Reassembly

The FSM lumps some reassembly preparation items into other sections of the guide, like Inspection, but I think the rotors deserve their own topic.

First, slide an apex seal into each groove, and a side seal each side seal groove, to make sure they slide in smoothly. Note that you're not looking for any PLAY, but they shouldn't stick, either. Check the apex seal lengths with a digital caliper or micrometer, and their clearance within the slot with a feeler gauge. If they don't slide smoothly, use a thin, fine-toothed file to gently remove any remaining carbon deposits in the grooves.

Fig. 1: Clearance Test

Fig. 2: Gentle filing

Fig. 3: Jeweler's file

Next clearance the side seals. Install two corner seals, and place a side seal in the slot between them. Since they are/should be new, it won't fit. Sand the end, keeping the factory-supplied angle, against a sheet of 400-grit sandpaper laid flat on your table. Remove just a bit of material at a time. The FSM calls for 0.002”-0.0059” of clearance here. I sanded mine until I could just slip a 0.003” feeler gauge between the side seal and corner seal.

Finally, install the oil control rings. Lubricate each oil control O-ring (I used assembly lube, but engine oil is fine, per the FSM) before installing the oil control rings. Note that the springs that go under the rings are installed in a very specific way, to prevent them from rotating as the rotors spin:

• Springs marked with cream paint are the FRONT FACES of the front and rear rotors
• Springs marked with blue paint are for the REAR FACES of the front and rear rotors
• Each spring has a rounded end and a square end, set at an angle to the spring. The rounded ends go DOWN, into small round holes in the rotors. That keeps them from spinning. The flat ends go UP, into small flat depressions in the backs of the oil control rings. Make sure you install them this way!

Attach the front iron¹⁾ to your engine stand. Take a moment to inspect the inside face and verify that it's ready to use, because from here on you aren't going to want to touch it much!

Then flip the housing over and install the thrust plate as follows:

1. Coat the inside mating surface of the flange on the front stationary gear (the area around the bolt holes) with sealant - I used Permatex Ultra Black.
2. Coat the matching surface on the front housing as well.
3. Set the stationary gear in place, and press down to seat it properly. Tapping gently with a hammer can help if it gets stuck - it's an engineered fit.
4. Coat the front thrust washer liberally with oil (I used engine assembly lube), and set it in place on top of the stationary gear. The chamfer on the washer faces the front housing.
5. Coat the needle bearing liberally with oil, and place it on top of the thrust washer.
6. Place the top plate on top of the stack, and bolt it down, first to hand-tight all around (to seat the stack properly), then to 12-16 ft-lb using a torque wrench.

Fig. 4: Front iron on stand

Fig. 5: Assembly diagram

Fig. 6: Front iron flipped

Fig. 7: Front stack installed

The other tool you can see in the lower-right photo is my tap. I used this to do a final clean-up on the threads of the bolts before I re-installed them. This is actually the safest option for cleaning used threads. Abrasives can leave scratches behind that weaken the bolt.

The FSM calls for this step to be performed during the assembly process, but I found it helps to prepare it ahead of time. Just like the front iron, the rear iron holds a main stationary gear. However, this time there's no “stack”. Instead, there is an O-ring in a groove where the gear meets the rear iron, and a large rubber oil seal.

I departed from the FSM slightly here. Several builder resources advise applying a thin film of sealant (Permatex Ultra Black is good) to the outside edge of the oil seal and its mating surface on the iron, before pressing it in place. This both provides additional sealing for this critical area and eliminates the need to hammer the seal in. The sealant lubricates the seal, allowing you to press it in by hand, reducing the risk of damaging it.

Fig. 8: Rear main oil seal

Fig. 9: Oil seal installed

Fig. 10: Rear iron, flipped

Prep the front rotor by installing the corner seal springs, corner seals, side seal springs, and side seals.

Fig. 11: Corner seals

Fig. 12: Side seals

Fig. 13: Aligning seal groove

Next, as shown below, use a syringe or other tool to apply a bead of Crisco (Vaseline is fine, too, but Crisco won't melt as quickly on a hot day, and drop your O-rings out of their grooves!) in both water jacket O-ring grooves. Lubricate the appropriate O-rings with the same lubricant, and feel along them as you do so for the lumps. The lumps should go in the “cold” region at the top of the housing, just past the intake region (see the FSM). Lubricate the face of the iron, the stationary gear, and the front face of the front rotor, and lower it into place. Make sure the rotor has one apex seal facing the bottom of the engine.

Fig. 14: O-ring lubricant

Fig. 15: First rotor installed

Double-check your eccentric shaft to be sure your oil jets are the way you want them. Also, prep the rotor housing (you may as well prep both at once) by placing lubricated O-rings over the upper dowel holes, front and rear (should be four O-rings, two per housing). Then place the rotor housing over the front rotor and the eccentric shaft in place.

The FSM vaguely shows two areas that require sealant. You can tell which ones they are because there are small grooves machined into the rotor housings in those areas to hold more sealant (you should remember cleaning dirty grey sealant out of them when you disassembled the core). Don't forget to brush on sealant here! If you work quickly, you can do both rotor housings at the same time. But be warned: once you apply sealant, don't stop for a break until you torque down the bolts! If it hardens, you'll have to disassemble the stack, scrape the sealant off, and start over again.

Fig. 16: E-shaft double-check

Fig. 17: Sealant on first housing

Now install the corner seal springs, corner seals, side seal springs, side seals, apex seals (if they aren't already in place) and apex seal springs.

The apex seal springs can be a little trick to get in, particularly the little ones. I found that a large spring makes a good “pusher” for a small spring. Also, you can pull the apex seal up/out a bit (about an inch seemed to work well for me) so you can better tell when the small spring is in the correct position.

Lubricate two dowels and slide them into the dowel holes in the top left and bottom right of the rotor housing. They should go all the way through and into the front iron, leaving about 3/4” protruding to position the center iron.

Fig. 18: E-shaft installed

Fig. 19: Corner seals installed

The center iron has front and rear water jacket O-ring seals just like the front iron. Set those up the same way, and as with the front iron, lubricate the face where the rotor will ride. When you install it you need to lift the eccentric shaft about an inch and a half. I found it was easiest to do this ahead of time with a board or other shim, then lower the center iron down, then lower the eccentric shaft back down.

The rear rotor installs in exactly the same way as the front, just be aware that you start by installing side/corner seals on the FRONT of both rotors. For the front rotor, that meant the side with the gear. For the rear rotor, that means the OTHER side! Don't forget to apply sealant to the lower corners of the housing legs, front and rear, lubricant to the dowel O-rings, front and rear, lubricant to the faces of the irons, and lubricant on all surfaces of the rotor.

Finally, install the bolts. Make sure you place a new sealing washer on each. Then brush a small amount of anti-size compound on the threads, and RTV on the center 1.5” or so. Install each bolt hand-tight. Then, go around and tighten each bolt to just UNDER the 24-28 ft-lbs the FSM calls for, to help seat everything in the stack and squeeze out any excess sealant. Finally, torque each fastener down to the FSM's required 24-28 ft-lbs. Note that the FSM calls for a specific order in which the bolts should be tightened. Don't ignore this!

Fig. 20: Stack fully assembled

Once everything cures and settles, you can do a cooling system pressure test. You'll need to block off the ports first. I didn't get a photo of this, but make sure you plug the water temperature switch hole too - the switch itself makes a great plug!

Fig. 21: Heater Port Plug

Fig. 22: Heater Port Plug

Then install the pressure test tool, pressurize the system, and let it sit for an hour.

Fig. 23: Pressure Test Tool

Personally, I wasn't overly thrilled with this tool. My air inlet valve was left loose, and no matter how much I tightened it myself it still leaked a bit around the valve seat. I eventually stripped it trying to get it to stop leaking. I later discovered a small bit of rubber gasket material from the tool's sealing gasket trapped under the seal. On the other hand, now I know my block is solid. I shouldn't NEED the tool again.

You could easily build this tool yourself, by the way:

1. Cut a block of 1/4” aluminum to fit over the water pump pad, and drill two holes for bolts at the appropriate spots on the top and bottom of the pad.
2. Drill two holes in the face, tapping one for a pressure gauge and sizing the other for an air valve, which you can get at McMaster or elsewhere.
3. Cut a piece of sheet rubber to act as a gasket for the back, then cut two holes in it where the pressure gauge and air valve sit.

First, you need to check your end play. Start by installing the rear counterweight and flex plate, as the end play is partially determined by this part of the stack.

Note that there are two flex plates commonly available for this engine; you need the 88-91 version. Most components are similar from 88 through 95, but not this one! See the photos below. The RD-1B mounting plate will ONLY fit the older-model flex plate.

Fig. 24: Wrong flex plate

Fig. 25: Correct flex plate

Lubricate the rear main oil seal, install the counterweight, then install the flex plate. Note that the flex plate should come with a spacer - be sure you mount this on the correct side (it goes on the rear). This is illustrated in the FSM on pages C-78 and C-82.

Now flip the engine back over and assemble the front stack per the FSM. Be very careful when inserting the spacer to make sure it slips down cleanly in the center of the needle bearing at the bottom of the stack. Then check your end play using a dial caliper. Adjust your spacers as necessary to have the correct amount of end play. You may want to review this article on end float. It includes a diagram of how the spacers and bearings work together to provide play in the system. (You must join to view the picture, but it's free.)

Once your end play is correct, reinstall the stack with the oil pump drive chain and oil pump, bolt down the oil pump, and clean the mating surfaces with acetone. Install the oil pressure valve in the front cover, and the front main oil seal. (As with the rear oil seal, lubricating it with some Permatex will help make it easier to install it, and will improve its seal at the same time. Be sure you only use a thin coat and only on the outside of the seal.)

Although it's not necessary, you can remove the oil metering pump drive shaft from the front cover. This is the part that engages the helical gear on the eccentric shaft. If you pull the rod out a bit you can remove a snap ring, then pull it out more to remove the other snap ring. Save this somewhere safe in case you ever want it again. Some builders skip this step, but it saves a few ounces so I think it's worth doing.

If you have a front cover gasket, hang it on the wall. Nearly every guru I've researched advises against using it. Although Mazda improved the 3rd-gen setup, past rebuilders have had problems with sudden loss of oil pressure after some run time. The front cover oil passage O-ring fails because the front cover gasket in the rebuild kits isn't the right thickness. The solution is simple: use a better O-ring (Pineapple includes one in their kit) and use Permatex Ultra Grey as a sealant rather than the gasket. Brush on a thin coat of this on the front cover mating flange, then bolt down the front cover. Finally, install a cover on the oil metering pump pad, using Permatex to seal it.

Fig. 26: Rear Counterweight

Fig. 27: Black Sharpie, pre-impact-wrench

Fig. 28: Yellow safety stripe (nail polish)

Fig. 29: Partial Front Stack

Fig. 30: Front Cover

Fig. 31: Oil Pump Installed

Fig. 32: Front Cover Installed

Fig. 33: Pulley Boss in Position