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codrus (Forum Supporter)
codrus (Forum Supporter) GRM+ Memberand UberDork
7/16/20 3:28 p.m.

Yes, you need heat, lots of it.  On the junk motor I took apart, I needed about 5 minutes with the MAPP torch.

(Edit: sounds like you got it apart, cool.)

1988RedT2
1988RedT2 MegaDork
7/16/20 3:31 p.m.

In reply to codrus (Forum Supporter) :

That would have been the next thing to try.  I only have propane, so not sure that was going to do the trick.

Glad we were able to get it off with the brute force method, and I didn't break any more tools.

RXBeetle
RXBeetle Reader
7/16/20 6:52 p.m.

Be aware all the hammering, especially axially to remove the flywheel, transmits forces through the torringtion thrust bearing that sits behind the front balancer. If there are any  impact marks on the races they have to be replaced. I have a set in my pile-o-parts if you need some. If you keep it all as is you should still have in spec end play (still check), start mixing thrust bearing parts and you will probably find end play out of spec and need a different size spacer to get you back.

1988RedT2
1988RedT2 MegaDork
7/16/20 8:34 p.m.

In reply to RXBeetle :

Yes, I am aware, and it was for that reason that I didn't go all Neanderthal on it from the get go, but rather gradually increased the size of the "hammer".  I had heard that the clunk from a heavy bit of wood would be less likely to ding delicate parts.  Hoping that's true.  Thanks for the info and the offer of parts. smiley

1988RedT2
1988RedT2 MegaDork
7/17/20 2:18 p.m.

Does anyone have any helpful advice, or maybe you can point me to a video, regarding the thorough cleaning of housings and irons?  I envision a few big plastic storage bins full of cleaning solvent so I can soak the housings completely immersed.

What solvent?

j_tso
j_tso GRM+ Memberand Reader
7/17/20 2:57 p.m.

Here's one: https://www.youtube.com/watch?v=U5A5q61bzRI&list=PL06C7C4B54765998D&index=5

On the housings you can use lacquer thinner or similar solvent. Don't scrub with anything too rough like a wire wheel on the combustion surfaces.

The easy way to clean the rotors is to submerge them in a bucket of Purple Power for a day.  A harsh solvent may eat away the coating on the bearing, so if you try a bucket of carb cleaner make sure it's "babbit safe".

1988RedT2
1988RedT2 MegaDork
7/17/20 3:36 p.m.

In reply to j_tso :

Cool, thanks!

I've watched several of aaron's videos already.  Informative and entertaining. 

sevenracer
sevenracer Reader
7/18/20 9:07 a.m.

I've always been concerned about damaging the bearing coatings with cleaner.  I use Purple power in a tupperware container and soak then clean each face of the rotor separately - keeping the fluid level in the container below the bearings.  Then the same thing with each side of the rotor - keeping the level of fluid low enough that the bearings aren't soaking.

 

I have fully submersed and soaked rotors before, and the bearing surfaces definitely changed to a much darker color.  They may still be fine, but I never used a set like that.

1988RedT2
1988RedT2 MegaDork
7/18/20 9:23 a.m.

In reply to sevenracer :

Noted.  Thanks!

1988RedT2
1988RedT2 MegaDork
7/18/20 1:09 p.m.

Any other solvent recommendations?  A bit of sleuthing around the internet brings up discussions of a variety of solutions including a mixture of mineral spirits and kerosene. 

Recon1342
Recon1342 Dork
7/18/20 3:29 p.m.
1988RedT2 said:

Any other solvent recommendations?  A bit of sleuthing around the internet brings up discussions of a variety of solutions including a mixture of mineral spirits and kerosene. 

Try a citrus based degreaser like Citrol or big orange. It's fantastic on petroleum products, but will not eat o-rings or gaskets. I've not seen anything like it for varnish deposits. Here's a before/after on a carburetor float bowl that spent 30 years covered in varnish- took about 45 seconds to dissolve the varnish right down to aluminum.

RXBeetle
RXBeetle Reader
7/19/20 10:03 a.m.

 

In reply to 1988RedT2 :

I did an overnight ATF soak and scrub with a brass brush. Side seals were still really stuck but I don't know if any other solvent would do better. I'm not a fan of using corrosives unless I it's really proven safe. 

 

1988RedT2
1988RedT2 MegaDork
8/7/20 3:01 p.m.

Wow.  Over two weeks since I touched this thing.  Life is complicated.

Number One Son and I opened up the keg today.  What we found was not good.  Cost of the rebuild just went up. 

Brett_Murphy (Forum Patrón)
Brett_Murphy (Forum Patrón) GRM+ Memberand MegaDork
8/7/20 7:12 p.m.

Ah, the infamous coolant O-Ring failure thing.

Are irons still a lot cheaper than rotor housings, or has the supply dried up?

1988RedT2
1988RedT2 MegaDork
8/7/20 7:49 p.m.
Brett_Murphy (Forum Patrón) said:

Ah, the infamous coolant O-Ring failure thing.

Are irons still a lot cheaper than rotor housings, or has the supply dried up?

Alas.  It appears to be the other way 'round.  Center iron looks to be $1000-$1100, if anybody has one.

I have the other one, which looks okay, but I haven't checked it with the feeler gauges yet.

Rear iron looked okay.  Some edge flaking on the rear rotor housing, middle iron totally borked, front housing looks okay. 

I was really kind of expecting, hoping the hard parts were going to be okay.  I didn't think it would run as well as it did with that big of a hole.  Crazy that it just blew out there.  No signs of corrosion really, though the o-ring was definitely tired.  It just broke that piece of iron right off.  I guess that is in the area of maximum pressure.

j_tso
j_tso GRM+ Memberand Reader
8/7/20 7:54 p.m.

Maybe $1000 new, here are a couple I found on ebay:

https://www.ebay.com/itm/1989-Mazda-Rx7-S5-13B-TURBOII-CENTER-IRON-2/402285531908?hash=item5daa161304:g:g-AAAOSwadhe2a1D

https://www.ebay.com/itm/Mazda-13B-Intermediate-Side-Housing-RX7-Rotary-FC3S-Turbo-4-Iron-FD3S-20B/383475136001?hash=item5948e63601:g:pRUAAOSwC7NebeSO&autorefresh=true

Other than coolant seal grooves, just need to check for flatness with a feeler gauge and straight edge, and then step wear with a dial indicator.

1988RedT2
1988RedT2 MegaDork
8/7/20 9:01 p.m.

In reply to j_tso :

That one in Japan looks different from my S4.  Is the S5 center iron identical?  I think S4 to S5 was where they went to lighter rotors?

Snrub
Snrub HalfDork
8/7/20 10:07 p.m.
1988RedT2 said:

In reply to j_tso :

Cool, thanks!

I've watched several of aaron's videos already.  Informative and entertaining. 

A number of years ago I was present as he rebuilt his first rotary engine. He knew every torque spec, wear spec, tolerance, etc. by memory, just because he read it a couple of times a week or two prior. Impressive brain in that head of his.

j_tso
j_tso GRM+ Memberand Reader
8/7/20 11:56 p.m.

In reply to 1988RedT2 :

The different irons will bolt up together. I'm not sure on other physical differences other than that S4 and S5 Turbos had the knock sensor moved from the center iron on the S4 to the rotor housing above the spark plugs.  Otherwise they should be compatible.  Not sure on the weight but both turbo and non-turbo S5 rotors are higher compression than S4, makes no difference which housings are used though.

Brett_Murphy (Forum Patrón)
Brett_Murphy (Forum Patrón) GRM+ Memberand MegaDork
8/8/20 9:12 a.m.

Somebody posted in another thread that there are quite a few TII engines on ebay cheap right now.

1988RedT2
1988RedT2 MegaDork
9/4/20 6:53 p.m.

Progress has been slow.  Got the rotor housings cleaned up a bit today.  I would like someone to assess them.  I am concerned with the matte, silvery-gray appearance of the surface.  It appears that most of the plating is worn away?  It would be great if someone with some rotary building experience would offer their evaluation.

Front housing:

 

Rear housing:

 

 

1988RedT2
1988RedT2 MegaDork
9/4/20 7:06 p.m.

By contrast, this is the surface just above the spark plug holes on the Front housing:

1988RedT2
1988RedT2 MegaDork
9/4/20 8:23 p.m.

Funny that the line around the center of the housing that I at first thought might be some sort of scoring is actually a line of lesser wear in line with the oil metering injection port.  Drawing my finger across the housing, I can feel the center as a high spot.  I will need to consult with the factory manual and see what is acceptable there.

While these housings appear to be undamaged, there is a good chance that they are simply worn out.

RXBeetle
RXBeetle Reader
9/4/20 9:33 p.m.

Is it pretty flat across the housing? Can you feel any wear grooves? It doesn't look like there is cracking around the plug hole and the chamfer is not worn down. There isn't much flaking on the edge either. I clean up my housings with a 1/2" round 600 grit oil stone. You have to be really careful to hold the stone straight so you don't crown the surface. Really not trying to remove much material, just knock any high spots off and make it a lot easier to judge how bad the wear is. You may also want to measure the height of the apex seal to get an idea of how much wear and abuse it has seen. 

I have an S4 NA center iron. I'm not sure if it will work with your build plan, intake closing is 10deg earlier (that can be remedied) and egr port is up top (can be blocked). Let me know if you're interested and I'll get you some pics and inspect for wear and of course coolant seal groove. 

1988RedT2
1988RedT2 MegaDork
9/5/20 10:53 a.m.
RXBeetle said:

Is it pretty flat across the housing? Can you feel any wear grooves?

 

It's not that flat.  There's that higher ridge in the center that I can feel with my finger.  I've laid a short piece of copper pipe (presumed straight) across the surface and if I shine a bright light under it I can see a gap on either side of the center--gotta be several thousandths.  I need to find my feeler gauges and see if I can quantify it.

Seems like new apex seals would not seal well at all, and I'm pretty sure I won't bother putting this together with the old seals. 

This project gets more expensive everytime I look at it.... sad

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