RotaryResurrection

iTrader: (3)

Right...I know about the letters and sizes. I was kinda hoping they were hand fitting them like the older rotaries required. I think the factory clearance is too sloppy to suit me. The rotors are getting 200k miles worth of carbon buildup under the seals in just a few thousand miles based on the cores I have torn down (about 8 now).



IF the core is already in your facility for teardown and inspection for possible reuse, why do you need to know it's current compression anyway?

How strict are they being about part reuse versus replacement? I have seen many a mazda reman from rx-7s that had questionable parts inside them.


It is to my understanding that mazda will not let an individual deal with their reman program directly, you have to go through a dealer and do core exchange...you cannot have your core rebuilt, and you cannot specify that you want an "all new parts" reman versus a "some new parts, some used parts" reman, even though they do exist.

EdwardsB

^the standard piston tester...wasn't aware there were special ones for rotaries. Learn something new everyday. yeah 1000 is not cheap by any means.

RotaryResurrection

iTrader: (3)

You didnt read any of that big long post I wrote out above, did you?

Sleepy-z

Yeah I heard they used to fit the side seals from some of the techline workers, I wondered why, my guess is its faster to get the motors built this way or something in japan. And yeah the public cant actually deal with us direct, you can always purchase one retail if it came down to it.

As for why we are doing the compression test again, its mostly for the possiblity that the dealers are just assuming the motors are bad and trying to turn in a profit for themselves. Sometimes there compression number look made up. I dont know if thats the exact reason but thats my guess. Dealerships make a lot of money off warranty jobs in the end and its not a bad idea until you get caught.
But the last reason behind it is the japan engineers want the actial compression #'s and more then half the dealers dont send the #'s in like they are suppose to.

EdwardsB

Wow, I have no idea how I missed that . Thanks for redirecting me there and posting all that information, good read!

We all have our times of stupidity.

RotaryResurrection

iTrader: (3)

Well, I am sure it is faster and thus cheaper.

BUT...I also think it is sloppier work. I am not saying it doesnt work okay, it does...but I think hand clearancing is always best.

Whether or not you know it, the rotors are not symmetrical from face to face, side to side. because they are a cast part that is finish machined afterwards, and not an actual CNC/machined part from the beginning. This is why they can't just make one size of side seal that fits all of them...the length of each side seal slot is different.

What they have done is devised a way to measure that slot length and mark it, and have a seal that is 'close enough" that fits into it. This still leaves for a very loose clearance though, as opposed to custom fitting longer seals one by one into each slot. This is how the old rotaries were all done.

I am used to building rotaries with 2-6 thou, maybe 8 max, of side seal clearance. And you guys are building them with 14 to 24 thou. The gap at the end of the seal lets compression leak past, and also lets carbon leak past too. This is why the sides of the rotors between side seals and the scraper ring are black on the renny cores I am tearing down with 10-60k miles, while older engines could keep this area clean for about 80-100k miles at least. Honestly I am surprised these engines make as much static compression as they do with that amount of seal gap.



It was to my understanding that in order to be cleared for warranty replacement, the tech first ran the vacuum test, and if those results were borderline or low, then the comp test and then called the results into MANA hqtrs and would then be given the yes or no for replacement. One would think it a simple matter of tagging the offending core motor before it leaves the dealership so that the comp numbers accompany it to your facility.

But I know what you mean about them not doing it right...I get work all the time from people who were told they needed an engine, and it turns out that it was just flooded or something else simple (not rx8s). And I also get work from people who were told they needed a coil pack, TPS, or a fuel injector, and they actually do need a motor, so it can go either way.