Strange ?corrosion? on rotor
08-28-14, 12:29 PM
#1
Strange ?corrosion? on rotor
Finished cleaning up this rotor and found this damaged area. It looks like pitting that spread into the apex seal groove. None of the seals on this rotor were damaged, this was just happily hanging out underneath.
I have two questions and please don't slay me on this one: Would this be usable? The rotor is perfect everywhere else and the corrosion is not visible in any form. I understand this would weaken the rotor at a critical location, but the motor is not going to be built for high boost.
Lastly, has anyone seen this before? Is this a common occurrence? It seems to me that this would be a very difficult place for any corrosion to take hold.
I have two questions and please don't slay me on this one: Would this be usable? The rotor is perfect everywhere else and the corrosion is not visible in any form. I understand this would weaken the rotor at a critical location, but the motor is not going to be built for high boost.
Lastly, has anyone seen this before? Is this a common occurrence? It seems to me that this would be a very difficult place for any corrosion to take hold.
08-28-14, 01:30 PM
#4
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if that doesn't go through to oil, and the grooves are in spec, it should be ok. that area sees oil on one side and gas/oil/carbon on the other, so it doesn't usually rust...
08-28-14, 05:03 PM
#6
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I'm betting it's void in the material from the casting process. As said before, it's ok if it doesn't go through to oil. The one lower right (first pic) looks like a wear spot from the wire type corner seal spring.
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08-29-14, 12:29 PM
#12
It was very dirty on the outside. This is my first rotary rebuild, so I don't have a trained eye for what is usable and what isn't, but it doesn't seem too terrible.
Coolant seals were intact, the rotors had a lot of carbon on them but none of the seals seemed to be stuck or anything. It was leaking a lot of oil from the front cover/oil pan/omp. The housings are my main concern, as they are showing a bit of chrome wear on the edges.
Coolant seals were intact, the rotors had a lot of carbon on them but none of the seals seemed to be stuck or anything. It was leaking a lot of oil from the front cover/oil pan/omp. The housings are my main concern, as they are showing a bit of chrome wear on the edges.
08-29-14, 07:08 PM
#15
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that one looks pretty nice, the water jackets on yours are really clean, usually they are all pitted and rusty.
the wear on the rotor housing is by design, they made the triangle of the apex seal smaller so it seals better, but then it also wears the housing right there
the wear on the rotor housing is by design, they made the triangle of the apex seal smaller so it seals better, but then it also wears the housing right there
09-01-14, 01:41 AM
#17
Here are photos of the internals with minimal cleaning done so that I can check the dimensions. Just wanted to give everyone a look at a turbo motor with 110k on it as well as get a second opinion on some of the wear.
Starting with the rear iron, there is minimal step wear and warpage within limits. I feel that it is usable.
Rear rotor housing: This one was giving me 82psi and I think it was either the apex seals or the groove cut into this housing. It is only a couple of thousandths (in) deep and it is showing some chrome flaking near the exhaust side. I don't know if I should chance using it or not.
Center iron has not been measured at this time but looks good.
Front housing: This one has chrome wearing in multiple places but primarily near exhaust side there are a couple smaller areas around the housing that I am concerned about, maybe someone with some experience can chime in.
Front iron has not yet been measured but looks fine.
What would you use/replace? I know it is difficult to tell in the photos but I did the best I could with this camera. I also understand that new parts are always going to be better, I just fear that I may let a very minor issue prompt replacement of something that may not need it. This is my first rotary build so any input would be greatly appreciated!
Starting with the rear iron, there is minimal step wear and warpage within limits. I feel that it is usable.
Rear rotor housing: This one was giving me 82psi and I think it was either the apex seals or the groove cut into this housing. It is only a couple of thousandths (in) deep and it is showing some chrome flaking near the exhaust side. I don't know if I should chance using it or not.
Center iron has not been measured at this time but looks good.
Front housing: This one has chrome wearing in multiple places but primarily near exhaust side there are a couple smaller areas around the housing that I am concerned about, maybe someone with some experience can chime in.
Front iron has not yet been measured but looks fine.
What would you use/replace? I know it is difficult to tell in the photos but I did the best I could with this camera. I also understand that new parts are always going to be better, I just fear that I may let a very minor issue prompt replacement of something that may not need it. This is my first rotary build so any input would be greatly appreciated!
09-02-14, 08:00 AM
#21
MECP Certified Installer
That corner seal wear looks kind of deep for 110k miles. I tore my engine apart at 162k (original engine that came with car) and it didn't look that bad. PO did not premix.
Maybe it's just the pics though.
Maybe it's just the pics though.
09-02-14, 10:46 AM
#23
so i thought something looked funny...the motor when its on the stand is inverted from what i would have expected. granted you are doing a teardown so it doesnt really matter.
when doing a rebuild theres a torrington bearing that needs to stay put and can slip if the motor is rotated over before its all final torqued. theres some good videos online of 13b rebuilds. one in particular is 2 parts and about an hour long total. it goes over filing the side seals, how NOT to install a corner seal when test fitting etc. its really good. you should grab a beer and watch it.
also look at mazdatrix website about that torrington bearing. they have some good info of what happens when things go wrong and how to prevent it during a build. Aaron cake also has some info on it (i think).
when doing a rebuild theres a torrington bearing that needs to stay put and can slip if the motor is rotated over before its all final torqued. theres some good videos online of 13b rebuilds. one in particular is 2 parts and about an hour long total. it goes over filing the side seals, how NOT to install a corner seal when test fitting etc. its really good. you should grab a beer and watch it.
also look at mazdatrix website about that torrington bearing. they have some good info of what happens when things go wrong and how to prevent it during a build. Aaron cake also has some info on it (i think).
09-02-14, 11:56 AM
#24
MECP Certified Installer
My car when i first bought it, The OMP worked for about 100 miles before it took a dump. It didnt take out the ECU so for that reason I know it went into 50% duty cycle failure mode. I replaced it very quickly and the engine ran normal, but it was drastically worn out. Right before I replaced the engine it was 85-80-80 on the rear and 65-60-60 on the front. On the front iron I had not one coolant seal crack but THREE, all mostly on bottom exhaust side. 3 cracks there is very rare.
New engine tested at 120 on all faces of both rotors.
Even after 162k on the original factory motor, and even with its low compression, The rotor housings where just barely out of spec when it comes to side seal wear. When I say barely I mean BARELY, but I went ahead and chose to get brand new housings and not risk it. By the way, brand new housings are god awful expensive.
