Check this out - cracked corner seals
 

So about 6 weeks ago I lost my motor, after going back and forth on rebuild options I decided to take the time off from work and rebuild it. I found some very interesting things upon tear down and I was wondering what your opinion might be as to how these things happened.

Motor background:
04' with 110K on the clock, has run 5w-30 Royal Purple and Idemitsu premix since 38K. It was driven hard on occasion but it was mainly a DD with mostly highway mileage.

All of the corner seals on the rear rotor's front face were cracked.

The front iron looks like it tried to port itself but I'm curious as to how.

The front rotor is beyond beyond repair one of the apex seals was completely gone and there was no trace of it at all but the little piece of that apex seal was still there. The other apex seals are there but they are a part of the rotor now. That rotor also had these marks on the front face.

The side seals were in good shape but the springs had disintegrated (I have to say that those pieces are INCREDIBLY sharp), there was basically no spring tension on the seals.

Here is a pic of the front stationary gear bearing - All the bearings looked fine for the mileage on the motor. I was expecting them to be heavily worn given what others have experienced with the higher mileage motors.

Thoughts??

looks like something was seriously eating away at the housing wall -- pic #2... guess we know where your seals went!

Looks like it lost an apex seal in the front rotor and as it went for a ride it did alot of damage to the rotor and port on the face of the front iron.

I would bet that when the front rotor blew it put extra pressure on the corner seals of the front of the rear rotor. Here is how I would guess it affected it: I would suspect that the apex seal floating around and getting lodged cause the shaft to flex a little putting the pressure on the rear rotor and breaking the corner seals.

I have been wrong before.

The only way to crack the corner seals on stock ports is w/ pressure outside of combustion pressure.

Good luck rebuilding it.

No, no, no.

Your supposed to put a title up like "5w30 DOES CUT IT. Pics of good bearings after 100k!"

And then sit back and watch 50 pages of carnage.

:lol: :)

anybody want to talk about the side seal springs?
How the heck does apex seal get pass a side seal?
from what I can see is--not much carbon buildup at all?
Thanks for sharing this OP.
Little more history?
Redline limit--temps--??

Rotary Inspired -

That makes sense, but on a totally stock motor? The rotor housing was scratched up quite a bit but the plates themselves weren't at all.


LOL, well I was contemplating posting them in the synthetic oil thread, bring the popcorn!



I'm confused as well OD, I was thinking that those marks on the side of the rotor are from that piece of the side plate but it's on all three faces. I was expecting those plates to be ruined from what I've heard about the renesis when a seal fails. There were NO scratches, or marks of any kind on them. The apex seal appears to have disintegrated, there was a fine powder in the exhaust port. Might be a question of what came first.....the seal failure or the side plate failure.

Yea, the carbon that was there came off very very easy. The rear rotor had more but it wasn't built up badly. The exhaust ports had a good deal of carbon buildup though.

Redline was stock @ 9000, quite a few times it went to the fuel cut off @ 9500

Temps - It saw from -10 to 110F, and I used 5w30 the entire time. Sometimes I would let it warm up, but most of the time I would start it and wait until the rpm would drop down and then drive off (30 seconds max). Oil was changed ~3000


Any other questions, or if you want to see more pics just lemme know as I took quite a few.

more rotory porn please

Interesting. Any mods? Any overheating incidents? Any milky oil problems? What was the amount of premix added? What do you think your average commute leg was? Oil consumption?

While the 5w-30 seems okay for the bearings, it seems in this case the 65k of pre-mix didn't help the seal wear.

Here ya go:

1st is the rear iron
2nd is the carbon buildup in the exhaust port
3rd is the front rotor front face
4th is the middle iron front face
5th is the eccentric shaft


I have more on the camera but it will have to wait till later when I can get the usb cable.

No mods to the motor other then reliability ones....BHR Fuel pump and ignition...

No overheating that I'm aware of, though this past summer it did get hot enough for the temp gauge to move and I know that it's not the most accurate thing in the world.

Only the normal milk on the dipstick in cold weather.

It varied from no less then 4oz up to 8oz per tank. For the past 2 years I have been adding 8oz per tank.

The average commute varied over the years. It was anywhere from 3 miles up to 45, but has been at 45 one way for the past 2 1/2 years. Those 3 mile commutes the car barely even got warm by the time I was where I needed to be.

Oil consumption was about a quart every 3000 miles. It remained roughly steady the entire life of the motor.

oh man that exhaust port is pretty nasty. all of them like that?
OD

Subscribing. There are tons of marks on your rotor faces and side housings. Ouch. It's unfortunate to see the premix didn't help your apex seals. :(

This makes me want to strip my motor apart and see whats going on. I see there isn't much that is salvageable. I would like to know what ate away at your rotors like that. That carbon build up is pretty intense as well, did you ever seafoam the vehicle?

OD - Yes they are

Shaun - That pic of the rear iron I like because it shows the wear patterns very well, but they really aren't that badly worn.

Doc - The rear and center plates are reusable, they have around .002" of wear on them which makes them a little more then halfway through their usable life. The rear rotor is also usable. I would like to know as well, there were no pieces of the damage causing agents left so I don't really know.

I was under the impression that the stock apex seals don't disintegrate when they fail, looking at the dead rotor it really looks like something hit the apex seal making it bend over into the rotor and caused it to fail, the next apex seal in line was cracked but remained in it's groove, the third was hit by shrapnel but didn't crack. They are however permanently jammed in their grooves. Looking at the damage done I'm kind of leaning towards the plate having a failure. I'd really like to hear opinions on that.

I'll get pics up of the damage to the rotor and housing in a little bit.

Okay here's some more pics of the ruined rotor and that rotor housing. Yes those scratches are as deep as they look.

Also the third pic is of the rear housing, wanted to show that there were no cracks at the spark plug holes.

Yikes, thanks for sharing. I'd like for the experienced builders to chime in.

dude--i really think--on seeing that rotor face--that a seal didnt do that.
Plate failure makes more sense to me?
That would somewhat answer the side seal spring mystery also?
Which came 1st seal or plate--dont know.
No cracks around the spark plug hole--lots of seal skip going on--you liked rpms?
OD

^ What do you think it's going to look like with a whole metal apex seal running around loose in there?

;)

wow i can't believe that it's scratched up so badly!!

hopefully you can figure out what caused.

Yes I do OD :) it sounds so glorious.

The apex seals were worn more in the middle, which I don't get since I was premixing....makes me wonder if 8oz isn't enough??

I am glad I am doing 1oz per gallon, hopefully it helps.

dan--that is a large amount of bad gashes? Plus he couldnt find any of his apex seal that broke off and the 2 parts off his plate had to go somewhere?
I have never seen one that scarred. Yall have probably seen more than I have so tell me --would one apex seal cause that much damage that fast?
Why did the side seal springs disintegrate like that?
OD

well if thats the case the question would be did the apex seal wear down, or did the apex seal split a piece off. If the apex seal had a piece break off then MAYBE its feasable, but I would think this was something else because the seal could have found the path of least resistance. Speaking of which.

Did you have a cat on the vehicle? have you checked inside the exhaust for any more pieces of the engine?

Then you haven't looked around enough! lol

When my last motor came apart from a bad front stationary gear bearing, the front rotor was practically round instead of triangular.

Smart ass POM...

this coming from an Englishman who does not even OWN an RX-8...HOW Dare you!:rant:

Denny, thought the same, sort off.

Some say Mazda's "sloppy" side seals are moving too much when cold and cutting through the Side Seal Spring (S), Mazda have modified side Seal Springs in 2009, but left the Side Seals as they are.

Yeah, I would like to know more about engine history..

Well 5W30 WONT CUT IT...:eek:

Seriously, starting Pre-Mixing at 38K is too late, yes I know you got to 100K, But think about it, if the middle of the Apex Seal was wearing unevenly because of the lack of Lube in the middle after 38K, the damage is done (well some), by adding pre-mix it is not going to correct or straighten a slightly concaved Apex Seal is it.

WOW how long did you drive it for, the damage on the rotor/housing is pretty bad.
Must of ran like a piece of crap, starting?, or did it just die on you??..

What are you going to do, buy new parts, strip another engine for parts??
Or have you though of buying a Mazmart engine from Paul??

They do beautiful Rebuilds and at a good price, and are great honorable Vendors you can trust....

WHERE is Paul when you need him??..

Good luck and thanks for the pics..

Thems the whitest gloves I've seen for a while ....

Doc - Yes the car has a cat, and there is nothing solid in there....just fine powder.

Ash - What would you like to know about the history? Oil was changed round about every 3000 miles, coolant every 30,000 or 1 year.

The car was driven about a half mile after it died. It restarted after sitting for about 15 minutes and had to be held at 1500rpm just to stay running.

I'm with you on the seal wear

Thanks :)

Had to prepare for my photo shoot ;)

They keep having engine problems, what'd I want one of those for :naughty:

Besides, I can't afford 7 litres of treacle every time the engine wants servicing :SHOCKED:

I heard molasses is good an cheap in UK, particularly for those glorified "Beach Buggies" :eek:

It's not doing too bad for a beach buggy, it's towed 4 people out of hedges/ditches today in the snow already...'specially with this torqueless engine ;)
20w-50 would look like molasses here at the minute anyway, -12*c this morning

subscribing. I have more to add, but it will be later.

Hince my statement that others have seen more than me.
I do know I drove for around 100miles on one rotor after breaking an apex seal on the race track and my rotor didnt look ANYTHING like that?
Regardless the plate stuff had to go somewhere and thats where the powder came from?
I wonder if plate failure took out the seal?

Man that looks as bad as my cousins face when he was 14 yrs old.

Ash thanks about the side seal info.
OD

OK here is my take on it.

You had an apex seal fail on the front rotor. The reason it failed I can only speculate over the computer, but history repeats it's self so I have a pretty good idea.

As the apex seal wears it gets smaller, and the rx8 seals are already much smaller new than previous 13B seals. As it wears it is less stable in the apex seal slot at high rpms and begins to chatter. At this point it the seal could have damaged itself during the chatter or actually left the apex seal slot during high rpm use due to the wear. Take your pick neither are good.

This happened more often than you would realize w/ the 89-91 rx7 N/A motors. Before you dismiss this read on. In 89 Mazda raised the redline from7K to 8k, lightened the rotors, increased compression, and changed the intake manifold design. Sound familiar? Now I have seen several of these motors loose an apex seal at 4K and up in the rpm range on stock 3 piece seals as they wear and get over 60K miles. The 3 piece seals will actually loose the top piece as it wears and will flip out of the groove or break.

All the damage you see in your motor is a direct result of the apex seal leaving its home. When it does this in the Renesis it does not have the easy exit through the periphial exhaust ports of the past 13b's. The seal has to try and get to the side exhaust port to escape the motor. Unfortunately this design creates a disaster when the seal fails. Your seal looks to have bounced around on the side of the rotor between it and the front side plate causing the damage to the rotor. The scoring on the side plate came from the damaged rotor and seals running on that plate before shutting the engine off. From there it looks like the seal started to shatter into little bits and traveled around the combustion chamber several times damaging your rotor housing and the faces of your rotor before being crushed enough (your fine dust) to exit the side exhaust ports.

This process above put extra pressure on the front face of the rear rotor cracking the corner seals. I have tried to run a motor on broken or cracked corner seals and the compression is so poor its hard to keep the car running let alone getting it to start.

That's my take on your situation. Hope it helps and good luck w/ the build.

While there is a quite a bit of carbon in the exhaust ports, but its not overwhelmingly more than what I have seen. I would guess that the BHR fuel pump supplies more fuel than the stock pump richening the mixture some, which in turn adds carbon.

Excess fuel is what creates the carbon. The oil injected in the chamber is so small that it really does not have much play in this. You should see the carbon build up on the JDM turbo motors. Quite impressive to say the least.

Rotary Inspired - Thank you, I won't discount anyone's opinion on what happened as it all will help put the pieces together on what happened.

The apex seal that's missing looks like it broke and bent over into the rotor as there is a depression about a 1/2 inch long. Besides that the front plate has that missing piece and only 1 scratch in between the intake and exhaust ports. The only thing left of that apex seal was the corner piece.

How do you feel the apex seal got in between the side seal and the plate?

What do you think about the side seal springs? Given what you said about the extra forces cracking the corner seals, I am thinking that they might have also destroyed the springs.

:biggthump The only other way I have seen to accomplish this is w/ boost and lots of it.

The apex seal got between the plate and rotor as it was trying to exit through the exhaust port first time around. It did not succeed in it's endevor and went for a ride getting trapped as the rotor crossed over the exhaust port. Then the rotor carried it up to the intake ports where it got jammed up and took out part of the intake ports. From there it just went round and round throughout the motor til it was small enough to exit stage left.

That's my take on the situation. Good luck.

Less than 2% at high rpm in my (turbo) application ....
In normal low load operation ,no difference .

That's definitely not an oil related failure.

So basically the bearings look good so using a good synthetic and changing it often seemed to have helped. I just wonder if he had been running the SOHN and premixing since day one would have helped.

I would suspect that lack of lubrication to the center of the apex seals is what ultimately led to the death of this motor. That apex seal died first, and on it's attempt out the exhaust port damaged the side and corner seals.

here is an option ..http://www.goopyperformance.com/content/corner-seals

who be this member since 2007 with only one post???

lol that is funny. whats not funny is a website/company charging $75 for a file, feeler gauge, and a SS brush:SHOCKED:

Goopy? That was the best name available? All I had to see on their site was the claim that their oversized tension bolts were a better alternative to dowel pinning. Um, actually no it's not. Those won't really do anything to strengthen the engine at all as dowel pins are limiting movement in an entirely different plane. I wouldn't use anything from a company that claims that. Keep in mind using studs would be better than using bolts anyways so if you were going to replace the bolts with something stronger, use studs and not larger bolts. That's a waste of time.

*If* the housings can take the extra clamping loads from the larger bolts without distortion, they would do much the same.

But that's a big if....

Now I am convinced of synthetic at 3k intervals - except I will go to 3,333 miles so my engine will die at 99,900 miles!

Did you ever have your oil tested? I had rotella 10W30 tested at 3k and it's viscosity was down to5W20. So, I was convinced that wasn't going work.