Dave told me the other day not too many people have seen inside a high mileage rx-8 engine.. Here is one with a little over 100k. Rebuild quality is a lot higher quality than the remans we have seen. One thing we are noticing is these motors move around a lot more than the rx-7 engines. There is a photo attached of the rotor housings wearing into the side irons. Premix seams like a must on these engines...

 

Thanks for posting! So Bearing wear was an issue in this motor too. Do you have any HONEST service history on the car? oil type, OIC's, etc.

 

Any history on this motor?

 

Wow - look at that side seal clearance.. And the none existent apex height. I wonder what teh compression numbers were.

 

Very interesting - sometimes the premix, non premix, oil, temperatures, coolant, engine blowing up etc. discussion just makes me tired. There must be tons of RX-8 owners out there not on this site driving their cars without any idea about this stuff - what in the world are they doing? It would be very interesting to actually get some solid statistics on engine failure rates for each year car. Sometimes I can't tell if we're all too paranoid on here, or if the Renesis really IS that bad that 100,000 is like a golden crown - if you can make it there, you're special (which is sorta sad and it stinks if it's true).

Nevertheless, I really enjoy that car.

P.S. Thanks for posting - it IS helpful to see the inside and we'd all definitely be curious of the fuel/premix/oil habits

 

This owner isn't on the site. I think it would probably be shocking to see how many people are having engine failures. We just had another call, another blown engine.

I don't have any more info to share to so far, I am going to look into some more background. I know its been a single owner, younger fellow. Mods are an intake and exhaust.

Most Rx-7s exhibit the same type of bearing wear, and all of the rx-8 engines I have seen have it too.

The apex seals are completely toast, I haven't seen apex seals wear this bad in a long time. The housings need to be replaced too.

 

you aren't kidding, those seals have nothing left. I kinda wondered how the rx8 seals would hold up considering they are so much shorter than the rx7 ones.

 

seems more like a collapsed apex spring... engine is actually not that bad for 100,000 miles, looks like a no compression rotor, I cant believe the other rotor is the same or that engine would not start.

sideseal clearance that nemesis8 mentioned...just wow that is bad. THAT would render that engine very difficult to start and very low power.

sideseal clearance is always overlooked by newb rebuilders

 

I have to learn this stuff.

 

Well looking at the apex seal, the rx8 corner seals have those metal inserts compared to the rubber ones on the rx7's. the metal inserts seem to hold up the apex seal, which is which is what allows them to use the shorter seal. In this case, it is resting on the insert, I would expect to see some more height off of the apex seal than what I am seeing.

The collapsed spring theory could be right tho. Ive only torn down one renesis, so I am not used to seeing the shorter seals alot.

You are dead right about the side seal clearance. Isnt the stock clearance supposed to be between 0.002 and 0.003? That seems like a hell of alot more than that!!!

 

Are you saying that is a rebuilt motor with 100K?

 

I misworded that sentence. This is not a rebuild. It is a factory original. I will post another photo to show the apex seal wear.

 

e shaft movement?
Would that bearing wear cause any kind of wobble in the shaft?

dont know if pre mix would stop that seal wear or not?
rotors not balanced well enough?
thanks for posting dudes.
olddragger

 

Let's say the apex seals didn't fail, how long would bearing wear like that last before things got real ugly.

 

Yes, more more pics. I love the engine pr0n!

 

Showing my age here, but I've see bearings in worse shape out of (piston) motors. The wear was so bad that the engine oil pressure light would come on cause it was flowing so much out of the gaps. First the light would come on at idle, then in low rpm cruising, then you'd start getting rattling noises on startup. Eventually, the bearings would get so loose that one would spin and seize the engine. Then you'd pull it apart, get the crank reground and order oversize bearings from JC Whitney to fit. With leaded gas and crappy straight-weight oil, getting much past 100k miles from a standard Detroit car of the 60's was a matter of luck.

 

Wow did you bring back some memories I thought were gone ....then to add JC Whitney ...those catalogs and returning parts over and over........Thanks.

 

I remember those days myself! + Busted blocks from freezing temps especially the old flathead fords.
But you have to admit the old engines were not turning 9K rpms nor having a seals(rings) crossing the ports!
OD

 

I took some more pics for you guys. By "movement" I'm referring to symptoms/clues we have noticed on a few engines. The wear marks in the iron picture of my first post are just a taste of said symptoms. The picture doesn't do it justice (probably due to my lack of photography skills) but it's a sign that the rotor housing was working a groove of it's own into the side iron. This 'groove' or wear pattern is not common with the older 13B's and we are further investigating if more 'movement' of the engine components is due to the higher allowed rpm of the Renesis. We have offered a stud kit for some time for the older 13B's and it seems more and more that they are needed just as badly on the Renesis engines.

Obvious copper showing on a bearing is not catastrophic until the bearing clearance in that specific area has become extreme. Generally this is not the case. The real issue is how long has the bearing been over stressed in that specific area, or how long did it take for the bearing to 'wear out.' The bottom line is that if the bearing did not look like it does now since the last oil change, there is a real problem. If the wear was gradual than I would say you 'got your money's worth' (for lack of a cliche.) Again I would like to re-hash that all we know right now on the history is that it is the original engine and has just over 100k miles.

On to the pics... This engine's water jacket looked very clean for the claimed miles it has on it. The pic of the front cover coolant passages are cleaner than most we've seen, although there is some decent oil tarnish around the engine oil exposed areas. (This front cover picture was taken after an initial cleaning.) I have included a picture of the obvious wear on the apex seals, the extreme carbon caked rotor, and what it looks like after an initial clean....

I might take a few more pictures if anyone is interested and if we discover anything interesting enough to share...

 

Your first pictures are decently sized, but these new ones are much smaller... can you upload bigger ones?

Secondly, you talk about the water jacket groove wearing itself into the iron, and this is not like older rotaries. Which older rotaries are we talking about here? As you probably know rotary engines from 86-2002 had the water jacket groove on the side iron, and not the rotor housing like the renesis. You would want to compare to a 12A or a pre 1986 13B.

Lastly, any clue as to what brand of oil the owner ran? Was it Pennzoil?

 

Turblown, do you run a shop or out of your house kinda deal?

 

trouble is we are seeing that kind of bearing wear on a 50K engine.
100K ok, but 50K-- WTH?
Intersting on the movement. May need tightening from time to time?
I have always said ---no no to a 9K redline. Centrifical force increases to where it is 1.7 times stronger at 9K versus 7K just for an example. I am surpercharged now and I can have a 7.5 rpm redline.
Great info dude.
OD

 

Sorry I have already gotten rid of the pictures I posted. I could take some more if time allows. The older rotaries I was referring to were any of the 13B's or 12A's we have seen. I see your point about comparing apples to apples. We have no idea on the oil brand.

We work out of a full size shop with a few lifts, small machine shop, ect. We are located in Peoria, AZ.

No problem. Yeah, the more we disassemble engines the more we notice the bearing wear issue and others that seem to be renesis specific. We have a few tricks up our sleeves we might make available soon.

 

Hey thanks so much for taking the time to contribute. I for one, really appreciate it. Any further input is greatly welcomed.

 

subscribed ... greatly anticipating further discussion....