hawcer

My son picked up a 2004 rx-8 automatic from a car lot. they had it over a year. it wouldn't start and was completely flooded. he read around and hoped it was just flooded from moving it around the lot and not letting it get warmed up. The mileage is 100,000 and change.

I had it towed to my shop to see what was up. I cleared thee flood and got it started. smoked like a freight train and only seemed to be running on one rotor.
Not having the necessary tools to do a compression check the correct way...I resorted to a standard compression gauge just to see the differences between the two rotors. the front rotor puts out 125psi and the rear has 0. it's also belching back up into the intake. cylinder leak test( I know, I know) has leakage into the intake and exhaust on the rear rotor.

If I tear into this what should I expect to find? At the moment I'm thinking a JDM replacement would be the best bet considering the costs of rotors, housings and rebuild kits.

What say you?

Loki

iTrader: (1)

Yeah 0 compression is a pretty strong indicator.
JDM could work but you need to make sure it's a 4 port (so the low power version) and that it's not in the same shape as one you have

I think if you tear into it, you'll find a broken side seal and perhaps apex seal in the rear rotor.

If you want a reliable rebuild, I'd look at buying one from Rotary Resurrection, Pineapple Racing or another reputable rebuilder. If it's a money question, you might want to just part it out. That 125psi front rotor might have parts worth something to a rebuilder and 4-port parts are becoming rarer.

If your son is set on an RX8 get an 06+ if it must be an automatic. Manual if he wants the high-power motor.

hawcer

He got it cheap and knew it could need an engine. other than that it's in great condition. I remember my dad loved the old rx2,rx3, and rx4's....pulling engines swapping around parts to make a good engine out of a hand full of bad ones....but the last rotary I touched was a 84 rx-7 someone abandoned because it wouldn't start. I found something on the carb linkage flipped around causing the problem. My dad drove that little brown turd for years,LOL

If all else fails, I could always drop a V8 in this...but I think a direct replacement engine or rebuild would be cheaper.

When we get it running, he wants to put a stand alone oiler on it...any cons to this mod?

hawcer

I found a parts engine locally for cheap. the front rotor hit the floor causing damage while the guy was taking it apart for a refresh build. he decided to go with a used engine. So with my good front half and the good back half of the other engine. hopefully I'll have enough good hard parts to rebuild it. if not, oh well...it's worth a try. My son will be picking it up this weekend.

Who has the best price on rx-8 refresh kits (seals,springs, apex,orings,etc), Atkins, Goopy, ???

Opinion on reusing rotor side seals? I'll mark what came from where in my engine...I imagine the other engine is in a basket,lol. I'm not against machining/filing/grinding oversized seals for the correct fit either.

hawcer

I rebuilt the engine using everything from the parts engine except the front rotor. All new Apex,side, corner seals, and all springs. The car has been driven now for about 3 weeks without issue.

I finally tore down the old engine to see what happened in the rear rotor chambers. Here ya go....looks like it ate an Apex seal.

hawcer

Pic of rebuilt engine ready to drop back in.

hawcer

I'm gonna post a few tips( not a complete step by step) on doing this repair before I forget all of it.



Pulling the engine:

1. rusted oil line connectors - disconnect both lines on the block(banjo bolts) and move out of the way. The A/C compressor and coils/harness must be removed first to get rear line off.

2. Motor mounts- take the one bolt and one nut off each mount at the frame. jack the engine up enough to relieve weight from the mounts and remove mount "horn" bolts and nuts from the block( easily accessible through the fender well) push the drivers side mount out away from the block, toward the a-arm and leave it there. The pass. mount will be left loose and removed when the engine is halfway out( don't forget to put it back in when going back in with the engine).

3. bell housing bolts- with the motor mounts loose from the engine, allow the engine to drop down. It will hang or sit on the crossmember. This allows more room to reach the upper bell housing bolts. The intake plenum should already be off at this point, or you won't even see the upper bell housing.

4. tranny cooler lines- these can be a pain with the automatic. take all the bolts holding the line brackets out and pull it down and below the oil pan. It's a tight fit around the lower front cover.

5. misc- don't forget to disconnect the upstream O2 sensor ( top of bell housing)and the ground wire that bolts to the intake manifold (near the two covered vacuum ports)



Engine tear down:

1. you will need a torch to heat the front crank bolt, the rear crank nut, and the rear crank hub or they will not come loose.

2. you will need a large socket and breaker bar or the designated long handled tool to remove the rear nut. I lucked out and was given the special tool with the parts engine. You will also need at least a large 2-jaw puller to remove the rear crank hub.

3. I used a couple 4x4 blocks about 2ft long to set the engine on for disassembly. front cover up at first to get the oil pan off and then the front cover, oil pump,chain and gears.

4. now flip it over so the rear housing is up and remove all the block tension bolts.

5. mark and catalog where every little part came from that you plan on reusing...if not sure, mark/tag everything. be careful, the side seals will almost always stick on the iron housing faces when pulling out the rotors.

6. leave the oil control rings/seals and springs (on the rotors) in place until you are ready to replace them. you will most likely be reusing everything except the seals unless damage has taken place. or toss them if you have new.

7. 3. inspect for damage or worn areas. to each their own conclusion here...I'm not getting into it :P


Assembly:

1. clean and decarbon everything. use an old apex seal to scrape the carbon out of the apex seal grooves. Use an old side seal to scrape the carbon out of the side seal channels. ( side seals are tapered, so it will only fit in the groove one way....don't force it)

2. do not clean off the chamber surfaces of the irons or housings with anything abrasive. I used a green roloc bristle disc to clean the seal mating surfaces only.

3. I hand ground my side seals with a sharpening stone to very minimum tolerances. I think specs are .002-.006'. TIP: With your rotors sitting there, you have 6 locations for a side seal to go. When filing to fit, don't just try it in one groove until it is right. test fit in all the grooves. That way you pretty much take care of the longer grooves first and end with the shorter grooves. That way you hopefully won't end up with a "woops, took just a bit too much off" This takes time and patience. you do not want to rush this!

4. use vaseline or tranny assembly goo to hold the corner and side seals and springs in place.

5. Install the Apex seals as follows. With the rotor installed, partially insert the Apex seal with the "helper" end up. guide the small seal spring in first and lower the seal enough to hold the small spring in place. now slip the large spring in behind the small spring and guide it downward. if it sticks, slowly pull the apex seal out until the large spring slides in and stops. Now install the seal's "helper" end. hold it in place and slide the whole assembly down into the groove until it bottoms out. It should be flush with the corner seal. If not, don't force it. double check that the lower corner seal hasn't rotated out of alignment.

6. I prelubed the bearings with lucas oil additive and the chamber surfaces and seals with 2-cycle oil. Don't over do it, just enough for a light coat or the oil will seep into the housing sealing areas...remember, this area won't be tight until the tension bolts are installed.

7. If I remember right, there are at least 3 tension bolts that are longer. just be aware of this...you can tell if it's not in the right hole.

8. I think tension bolt torque spec is 30-35lbs ft.

7. pack the oil pump with vaseline of tranny assembly goo.

Re-installing the Engine:

1. Reverse of what you did to get it out.

2. Be sure to get the torque convertor studs lined up into the flywheel/flexplate.

3. initial startup might require a shot of oil into the chambers. I found the easiest way is to use a squirt bottle through the vacuum hose that comes from the lower intake manifold to the air boot in front of the throttle body. You can also use the two small vacuum ports or pull the spark plugs.

4. don't over rev it and allow time to let things seat in together. It also takes a while for the ECM to relearn idle values. so it may die at first when putting it in gear ot turning on the a/c.

good luck!