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Wow. I am having SOOOO much fun with this. My question will be in the first response, so you can skip this and then come back to it for references.
OK - here's the story. And it's long story, so grab a beer or two. Bought an '04 Automatic with low compression on the front rotor. The engine in it was one of those 'imported from Japan with low miles' jobbies. Previous owner (PO) also gave me his old engine/trans for parts if I needed. I ordered the Atkins 04-11 Rx8 Basic Engine Closing Kit with standard Atkins options, along with the 04-08 Rx8 4-Port Automatic Engine Gasket Kit (N3Z1-10-S50B). Also got the Sohn adapter and bottle kit. I inspected the eccentric shaft and bearings, and all were within spec. I opted not to do any lapping of the irons, as it has been debated pretty heavily here. Cleaned up the rotors, checked the apex channels, all seemed ok. The side seals from Atkins are not pre-cut, you gotta grind down one side to get them to fit.
To remove the engine I used a hoist, rather than pulling the engine/trans/subframe as a unit. Not too hard, 4 nuts on the torque-converter and 6 trans bolts.
Also - I sent the housings out to GOOPY to have them refinished, as there were some chatter marks and some flaking right at the end of the exhaust cycle portion. Needless to say, the flaking was still there when they came back, but all the rest looked GREAT. ON WITH THE BUILD!
The build went fairly smooth, lots of instruction here and videos online to follow - side seal to corner seal clearances are good, apex seal clearance in the rotor is good, plenty of grease and assembly lube throughout. I decided to use the older front iron, because the PO hacked part of the engine mount stud off. I can only assume he was having trouble getting it in, likely using the same method I used. Also, he said the original motor failed at the rear rotor, so I assumed the front was fine.
Putting the motor back in went ok, but when I was putting the plastic intake manifold on I dropped the bolt from the back side. I looked and looked, but I couldn't find it anywhere. It sounded like it went right down the intake. (I SHOULD HAVE REALIZED THIS WAS IMPOSSIBLE IF THE BOLT HOLES WERE LINED UP). Rather than immediately pulling the motor, I tried to go in with a flexible magnet stick through the intake, No bolt found. Assuming it went all the way in, I used that same magnet stick through the leading spark plug hole (the big one). I heard the familiar TICK, indicating the magnet found its target, and I VERY GENTLY removed the magnet stick. It came out, but the magnet that was embedded in it did not. (NOOOOOoooooooo!)
Needless to say, removal is now necessary. Of course, during the removal process I found my bolt wedged right between the intake and the housing. It never went in, just got stuck in a hard to reach spot.
I only needed to partially disassemble the motor, as the issue was with the rear rotor only. I loosened the bolt and nut at BOTH sides of the shaft, in case I needed some 'wiggle room'. For you kids at home, don't do this if you're not going past the rear housing for reasons we will get into later. I got my magnet out, reassembled, and got everything back in place. The engine was really hard to start at first, but eventually caught and turned over. It didn't idle well at all, and it would immediately die if I tried to put it in gear.
I checked the compression using a piston-engine compression tester with the Schrader valve removed, and filming with a slow-motion camera. 90-95 PSI across the board on the rear rotor, but only 65-70 on the front. SOMETHING is wrong, back to the drawing board.
During the second tear-down, I found out why it was initially so hard to turn over. Remember that 'wiggle room' I spoke of earlier? Well, one of the thrust bearings (those round needle bearings) had slipped in between the spacer ring when I moved the shaft ever so slightly. i was crushed and locked in place. ALSO, I noticed there was a deep groove at the ignition cycle portion of the front iron, as if the corner seal had been popping out right there and digging in. Good thing I had that extra motor, because I now needed a new thrust plate and ring spacer. Also, lucky it didn't damage the shaft, just those two parts. I bought a new 93-11 Rx7 & Rx8 Thrust Bearing Set (N3F1-11-D54) from Atkins and used the thrust plate and spacer from the old motor. I wasn't going to use ANY bearing parts from a failed motor, besides, they're too cheap to have that be your point of failure down the road.
Using a blowtorch, I was able to loosen and remove the engine mount stud from the beat front iron, and I used the same method to get the hacked one from the newer iron. THIS TIME I opted to do the manual lapping method I saw either in this forum or in an RX7 forum. Everything looked OK and, IMO, I didn't have any deep grooves.
Hoping the "third time's a charm" theory would apply here, I reassembled everything. After installing the engine and getting everything hooked up, I tried to fire it up. It WILL NOT start.
After repeated attempts and fully draining my battery and charge-pak, I pulled the spark plugs to get compression readings. The plugs were wet with fuel, so I'm clearly getting gas. Compression test still shows similar readings as before, but only slightly higher on the front rotor. I guess that groove was affecting something. So, if it's similar to what I had earlier, why won't it fire up at all?
I devised a method to check the spark plugs firing at the correct time, building off the method I used to check compression. I had some old plugs, so I put an old plug in the trailing plug hole and put my compression tester in the leading hole. I wrapped bare copper wire around the bases of all the plugs and grounded them to the frame I connected the leads to the plugs, separating them into two pairs. I then filmed the action in slo-mo video. Every time the front housing showed compression, the front plugs lit up. Also, the rear plugs lit up at an exact opposite interval as the front.
My assumption is I'm getting fuel, compression, and spark-at-the-right-time.
My question is - can anyone give me some tricks to try to get this fired up, or some guidance as to why I'm not getting the compression I should? Front iron looked ok, any chance I'm losing something through the rotor - is that even a thing? I'm very frustrated.
I'm willing to do this a fourth time. I'm in Bangor, PA - Near Allentown - and I have beers for anyone willing to come over.
For anyone wondering what I meant by 'flaking at the very end of the exhaust cycle', here are 2 pictures I took to send to Goopy BEFORE I mailed them the housings. This is only the worst one, and this one ended up being used on the rear where I'm getting OK compression. As you can see, it's right at the end of the exhaust stroke, and I was told of all the places to get this, this spot is the least harmful.
Again, this is the worst one of the two, the other was not as far in as this.
Pretty sure the rear plugs aren't used when starting... so if they're lighting off I would question the timing. Especially if they're lighting up out of phase, that sounds like a trailing that thinks he's a leading for the other rotor.
That flake won't affect your compression reading but it's not awesome. The way you tell it, the big parts are barely passing muster for a reliable rebuild.
Are you getting fuel in the right timing? It's easy to mix up the injector plugs.
Pretty sure the rear plugs aren't used when starting... so if they're lighting off I would question the timing. Especially if they're lighting up out of phase, that sounds like a trailing that thinks he's a leading for the other rotor.
That flake won't affect your compression reading but it's not awesome. The way you tell it, the big parts are barely passing muster for a reliable rebuild.
Are you getting fuel in the right timing? It's easy to mix up the injector plugs.
Hmm. That sort of tracks. Initially when I was checking the spark plugs, only the L plugs would fire for the first 3 pulses. Only after the first 5 pulses did the T plugs fire. Here's the slo mo of the plugs.
Sorry for the low lighting, slo mo video is hard for me.
As far as all the 'big parts' passing muster, not sure what you mean. As I said, I checked the clearance of the apex seals in the rotor channels, and it was good. Resurfaced the housings, calipered the bearings and shaft to be sure there was no excess slop. It's just not firing. I'm using spray starter fluid to try to force the thing to go, it's just not.
Also, here's the compression I'm getting. The front rotor, even though it has all new seals is still pretty crappy. Unless I'm mistaken, though, I should still be able to get it to fire, right?
Woo-hoo! So, one of the things I replaced was to 60-amp fuse for the smog pump. During one of my startup attempts, I saw smoke coming from the smog pump, and when I felt it, it was hot as hell. I disconnected the smog pump and it fired up. Hopefully I can take it from here.
That's weird. Was the smoke exhaust or was the pump burning itself out? The pump is only active in the first 30 seconds of operation or so, so the only way I can see it getting hot fast is by regurgitating exhaust somehow... But it should be feeding air into the exhaust, not consuming exhaust gas....
Yeah - one of the things the PO mentioned was that the smog pump made a 'jet engine sound', I assume it was always running. I'm guessing it burned itself out. As I said, it finally started and I let it run for a bit, hoping it might smooth out any rough spots and and eventually make a good seal on that front rotor.
I'm assuming anyone with any experience at all knows what happened. For those that do not posses this knowledge, NOTHING happened.
So, does anyone have a good source for rotor housings? I'm searching and finding nothing less that $950 for a new one, and I'm hoping to spend a bit less. I'm not cheap, I'm poor. Also, is it possible I'm losing compression through the rotor somewhere? As I stated, I have the 'basic engine closing kit' from Atkins, which included apex seals and springs, side seals and springs, corner seals and springs, and rotor O-rings. All that crap is still new. The side seals were 'cut to fit', and I'm fairly sure I got them right. One side was angled already. I used a knife sharpening stone and cut them at an angle, then used a feeler gauge to check the clearance to the corner seals.
The rotor seems fine, no cracks or holes. I'm just not too keen on doing this build again with a new housing, only to have the same issue.
Another question, since I'm going in again - I checked the I.D. of the rotor bearings against he O.D. of the eccentric shaft, and all seemed O.K. I was using those spring-type telescopic tee-gauges to check the I.D., then measuring with a micrometer. Same mic used on the shaft. I realize using those tee-gauges can give erroneous readings, only the slightest misalignment can give you a false measurement, but the bearings show no sign of degradation, still all silvery inside (no copper).
How hard is it to replace the rotor bearing? Atkins sells a tool on their site that looks like it will prevent deformation ( https://www.atkinsrotary.com/store/T...ol-ARE902.html ), and I have a giant C-clamp that will fit to the center of the rotor. I'm just wondering how smoothly it goes in, do I need to heat it up, should I just stick with the ones I have, etc.? Is this something I'm better off actually using a hydraulic press, or has anyone tried to crank one in with a clamp?
And is it possible I'm losing compression through the rotor somewhere? Has anyone ever heard of this? This is my first experience with a rotary, but I REALLY AM awesome....
Ok, I think I messed up, but I want a second opinion. I replaced some side seals this time, because I noticed some were out of spec. I replaced them initially, but the first spec I found for side seal to corner seal clearance was a maximum. When I trimmed them down (ATKINS sends them with only one side trimmed and you gotta trim the flat side so it comes to spec), I trimmed them too much. I was able to move some around and get within spec, but 3 just HAD to be replaced. For the new ones, I trimmed them to MINIMUM SPEC.
Here's my question - if I made them TOO TIGHT, could that make them bind against the corner seal when they warm up, therefore making it hard for the apex seal to move freely in it's groove and cause a loss of compression when warm?
I wish I had the knowledge to help my friend.
Maybe if you send a pm at Kevin from Rotary Resurrection?
Have you asked Atkins directly? Maybe they have some solid advice?
07-23-2021, 09:52 AM
