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infernosg
infernosg New Reader
2/5/20 12:11 p.m.

I had the exact same thing happen with my first RX7. Although in my case it turned out the actual groove in which the coolant seal sits in the front iron blew out. Instant junk iron. I ultimately ended up building my own engine. Watched plenty of YouTube videos and bought the DVD from Mazdatrix. I also have a paper copy of the FSM I bought years ago. It really is pretty straightforward like everyone is saying and if it's a stock rebuild there aren't really any "gotcha" moments. The only special tools are the engine stand adapter and the flywheel nut removal tool (I have the big-ass wrench version). You'll also need feeler gages, a caliper and a dial indicator but I think most of us have those already.

 

All that being said, I'm probably not the best example. I blew my engine in April 2011 and didn't get the car running again until August 2017. Scope creep and all that. I couldn't have done that bad of a job though as my engine has to be nearing 10k miles since the rebuild and, if the last dyno is to be believed, is putting 240 hp to the rear wheels.

1988RedT2
1988RedT2 MegaDork
2/5/20 1:21 p.m.
Brett_Murphy said:

I just remembered: I think I might have the engine part of the Factory Service Manual floating around in my garage. If I find it, do you want it?

I actually own a copy of the Mazda RX-7 1988 Workshop Manual by Mazda.  It's kinda yellow-orange and measures about 9" x 6" x 3" thick.  Chapter 1 appears to cover disassembly, inspection, and reassembly of the engine.  So thanks, but I think I've already got it.  Guess I should start studying.  cool

 

Brett_Murphy
Brett_Murphy GRM+ Memberand UltimaDork
2/5/20 1:37 p.m.

In reply to 1988RedT2 :

Those studs are where the engine mounts go. They'll hold the engine.

Atkins makes an adapter, too.

I actually have this one, but it's currently on loan to a friend with a crippled RX-8.

WonkoTheSane
WonkoTheSane GRM+ Memberand SuperDork
2/5/20 4:18 p.m.

I have a copy of the Atkins rebuild DVD that I bought back in like 2000, I can get you a copy if you send me a PM.  I've rebuilt a few of em now (2 s4 and 1 renesis).  

Don't panic.  It's the easiest internal combustion engine you could possibly rebuild.  One I did in a weekend since I already had a seal kit and got lucky that there was no hard part damage.  Everything inside is on springs, so the clearances aren't as precise as a lot of piston engine bits.

If you don't feel that you have the time or room, though, there's no shame in subbing it out.

DaveEstey
DaveEstey PowerDork
2/6/20 5:19 p.m.

I did the 13b in my hillclimb car this summer. Not that hard. 

I used Rotary Aviation rebuild kit and fresh apex seals since I got fresh cermet coated housings. 

Brett_Murphy
Brett_Murphy GRM+ Memberand UltimaDork
2/6/20 6:09 p.m.

Who did you have do the cermet coating? There was a Canadian firm that was doing them, but back when I looked (90s) they would only take nearly new or new housings. I'd like to think that the process has gotten better since then.

1988RedT2
1988RedT2 MegaDork
2/6/20 6:12 p.m.
Brett_Murphy said:

Who did you have do the cermet coating? There was a Canadian firm that was doing them, but back when I looked (90s) they would only take nearly new or new housings. I'd like to think that the process has gotten better since then.

LOL.  I was just about to ask this question.

 

DaveEstey
DaveEstey PowerDork
2/8/20 7:05 a.m.

In reply to Brett_Murphy :

I got their last set. They don't do it all anymore - too expensive and a pain in the ass to lap it in I guess.

DaveEstey
DaveEstey PowerDork
2/8/20 7:34 a.m.

Just went back into my emails. They don't do housings any more but they do irons. 

1988RedT2
1988RedT2 MegaDork
6/6/20 4:39 p.m.

Well, a bump to this thread.  My son and I got to talking and he really wants to drive the RX-7 to school one day next year, assuming that they actually have school and all that so we went out to the garage and kicked some spiders out of their webs, moved some junk around and pushed the junk engine out into the daylight which it hadn't seen in ~15 years. 

I had it attached to the engine stand via the four fingers attached to points on the front iron, so while it's not ideal, it will allow a teardown.  We hit it with the pressure washer and cleaned it up a bit.  Then consulted the manual and started tearing it down. 

I had already pulled the flywheel and busted the front e-shaft bolt loose with an impact years ago.  All we had to do was remove the front cover and oil pump, then flip it over and loosen the through bolts, gradually, in order.  All 18 of them.  Took us a little while.  My son did all the wrenching.

A couple little bumps and a tug and we lifted the rear iron off.  Pretty cool to actually see inside of one of these remarkable engines.  My son commented that it was really small, and I had to agree.  It's an amazingly compact powerplant. 

We called it a day at that point.  I want to get a box or something to organize the seals and springs.  While the rear rotor and housing are both pretty trashed due to the broken apex seal, the rear iron appears to be in pretty good shape.  No evidence of corrosion.  I'm hoping the "good" engine currently in the car is in similarly good shape. 

So, progress!

Brett_Murphy (Forum Patrón)
Brett_Murphy (Forum Patrón) GRM+ Memberand MegaDork
6/6/20 7:48 p.m.

Tangible progress is always a great way to bump a thread after 4 months.

1988RedT2
1988RedT2 MegaDork
6/7/20 7:41 p.m.

We spent a little more time on it today.  I partitioned a box to help me keep track of the seals and springs, and we got the center iron off and the e-shaft out. 

The rear rotor housing is very trashed, as is the rotor itself.  One apex seal is missing completely, the other two sustained damage.  The rotor is scarred up and the apex seal grooves are pretty well buggered as well.

Pic of rear rotor housing.  Sorry for the lousy pic:

Brett_Murphy (Forum Patrón)
Brett_Murphy (Forum Patrón) GRM+ Memberand MegaDork
6/7/20 9:51 p.m.

Not sure if you know or not, but if you can't find turbo housings, and you can find NA housings, you can allegedly de-pin the exhaust sleeves for the Turbo turbo housings and put them in the non turbo housings.
 

1988RedT2
1988RedT2 MegaDork
6/8/20 7:01 a.m.
Brett_Murphy (Forum Patrón) said:

Not sure if you know or not, but if you can't find turbo housings, and you can find NA housings, you can allegedly de-pin the exhaust sleeves for the Turbo turbo housings and put them in the non turbo housings.
 

Good to know.  Is that the only difference between the two?

I'm hoping the housings on the "good" engine are okay, since it's still in running shape.  These irons do seem to look pretty good, so I'm optimistic that between the two engines I'll have enough good parts to get one good rebuild.

What's the best way to clean up the irons?

Brett_Murphy (Forum Patrón)
Brett_Murphy (Forum Patrón) GRM+ Memberand MegaDork
6/10/20 9:15 p.m.
1988RedT2 said:

Good to know.  Is that the only difference between the two?

I'm hoping the housings on the "good" engine are okay, since it's still in running shape.  These irons do seem to look pretty good, so I'm optimistic that between the two engines I'll have enough good parts to get one good rebuild.

What's the best way to clean up the irons?

I think other than the exhaust, the rotor housings are identical. It's been a while since I thought about it. I'm hoping somebody with more recent experience will chime in.

For cleaning,  using actual petroleum based cleaning solution is good for everything. I soaked mine in a tub of parts cleaner for a full 24 hours before I even started trying to scrub.
For the rotors: Use a broken apex seal to clean the apex groove, a broken side seal to clean the side seals. Old apex seals are good for the oil control rings and corner seals, too.
For the irons: Use whatever will fit in the gasket groove and other places and clean it until you're not afraid to eat off of it. Really scrape at the bottom corners of the seal channels and gasket channels without bunging up the edges. 

RXBeetle
RXBeetle Reader
6/12/20 10:35 a.m.
1988RedT2 said:
Brett_Murphy (Forum Patrón) said:

Not sure if you know or not, but if you can't find turbo housings, and you can find NA housings, you can allegedly de-pin the exhaust sleeves for the Turbo turbo housings and put them in the non turbo housings.
 

Good to know.  Is that the only difference between the two?

I'm hoping the housings on the "good" engine are okay, since it's still in running shape.  These irons do seem to look pretty good, so I'm optimistic that between the two engines I'll have enough good parts to get one good rebuild.

What's the best way to clean up the irons?

The NA housing trailing spark plug hole is slightly higher. That still shouldn't stop you from using them though. The exhaust sleeve is pretty difficult to remove. You have to pull 2 blind roll pins out. I've had success with a small wood screw and mig welding into a nut on a stubborn one. You can also grind out the diffuser in the NA sleeve but they are inconel I believe, carbide burs and patience required. You don't need to pull the sleeve from the housing to do this. 

1988RedT2
1988RedT2 MegaDork
6/12/20 10:46 a.m.

Atkins claims to have these in stock at $625.  That's not a trivial amount of money to me, but I think I'm okay with spending it.  I only want to do this once. laugh

Hoping that I have two good rotor housings on my current motor, and two good rotors.  It's the irons I'm a little worried about, as the coolant change interval on this car has been irregular.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
6/12/20 12:05 p.m.

Mazda futzed with spark plug location for every iteration.  Racing Beat used to have a chart of optimal ignition timing based on which rotor housings you had.

 

The Turbo II rotor housings also had a coolant passage drilled out for (IIRC) the front rotor.  You can leave that blanked off so the intake manifold gets no heat, or if you really wanted to you could drill the passage.

Double check the passages to and from the exhaust ports, series 4 nonturbo had EGR as well as air injection. Mazda kept changing up how the air injection passages were laid out, some went in through the ends, some went in through the intermediate.

 

Knock sensors!  Some engines had them on the rotor housings.

1988RedT2
1988RedT2 MegaDork
6/27/20 2:13 p.m.

Argh!

Just about ready to pull the "good" engine.  Got the rear oil cooler line disconnected no problem.  Can't get the front one loose.  Doesn't make matters easier that I don't have any skinny metric wrenches that big.  Is there a trick to it?  It's like a fitting threaded into the engine and a hose fitting threaded into that.  I can't get the two fittings to move relative to one another.  Guess I'll have to pull it loose at the other end. 

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
6/27/20 2:48 p.m.

No, they suck.

1988RedT2
1988RedT2 MegaDork
6/27/20 4:03 p.m.
Pete. (l33t FS) said:

No, they suck.

On a related note, does anybody sell a set of metric wrenches starting at say, 21mm, and going up to like 32mm?  Or do I have to buy them one at a time eachies?

1988RedT2
1988RedT2 MegaDork
6/27/20 7:29 p.m.

Well, my homemade sheetmetal wrench failed to apply sufficient torque.  I will beat my head on it some more tomorrow.  Maybe it's just the concussion talking, but it seems that now might be a good time to get rid of that top-mount intercooler and go front-mount.  I already have the requisite plumbing.  Well, most of it, including the throttle body elbow.  If I pull the A/C condenser, I should be able to fit a good-sized I/C in there, no?

Brett_Murphy (Forum Patrón)
Brett_Murphy (Forum Patrón) GRM+ Memberand MegaDork
6/29/20 10:24 a.m.

Hmmm. I am guessing if you got RX-8 dual oil coolers and found a way to mount them in there, you could put an intercooler where the stock oil cooler is now.

1988RedT2
1988RedT2 MegaDork
7/8/20 4:58 p.m.
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