Forum member ugabuga sent his engine for rebuild. He said it had 55k, but it is a mazda reman. It looks like it was one of the "good" remans, too, with mostly new parts and properly assembled without gobs of sealant everywhere.

 

whoops....

 

As you can see you chipped a chunk off of one apex seal, which flew around and pinched the next one until it also broke. Luckily the chunk somehow exited the engine with zero damage to either iron, which is unusual. He really dodged a bullet there.

Looks like everything is probably okay except the front rotor housing. The front rotor can PROBABLY be doctored up and reused, but I won't know for sure until I can media blast it clean and then try to file on it and reset the apex slot clearances.

 

rotors look really clean on the sides--was side seal clearance tighter than oem?
Doesnt look like it had any heat issues at all.
Bearing wear also looks better than a lot I have seen.
History on engine?

 

Hi, that is very interesting. 1st time I see that step by step like that. Not sure exactly how everything should look, but is the carbon build-up everyone talks about just on the rotor, or does it get on the housing too? Please forgive my ignorance. Thanks for posting pics.

 

Bit of scouring on the side plates. Could these be caused by the seals?

I assume when the spring is fully compressed it could protrude out a bit from the corner seal or cause the corner seal to move out causing the scouring mark. It is just a wild theory comming from someone who is still learning about rotaries.

 

I'm just in the middle of my own first rebuild. From what I've learned thus far if I pulled a rotor that looked like that out of my engine I would've thought it absolutely needed to be replaced. I thought gouges like that can create hotspots and ultimately detonation and yet again more seal destruction, no?

 

the engine is actually in decent shape, if we can know the history of it that will be better

 

All I was told is that it was an rx8 engine being sent to me for rebuild.

And then in person I could tell it was a reman.

Side seal clearance seemed to be around 10-15 thou...way higher than I like it.

 

I'm not a believer in that theory, personally. In fact IMO you are far more likely to have localized hotspots due to (natural) carbon formations than from a recessed metal hole, scratch or gouge.

 

The seals constantly wipe the rotor housing and iron wall surfaces, so normally you should see perfectly clean surfaces there. The rotor itself touches nothing, (like a piston in a regular engine) and so carbon builds up on it.

 

What?

That made about as much sense as a "buy 1 for the price of three, get 1 free" sale.

 

Thank you very much! "Knowledge is good", Emil Fabir.

 

oh wow. never seen broken seals like that. that one housing certainly needs replacing.

 

as always thanks rr for posting pics

 

Update: engine is built.

Parts cleaned and ready...








Rotors nice and cleaned up.





Owner got lucky because even though he broke apex seals and destroyed a rotor housing, the damage to the rotor was light enough that I could salvage it by filing and restoring the apex slot clearance. This saved the cost of a replacement rotor at roughly $250 used or $700 new.








Obviously he had to have a replacement rotor housing, and I came up with a close match in terms of surface condition/wear to his other surviving original. I also do a little touch up work to the leading spark plug holes on all the rx8s that I build (unless they are new rotor housings) to hopefully mitigate some of the swelling and cracking that happens in that area.

 

Irons cleaned up...







Seals installed in the rotors.





Nice side seal clearance....




Assembly...

 

First endplay check...




Assembled front stack...




Coolant system pressure test...





Post assembly endplay verification.




All done...

 

Work of art RR. Great job on that rebuild.

 

Great Job RR. Looks like the work of a master rotard haha. I'll definitely be coming to you when I need a rebuild, no telling when that'll be. Compression is in the 7s and has stayed there since I started pre-mixing, so..... fingers crossed!