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

 

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.