Idea. Good way to take the tip of your finger off!

Does anybody have any information or first hand experience with this cermet coating process for rotor housings? It seems like it might be cost effective, especially if the coating is as good as or better than new.

J.H.B. Performance - Cermet-Coated Rotary Engine Components

I just used my little cordless drill. Those adaptors are a MAJOR time saver; especially since I have a torque setting on my drill.

At these prices, I have several used and new rotor housing I'd sell at close to the same price.

http://i1133.photobucket.com/albums/...housings11.jpg

Cermet X refinishing service $750ea
Cermet A refinishing service $545ea
Cermet B refinishing service $350ea
Chrome grinding service $150ea

Just curious KC, what is the going price for a used 12A rotor housing that would make a good rebuild (ie, is in very good shape, no flaking, no scratches or chatter, chrome not worn thin). It seems like the market on these is very poorly defined.

I have several that are in extremely good condition I'd let go for $350 each. I have two of the older style that are brand new never used that I'd take $1000 for the pair (don't want to split them up).

You are correct about the market on these. There is no common price. I seems like us rotorheads know what we have and what it could cost to replace them. That is why I'm hesitant to sell. I have enough stashed to last a life time but would cost a decent amount if I have to buy them on the open market.

I was lucky on my last rebuild. I had bought a brand new set back in 2004 and paid $350 each. I sat on them until last year. Finding new ones is pretty hard now.

Those sound like very fair prices from what I've seen, especially when compared to the junk you see on ebay sometimes.

I'm going to have a look at one tomorrow that is going for $300, if it's not up to snuff I'll be sending you a pm! That new pair of old housing you have sound fantastic, but will they work with 84/85 rotors and irons, etc?

I think the irons will work but not 100% sure. What I'm not sure of is the intake manifold. The older housings do not have a groove for the water seal. Now if you put in freeze plugs then its not an issue. I've never used them before though. Maybe one of the more seasoned engine builders has more info.

Swap engines with the one in your car Ray. Get it nice and warmed up, then drive the hell out of it. Let centripetal force be your helping hand!

Hey Stu! Where you been hiding? Stop in at Jefferson sometime when you're passing through!