garyc

My name is Gary C. and I restore old cars and motorcycles for a gentleman's personal collection here in Oklahoma City, Oklahoma. This week the gentleman I work for purchased a 2005 Mazda RX8. This car isn't for his collection, he just likes the RX8 and wanted one to run around town with. When I do a restoration project I usually join a forum based on that particular car or motorcycle. It has always been a priceless help obtaining info from those who know their stuff, in this case the RX8.
The RX8 we bought this week has a bad engine. The rear chamber has no compression. When I pulled the trailing spark plug on the rear set I also discovered bits of thin hard metal that I assume is part of one of the apex seals. It has to come apart.
So if any of you engine experts ever read any of the Newbe threads I will be asking a few questions during this build and would appreciate your input. As far as my abilities, I was a motorcycle technician for over 30 years and have been doing this restoration gig for the last 5 years. I have never worked on a rotary except for one time I did a quick make run job on a Suzuki RE5. I cleaned the carb. slapped it on the butt and away it went.
The car I am posting about is a 2005 RX8 with a normally aspirated 4 port engine with an automatic transmission. It is showing 145,000.0 miles.
I see that this site limits me to 30 days before I can go on to the regular forum. In 30 days I will be done with this project and will be surfing some other forum for info. Thanks in advance for any input.

Ber1n

Here's a few things to get started for pulling the engine. Hopefully, they prove useful since both examples work with a MT Rx-8.

This is from a re builder that uses these forums, RotaryRessurection. All credit goes to him.
It's a PDF of a Thread he made here:

http://static.ibsrv.net/rx8club/RENE...%20REMOVAL.pdf

Here's a YouTube video of pulling an Rx-8s engine also:

Lastly, this rebuild was done on an RX-7, but I think video series will help you understand the inner workings of a Rotary Engine. It's incredibly useful.



It's pretty easy .

garyc

So my first question is, what places have the best prices on quality parts. I wont know exactly what I need till I get it apart. I do know that I will need to replace all the seals and components related to a normal rebuild. I have located some of this stuff but am open to suggestions. Chances are pretty good that I may need a rear rotor and the housing because of the metal I found in the spark plug hole. So any suggestions on these hard parts or services for repair please chime in. Also I will be documenting this and posting photos for future engine builds. Thanks Gary C.

garyc

Thank you Ber1n for the quick response. I will look through that info in the morning. I plan on pulling the engine tomorrow evening and will post some photos. Thanks again Gary C.

Ber1n

Parts are pretty expensive for Rotaries. For seals and gaskets, Atkins Rotary has decent prices for good quality parts. Although, I don't participate in the rotary community very much, so I don't know much about Rotary parts suppliers overall. Everything I've needed for my car, I bought from reputable sellers on E-Bay.

garyc

I disassembled the engine and after researching the parts I decided to go with a JDM engine. I was looking at $1200.00 for the rebuild kit, $1400.00 for a rotor, and another $800.00 for the rotor housing. I bought a complete JDM engine w/ transmission and all the components $1800.00 delivered. Plug and play?? I understand that I have to use the U.S. ecm (specific to this car) because of the anti-theft.
Also, another note. The cat has been gutted, how will that affect the fuel mixture based on data from the o2's to the ecm? The JDM engine has the connectors for both o2 sensors. Any In put will be great. Thanks Gary C.

ShellDude

iTrader: (12)

I'm assuming you bought another 4 port motor and 4 speed auto transmission. It's a drop in replacement if so. You'll want to use your existing ECU, even if the new motor came with its own.

If not then you're going to need a few more items.

It sounds like you found an eBay motor. They normally run (when the seller states as much) but the quality of the motor is hit or miss.

I got a very similar deal on a 6 port motor and 6 speed manual transmission. The motor, while it would run, had major carbon build up, the throttle body was bad and the clutch was shot.

I paid to have it rebuilt with Atkins cryogenic seals prior to running it.

You sure your friend wants an auto? The 4 port Renesis only makes about 3/4 the power of a 6 port and the auto paddles get old quick.

Williard

iTrader: (18)

^^^Listen to Shell.

That's all I have to say.

Travis

garyc

Thanks for your response. Yes I got the 4 port, 4 speed automatic with all the components. The only thing I plan on reusing is the a/c compressor. I left the original compressor and hoses intact. The engine itself is very clean externally which doesn't mean a lot. I know it's a crap shoot but I was looking at over twice the money or more to fix what is there. The gentleman I work for is 72 years old and isn't an aggressive driver so it doesn't have to be fast. We gave $1600.00 for it and other then the engine the car is immaculate. I will have to remind him every time he drives it how to warm it up, drive it like you stole it, then how to shut it down and to get it to full operating temp. every time he drives it. Also Can a person use a bore scope and view through the leading spark plug hole to see any excessive carbon build up? Or is the build up or wear evidence of the build up where it can't be seen in the chamber? I was a motorcycle tech for over 30 years and know a lot about piston engines. But have no experience with a rotary except a Suzuki RE5 about 30 years ago. Thanks again.

ShellDude

iTrader: (12)

You can get an idea of the condition of the housings and rotors with a scope, definitely. The exhaust ports should be telling too.

You might want to pull the SSV and clean it. There are a few other things you could do proactively if you have the time.

He'll enjoy it I'm sure, and best of luck on the swap!

garyc

The SSV will be easy to check out before I install it. I will have to get a hold of my buddy with the scope in the morning. That will be better done with the engine out so I'll wait till tomorrow night to start putting it back together, Thanks for all the input. I'll post the final results and some pics when it's done.

garyc

I posted on Youtube this video of doing a compression test on the JDM engine I bought through eBay. Please understand that I am well aware that this is not the correct way to do this in that I don' have the correct tester and really don't have time to go find one. What this test tells me is that I have a consistent compression of each chamber by watching the fluctuations. They are consistent at 100p.s.i. per fluctuation and there are no fluctuations exceedingly higher or lower then the 100 p.s.i. reading. The readings are consistent from front to rear. I understand that 100 p.s.i. is not the best it could be and it is not the worst. I also know this test should be done at operating or near operating temperature something I can't do with the engine out of the car. If need be I will test it again after the installation.
If this was a public business everything done here would be fully brought to the customers attention and the customer would be making the sole decision on proceeding with the install or rebuilding this or the original engine. Since this Is a private shop and just another toy for my friends vast collection of cars and motorcycles we're putting this engine in as it sets. If it works, great, if it don't we'll do it again. But next time it will probably get a BBC v8 or at least a SBC v8. Thanks for looking I'll keep you posted.

garyc

I finished the engine install about 5:00 this morning and fired it up. It ran smooth but billowed smoke for several minutes. I let it come up to operating temp. and topped off the coolant and transmission fluids. Today I took it for a drive would get a battery light. Went back to the shop the light went out. Went for another drive and started having transmission shifting problems like a limp mode, lost steering etc. all voltage loss related. Got back to the shop and am testing the charging system now.

garyc

I found the problem with the charging system. I had 2 loose connections at the under hood fuse panel. My dusk to dawn adventure the other day had taken its toll, I did not tighten the posts for the two leads from battery to the fuse panel. Man these things sure go crazy when that voltage drops. First was the battery light followed by the no elec. steering warning then the transmission limp mode warning (nothing past 2nd. gear). Not to mention that it wouldn't start after a drive to the store. I tightened the loose connection and charged the battery. Now it works like it should.
I read briefly some of the forums about the starter and battery problems and have an idea for you that will give you more then enough boost at start up. You can take 6 350 farad 2.7volt super capacitors and a simple circuit board configuration and give your starter a brief burst that will spin the engine over like a sewing machine. The entire device is less then 12" long, less then 4" wide, and 3" tall and will fit in the cavity right in front of the windshield washer bottle. The 6 capacitors are tied together in series making their voltage capacity 16.2 volts. They will never charge beyond the voltage that your alternator puts out. Then you tie in the capacitor bank to your battery parallel (pos. to pos. neg. to neg.) As long as you don't dead short the circuit, it will not have any effect on any of your elec. system except at start up. Then it will pull that stored energy to the starting circuit and spin over a weak compression engine enough to start it. The whole set up can be done for less then $100.00.
Here are a couple pictures to show that I'm done and to show that I'm not blowin' smoke . Thanks everyone for the help. Gary C.

Williard

iTrader: (18)

Have you done a hot compression test yet?


Travis

garyc

Hi Travis.No I have been too busy on another project.I'm in the middle of building a '34 Ford Sedan. I drove the car a little bit and have had a few issues. The gentleman I work for took it out this morning and called me after a bit and couldn't start it. I took my super capacitor jump box and it fired right up. The problem he told me was it would start but not rev. I got it back to the shop and scanned it and had a code on the MAF sensor. I cleared the codes and tried to start it and all it would do is barley idle and not rev. It showed another code for the MAF sensor again. I removed the MAF sensor and checked it for any blockage or debris. It was clean. I reseated it and the connector and also found a small diameter hose loose under the plenum assy. (the one with the little check valve in it). I cleared the codes fired it up it bogged (lean reaction) a few seconds then cleared up. I took it for a 10 mile in traffic drive to a friends and shut it off. Got back in it and it fired right up. Drove back to the shop on the highway and run the **** out of it . it showed another code so I scanned it and it shows a rich fuel mixture at bank 1. I assume that is because of the gutted cat.??? Then only thing I noticed is that at steady throttle in 4th. gear (automatic) at 65 m.p.h. it had a very slight surge. I ordered a super capacitor kit today and will put on it as insurance for my boss. I do need to check the compression hot and am sure that it is a little low but it starts fine for me after a long hot drive. Thanks Gary C.

garyc

I just now (04/20/2015, 7:55pm cst) went to move it into the paint shop here. It had set about an hour after my 15 mile highway drive. It started right up but I noticed a blubber (rich fuel mixture) below 2500 r.p.m. but that cleared up after a couple 3500 r.p.m. revs. I pulled it into the building and was going to do the shut down procedure and noticed a bog at 2000 r.p.m. So, I know it will be rich after a hot or warm start up then clean right out but now it seems to go lean after it cleans out. ??? Any input? Thanks Gary C.

ShellDude

iTrader: (12)

How are you measuring mixture?

garyc

I'm not measuring the mixture, I don't have access to a co2 scanner. I am simply stating that on a hot start up the car has a rich mixture then cleans out after a couple revs. Then it goes too lean as if I have an intake leak or low fuel pressure. At 65 m.p.h. on the highway I have a slight surge that could be rich or lean or just a reaction from the oil injection. It is a very small surge and most people wouldnt even notice it.

Sukhi900

Hi, im new to this forum and i was just wondering what would be better me getting my engine rebuilt or should i buy a used one in good condition? My engine recently lost compression and now i gotta decide what would be the better option and cheaper to do.

garyc

I am no expert on the rotary engines, but I do have over 30 years in the motorcycle service industry. Buying any used engine rotary or piston is a crap shoot. Roll the dice and hope for the best. On this project I had to do one or the other. The engine in this car had a bad rotor and one bad rotor housing. I was looking at $3600.00 in parts alone. Because I had very little time for this project I opted to purchase a JDM engine from a vender on eBay. It was $1800.00 with free shipping. JDM engines are advertised to have less then 50,000.0 miles on them and they are engines that come out of cars from Japan. The one I got has decent compression but not ideal and I am still ironing out a couple issues to get this car dependable. Right now I am having a fuel delivery issue.
If this is a car you plan on owning awhile I would have your engine rebuilt by a competent/ rotary expertise shop. So you have to figure out how much you have to spend. Buy a used engine you might get a good one or you might get one that is no better than what you have. I can't quote you an avg. of the cost for a rebuild, but it will fall into about the $2500.00 to $6000.00 price range. JDM engines usually have the transmission, alternator, starter, a/c comp., and engine harness.
Thanks Gary C.

04Green

iTrader: (1)

@ Gary, well said...

Um, fuel pump on these cars fails early...

and, it is easy to get the injector cables in wrong.

9krpmrx8

iTrader: (46)

They don't fail early, that is just something that is blown out of proportion on this site. I have replaced quite few for people over the years and the pumps that I have seen fail typically are close ten years old and high mileage. Most get replaced when people are trying to diagnose by parts replacement rather than actually troubleshooting the problem. My original pump was working just fine when replaced for a BHR unit at 120,000 miles or so when I went turbo and I have seen plenty of 100,000 + mile units in addition to mine.

Sukhi900

Thanks for letting me know, i think ill just get a rebuild by a rotary shop rather than dealing with a dud motor, i was actually thinking of selling my rx8 when this happened but im a fan of rotaries now and there just really fun to drive haha.

linuxadickt

garyc, be sure to join the local group. lots of good info and help.
have a rotary compression tester and some other rotary specific tools

https://www.facebook.com/groups/OKRotary/