Just tore down the keg, I snapped some pictures hoping some of y'all could chime in on the state of my irons, housings, and rotors.

Motor has never been opened as far as I know, no signs of porting. About 125,000 miles. Was working perfect prior to disassembly
I wiped the parts down with a paper towel I had lying around, other than that no cleaning as of yet. I have an Amazon ultrasonic cleaner I'll be putting everything into to clean as much as I can, along with CLR/brakleen, brushes for the non-chromed surfaces, etc..
I plan to do either a big Street port or half bridge, nothing too insane.

Looking quickly they seem to be in pretty darn good shape. no devil's nail marks, no de-chroming. Decent "cloudy reflection" on chromed surfaces
Outer water jacket seals came out in one piece
Inner water jacket seals came out in many pieces. A long inner strip, long outer strip, and the actual orange came in small pieces
Apex seals were 3 piece, didn't see any chips. One or two sides seals were a little tough to remove, spring too, figured just carbon build up
Oil control rings are still pretty black but i need to give a better look
One coolant passage had a huge glob of wet rusty goop (engine has been sitting for quite a while)

Thank you for any advice.


Rear Iron

Rear rotor

Rear housing

Middle iron front

middle iron rear

e-shaft

e-shaft reverse

front housing

front iron

everything

 

Those are good enough to keep cleaning
i think you want a street port, the bigger the port the more all of the other things matter, exhaust turbo, etc

 

I don't have experience rebuilding rotary engines, but I'm interested to hear your thoughts about your ultrasonic cleaner. I've been thinking about buying one with hopes of it being useful in a future engine rebuild, but not sure what size would be needed to clean the big parts like rotor housings and side plates. If I had my engine apart, I would try to address the coolant jackets near the spark plugs, as described in this thread by Barry Bordes: https://www.rx7club.com/3rd-generati...em-fix-989811/

 

So far I used it on the rotors, saved a lot of time on scrubbing and brushing, knocked off a lot of carbon and oil. I used it on the Lower intake manifold as well prior to the engine and it really released a lot of stuff in the hard to reach nooks and crannies.

As for the housings and irons. My plan is to have them in and to half at a time since they're just barely too big to submerge completely.

It heats to 170 degrees and then does up to 30 min of ultrasound, the heat helps break up the oils as well. Right now I don't have ay specific cleaners, just water with a bunch of Dawn

 

that sounds a LOT better than scrubbing for 12 hours

 

Hit the rotors with my brass brush, made quick work of what was left after 30 min each side (F/R) in the ultrasound.

Matching rotors!! Both "E"

The only concerns so far, a few deep ish scratches in the rear rotor face. It's only this one face. Located near my thumb and lower on the same side. Not other scratches noticed on either of the Rear Irons, or the housing.

 

All looks like a very typical engine for the age.

Doesn't look like coolant was regularly changed. Doing once a year or so coolant flush/fills makes a BIG difference. Rebuilt an engine for a friend with a 1990 convertible with 160k on the original engine - rotor housing coolant passages were bright aluminum. Discoloration is OK but that can also show that you may have other issues with corrosion in the coolant passages.

The last rotor pic - is that a round mark in the upper left?

General nicks and spots on a rotor face are fine. As long as they are smooth and no sharp edges/burrs. They will immediately fill with carbon on engine start.

With soaking in the ultrasonic cleaner, I know some cleaners/degreasers can degrade or remove material from bearings. I'd definitely give a good check over on the bearings if you are going to re-use.

Dale

 

Thanks Dale,
yes that spot is rounded in a weird way, but no other odd shaped gouges or any evidence on housings and irons, just that one rotor face

i'm planning on changing the bearings, and will do better about changing coolant

 

That motor has been rebuilt at another time as "witnessed" (hahaha) by the marks left last time it ejected apex seal pieces.

Get a copy of a Mazda manual.
Mazda recommends NOT to change bearings on a rebuild unless they are really worn (and Mazda will guide you on whats wear vs whats a "broken in" puzzle lock joint.

A fresh bearing is most likely to seize from oblong shape from how the bearings are made combined with pressing them in.

 

Thanks BLUE TII, good to know, and your point makes sense.
Now that I'm getting parts cleaned, the housings are much more reflective than they appeared to be, especially near spark plug mountain. I'm hoping they're still usable but I may just have to bite the bullet and buy 2 housings while they're still available, irons too while supplies last....

Pics below of how shiny the housings are

 

I can buy this ^ for the rotor bearings possibly. For the stationary gear bearings I'd absolutely replace them on a new build unless they were recently replaced. They have less surface area and see more stress. They're also a bit easier to press in and out once you have the procedure figured out.

Over the years I know of more than a few folks that chose to stick with their existing rotor and stat gear (main) bearings partially due to not wanting to tackle the headache. At least one spun a bearing after 8k miles of pretty standard driving, pretty expensive experience on a fairly fresh "complete but not complete" rebuild.

Agreed with Dale, first pic I saw of the first rotor housing and thought "man the previous owner did not believe in coolant changes." Evans all the way baby!

 

I'll take that advice. I'll have multi window bearing put into the stat gear, and keep the rotor bearings. Doesn't look like any copper showing on the Rotor bearings.

I have some valve lapping compound and a orbital buffer I'm going to hit the irons with, and I'm looking at sending the housings out for refinishing to Freelance or maybe Chips (still hesitant after false advertising on water pump adapter), worse comes to worst I'll send to REC in Canada- cost more to ship than to service...

I grabbed Mazdatrix full bridgeport template, but I'm not doing the bridge part, just the normal port, got Racing Beat's streetable exhaust template as well, put the intake manifold gasket against the irons and sprayed Dykem and am porting them as well - as per Mr. Howard Coleman's advice, Porting isn't new for me, my Dremel and I were very busy when I had a WRX.

Dremel will also be cleaning the crap out of the coolant passages, wire wheel is doing a great job so far, then I'll do the jacket 'ripples' near the plugs.

Yes, will be going with Evans once it's back together

 

I'd run far away from Chip!
Pretty sure if you search there is a thread about him and how he fell off big time!
Goodluck with the build.

Steve

 

https://www.rx7club.com/midwest-rx-7...sport-1164583/

 

as Dale commented, looks like a pretty typical motor. my primary concern re your rotor housings is the cracks at the spark plug boss. not fixable and a disqualifier as to rebuild unless you are only going to the grocery store. otherwise the housings should be sent to Adam at REC for cleaning/honing. no one does it better and there is a difference between an Adam hone and most others.

 

Thank you @Howard Coleman I contacted Adam and am awaiting reply. I didnt notice cracks at the spark plug holes, i will look closer.

 

Yeh, not surprised after the water pump adapter i returned to him not having the o ring it claimed and being shipped in another car's tie rod end box wrapped in shop towels.. Awaiting REC response, also talking with Freelance, and Goopy is actually drivable distance away.
Overall I'm in no rush, the only thing that makes me want to move quickly is availability of parts given the state of Mazda....

 

I sent Housings and Rotors to Adam at REC. Honed and cleaned the housings, and chamfered out the cracks at the spark plug boss. Adam said the areas above the exhaust ports (didn't post a pic) are of some concern as there were scratches that couldn't be fixed. I'll post some pictures of his amazing work soon.

Thanks to all for the incredible advice.

 

 

ooo shiny

 

Adam ++

 

Why are the chamfers wider laterally than circumferentially? I would have thought they'd be better if they were longer along the circumference. Is that because of the "spark-plug-mountain"?

 

That's where the bosses were slightly cracked