?Hillybilly method for compression testing?
 

Two related questions, if anybody might have some experience or suggestions:

1) Is there a low tech alternative for compression testing (if you don't have access to the factory tester) that is more quantitative than the "swoosh" test?

2) Any tricks for coaxing a sticky apex seal back into action, without tearing the engine down?

I recently acquired a 12A of uncertain provenance (thanks go to Alex!) looks pretty decent and swooshes pretty well. It has two nicely floating apex seals on each rotor, but the third seal is stuck on each rotor. I'm soaking the rotor chambers in sea foam, trying to coax the stuck apex seals loose with a bit of finger pressure through the exhaust ports, but so far no luck. I know a 12A will actually run pretty well if some of the seals are stuck, but it would be nice to have them all working (of course there's no way to know how the side seals are doing).

I need to decide whether to tear this engine down, hoping for a decent rotor housing I need for a complete rebuild, or instead, using it as is and hope for some quality miles while I take my with the current rebuild and keep searching for a decent 12A rotor housing.

Obviously, some reasonably accurate compression data would be really nice to have.

Any suggestions are much appreciated.

Thanks!

Get a cheap piston compression tester from Harbor Freight and just hold the relief valve open while it cranks, that will let you know if the 3 sides are even (or how far off they are) Then you can close the valve and see how high it builds up, that gives you an idea of how good the "best" side of the rotor is...
Not extremely accurate of course, but gives you a good idea if the thing is any good at least... I've done it many a time!

I think that's the "swoosh" test he's talking about in #1. I don't know of any other way to get a more quantitative than that.

Ray, I say you tear it down. At this point you risk doing more harm than good by trying to coax it into working. Tear it down and hope that it gives you what you need for a good rebuild.

I agree a teardown is probably in order. I assumed he was referring to the test where you literally spin it over and listen for strong whoosh sounds.

Yep, we're all Hillybilly's down here. I was referring to the Original Swoosh Test (OST), whereby you turn it over with a socket wrench and listen for the "swoosh" as the seafoam gets swooshed out #1.

If you crank it really hard, you can see a seafoam mist blowing out. Encouraging, but not very quantitative.

I'll get one of those boinger testers you suggest Sean. Crit used to have one like that he lent me a couple years ago. It was pretty jumpy, but if you got it just right you could compare compression on all three faces, which is what I need. Thanks for the tip.

As far as the tear down goes, yeah, you guys are right of course. But it's a $1000 plus decision, so I thought I'd give it some thought.

And another day or two to give those stuck apex seals a chance to get unstuck.

i've had apex seals soaking in mmo and seafoam and pb blaster for like 2 years..and they still refuse to budge..

You're so helpful Dave. Have you ever heard of the Rotary Gods? I pray to them every evening.

You never know, these two seals could be the ones that decide they want to get back in action.

I'll give them two more days, then it's tear down time.

what i've done to an engine once was to put a long bolt in the flywheel(think hand crank). if u got a spare tranny, starter and battery, just bolt them together. u get the idea?

I've had my 12A soaking in ATF and turned once a week for about 6 months... No compression on two faces still.. :(

That long bolt idea is pretty clever Michael, I'll have to give that a try. I do have a spare transmission and starter handy, if I need that.

I'll check out autozone for one of those boinger compression gauges today.

Dave, Qingdao, you guys are right of course, there's no chance in hell those stuck seals will come loose. But you never know, this could be the first time.

used atf on the current one. turning by hand had good compression on the front but absolutely none on the rear. didn't have a bat at the time so couldn't spin it fast enough so i put atf in it and let it sit til the next weekend just in case.

Hell its worth a shot at least lol. I too though have had mmo and pb blaster etc soaking in one 12a on and off for months now and no luck. Granted I haven't touched that engine in weeks so who knows, maybe it worked haha

You might try bringing the stuck seals around to the exhaust ports and gently tapping on them
while applying penatraing oil and some heat from a plumbers torch. That may loosen them
enough without damaging them.

You know hooking the starter up and cranking it might just loosen things up as well. I think
Michael might be onto something there.

they may come free... but i worry about the apex seal spring under the seal becoming flattened from being crunched down so long and needing replacing..

my fingers are crossed though.. i haven't touched that SE engine in months and i'm hoping for the best. if not, i've got some guns for sale.. i'll just either rebuild what i have or look for a good SE short block.

I'd be worried that cranking the engine with a stuck seal might do damage to the rotor housings. Good housings are so hard to get nowadays that I wouldn't even risk it.

If you don't want to make it a $1000 decision, you don't necessarily have to build it with brand new seals and everything. It's better to do that but you could tear the engine down and see if the apex seals are still within spec and skip buying them, getting just a soft seal kit.

Jon

The Hillybilly in me wants to do it Tim's way - A couple of beers, some penetrating fluid, a propane torch and a prayer.

But the Conservative in me says Jon is right - Tear that thing down now, before I mess something up, and hope for a decent housing. Then go from there.

So unless the Rotary Gods have visited my 12A since last night and miraculously freed those stuck seals from their bondage, it looks like I'll be moving on to Plan B.

Thanks for the insights folks!

Ray == conservative - doesn't compute!

You can tear it down or not, either way you will have to unstick those apex seals.

Here's an inexpensive tester

Harbor Fright
ATHENS, GA #331 (14.4 mi)
1850 EPPS BRIDGE PKWY 315
ATHENS,GA 30606

Compression Test Kit

Looks like just the tool I need KC, and it's right down the street from me, thanks for the link. If I can just nurse those apex seals a little bit more, I might get them to come back to life, then I'll need that tester to go on to the next step.

Progress on the apex seals is still uncertain, I haven't torn it down yet because I want to give the Rotary Gods every possible opportunity to help me out on this.

So I'm using a modification of Tim's Hillbilly Apex Seal Laxative (HASL) approach: A couple beers, lots of PB blaster, several prayers and gentle persuasion with a screw driver. (I'm leaving the propane torch and hammer in the shed for now).

Kind of like a sensitive hillybilly approach, it's popular among us Wankel Whisperers.

I'll get back with the results tomorrow evening.

Way to go Ray, next I'll have you seating rear wheel bearings using an iron pipe.

if i was a hillbilly id stick my finger in it and spin it over you should be able to feel all the seals as they rotate. just my .02 :egrin:

just out of curiosity but if the apex seal is pushed in to where its not making compression, but spins freely, then wouldn't it be able to go by the housings without messing anything up? i could see if they were stuck out to where it would turn halfway and stop how that would scar a housing, but then again i've never tore an engine down so i maybe missing something.

^exactly how i see it.

i agree. i have been spinning my 13B for years on random occasions without damaging the housings! i don't even think the apex seals are making much contact with the housing at all.

Yes that seems to be the case with the 12A I'm looking at, the apex seals look fine and I don't think there is any contact with the rotor housings because the springs can't push them out anymore. And I'm assuming this is going to be bad for compression on that face of the rotor.

That's why I'm thinking if I could just talk them into loosening up a bit they might start working again.

But who's kidding who, I'll be tearing down that engine in the next few days, unless the Rotary Gods intervene.

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!