This is my engine rebuild thread. I encourage all constructive inputs and opinions. This is my first rotary engine rebuild and I welcome any extra information from more experienced renesis owners.

Reason for rebuilding.

I experienced major power loss and recurring engine codes(p0420, pending codes: p0301, p0401). The engine could not redline. Power seemed normal at low throttle and low rpm. I tried to de-carb the engine with little to no improvement as well as changed plugs. Originally I thought this was a fuel issue. Possibly the secondary injectors had issues. I ran a conventional compression test resulting in 90 psi on rear rotor and 60 psi on front at approximately 250 rpm. From this I decided a Mazda compression test wouldn't be necessary and the engine had substantial compression loss and required a rebuild.

After pulling the engine I found that the first layer of material in the cat has (what appeared to me) clogged and caved in under the exhaust pressure and the second layer had many clogged sections and damage from loose sections of the first layer.

I broke a vacuum fitting, and the plastic top nipple of the rad... Ops!

Engine came out smooth thanks to DIY thread.

After struggling with the high torque thermal petter bolt, the whole engine has been disassembled, only to find (in my opinion) excessive carbon build up. I also think a corner seal spring was jammed compressed and not supplying pressure to the seal due to carbon build up. Possible cause of lower compression in rotor 1.

I am now in the tedious process of cleaning and planning how I'm going to rebuild the engine.

Current plans
Racing beat street port, omp adaptor, new ignition coils (not oem), cobb ap, cat-less exhaust(may keep factory muffler to keep noise level down), undecided on reusing housings.

My goal is to build the motor reliably, solve the carbon build up problem, pick up a few ponies, gain as much experience as I can ( I have an appreciation of all thing mechanical), with out spending crazy amounts of money. I'm sure I left out tons of details, please ask. Any life experiences with rotary rebuilds are appreciated. I will hopefully have pictures up soon.

 

*facepalm*

you know ur problem is not really a problem right?

what u need were a new cat or test pipe, and a few gallons of water.

oh well

 

I just looked at the stationary gear bearings. One is 2/3s copper so idk if a few gallons of water would have fixed that. Lol. But I do agree with you that removing the carbon(with water?) and a test pipe have would probably returned the car to a more drivable condition. But the engine is out so now is the time to get every thing right. On a plus side rotor bearings look good.

Is it normal for the main bearings to go out and spare the rotor bearings?

 

Not normal I would say but it happens. How many miles were on this engine and what oil was ran in it and was it changed regularly?

 

It was changed ever 5k miles.
5w-20 castrol (I plan on using synthetic thicker oil after rebuild)

04 RX-8 with 90k miles of high rpm driving

 

clearances in this engine require a thicker viscosity than 5w/20. Most of us use 40 wgt oil 10/40--5w/40 etc.
I have used redline 5w/30 with good results so far--it does have a hths factor of many 40 wgts.
Dont break the engine in with synthetic--but you probably already know that.
The oil bypass mod is a good thing to do _ search_ for the diy'er. Lots of good info concerning rebuilding in this forum that doesnt need repeating here.

 

That explains the copper. Definitely use a 30W+ synthetic after the rebuild is done.

 

RX8Club.com - red530's Album: Rebuild

This is a link to some of the pictures I have. (I'm using an iPad when I'm at my parents working on the motor so it is difficult to upload picks and post them)

Thanks olddrager. I was planing on 10w-40. After break in. I'll look into redline, nothing is set in stone yet.

Yeah 9krpmrx8, I was hoping that the Mazda manual would be right about the 20w, but...

I use these forums a lot for info (and to pass time) but I surely haven't read every thing. If there are any threads useful to my situation I would love to know about them. Thanks and I appreciate the support.

 

I used generic Autozone 10W-40 for break in and changed the oil at 500, 1000, and 1500 miles before switching to my normal Mobil1 0W-40. But the brand of the oil is not really super important, just run a 40W or higher and change it regularly. Good Luck!

Edit: Damn that bearing is bad. MAKE SURE YOU MEASURE EVERYTHING! Pineapple racing has some great tools. Do you have the engine workshop manual? If not let me know and I can email it to you.

 

+1. i find its very easy to just go down the list of clearances/specs. it'll pretty much tell you what to replace, and what to reuse. the exception being the rotor housings, you have to go by condition vs budget

 

oh man Synthetic? You guys are going down to hell !

Ok, I use Synthetic, bite me

Anyway, yes, the copper was the result of 5w20, oh lord MAzda knows best we know nothing?

replace both Rotor housing with new (I don't bother with used, thats just me), measure the plates wear, if it's worn, don't bother lapping it, Iron (instead of nitrite) is too soft and you not gonna have a good engine.

 

Housing are concerning me. I have been looking into cermet coating. I can't find too much on the rx8club site, but rx7ers claim it works well. Some have had bad experiences with the company though. Of course the manufactures say it is a miracle, but why wouldn't Mazda do something like this if it is so good? Any other sources of info about this?

 

Don't bother with Ceramic coating, only 1 company can do it properly and it's not cheap. might as well buy a brand new housing.

 

that is true and unless you use ceramic apex seals ( and I wouldnt know why you would want to do that?) use oem seals. There is a lot of misinformation out there.

 

Nycgps, I'm wondering what company you are referring to. Jhb pricing is at 350 a housing. So for two housings plus shipping I would still be well under 1k. It is a little over 700 for just one housing. So if the coating is in fact better than the factory(I'm sceptical), then it would be a no brainer. Jhb claims the use of any seal is ok with the cermet b type coating. I'm just wanting to the history of the engines that have underwent this coating.

Regardless JBH's machinery is broken until summer. They offered me a used cermet A housing, but I would not the interested in only one housing and the price was too high.

Has any one heard of good/bad experiences with this on renesis engines?? Everything I find is rx7 and older. Most are happy with the product but hate dealing with the company(JHB). I still want to know more because it sounds like something I may want to go with on a higher HP build later.

 

Update.
I ran across a used engine out of a wrecked low mileage car. Dropped it in along with omp adapter, cat delete, air injection block off, thermol pellet bypass, new oem coils, plugs, wires, clutch lightweight, flywheel, and counterweight.

The car started up fine other than an extreemly harsh vibration. The vibration is at its worst at 2.5 rpm. It idles and revs normal. I'm getting p0301(misfire rotor 1) and an expexted p2259( secondary air injection system control "b" circuit low).
I installed fresh mounts. Mine were old and worn. This helped slightly, but is obviously not the issue.
Is there any possible way to install the counter weight wrong?

 

Did you reset the NVram (aka brake stomp method) on the ECU? Anytime you install a new engine that is necessary and will almost certainly fix the misfire code if everything is installed correctly. The air pump code could be due to the actuator or the pump itself could be bad or the vacuum hose came off.

 

No, I'm not aware of the NVram. I'm going to do some digging on it. The air blower has been removed thus the p2259. Do you think a miss fire can cause such violent shaking? It really feels like the motor is out of balance. But I don't think it is possible to install the counter weight wrong. Thanks for the input.

 

basically its not possible to install the CW's wrong, however since most CW's look the same from every rotary, its very easy to install the wrong one.

 

There is a DIY on it here somewhere but basically you turn the key to the on position and then tap the brake pedal until you see the needle for the oil pressure gauge sweep back and forth. Then turn it off and then start the car and you should be good to go.

If you deleted the air pump I am assuming you capped it at the header? That code will remain until you block the code VIA the Cobb AP. But that should not affect the way it runs at all.

As for the vibration, well assuming the coils and wires are hooked up and working probably then the other possibility is a faulty engine mount. Or, if you loosened up the power plant frame (should not have had too) and did not properly realign it.

 

Can't be the mounts. I just changed them thinking they where the culprit. And I bought them from the Mazda $tealer$hip(because I was to impatient to order them).

I did remove the cross member under the trans! Would that result in needing to realign the power plant frame??

I do have a cobb to disable codes associated with cat and air injector delete. I'm just focused on getting every thing mechanically sound first.

 

No removing the under brace would not do anything to the power plant frame alignment. Does the engine idle smooth and stable? can you post up an idle log from your Cobb?

 

Last time I hooked up the cobb to the car it wouldn't power up. It works on the computer fine. I haven't messed with it much though. I have been more orientated on one task at a time which is currently getting the car mechanically sound first. I'll hook the cobb up. If it doesn't work I'm going to say a lot of profanity, but I can still post logs from my plx obd device. But I can only record five trends at a time. What would be ideal trends to record if I'm limited to the plx? And I'm not actually driving the car or running it for long periods of time. I don't want to damage anything. Would an idle/ free revving trend be adequate?

 

Yes, the engine idles at a steady 800-850 rpms, it just shakes like crazy! The vibration frequency is in perfect time with the engine and seems to never misses a beat making me think it is something mechanical.

 

Hmmm, just get an idle log of RPM, AFR, STFT, LTFT, and MAFg/s.