?Hillybilly method for compression testing?
09-26-12, 08:33 AM
#26
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.
09-26-12, 08:31 PM
#31
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.
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.
09-27-12, 06:55 AM
#34
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:
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:
09-27-12, 08:23 AM
#36
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).
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).
09-27-12, 10:12 PM
#38
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.
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.
Last edited by Qingdao; 09-27-12 at 10:15 PM.
09-29-12, 05:37 PM
#39
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.
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.
09-29-12, 09:37 PM
#40
I really should 
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.
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.
09-30-12, 07:27 AM
#42
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
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
09-30-12, 10:36 AM
#44
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
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
At these prices, I have several used and new rotor housing I'd sell at close to the same price.
Cermet X refinishing service $750ea
Cermet A refinishing service $545ea
Cermet B refinishing service $350ea
Chrome grinding service $150ea
10-01-12, 08:27 AM
#45
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.
10-01-12, 11:40 AM
#46
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.
10-01-12, 01:52 PM
#47
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'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?
10-01-12, 08:06 PM
#48
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'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?
