fong

iTrader: (77)

hi, not sure anyone notice that bruce in his rebuild video says that is important to ensure all parts go back to where they are from, when we reuse some parts. for example, side seal, oil seal spring, corner seal spring, corner seal, etc.
he even draw pictures to mark down which is which.

my question is: why that is important? he didn't explain that in the video. is it ok to mix them at long as they are in good reuse condition?

thanks

Aviator 902S

When an engine is broken in, the components wear themselves into position--- in the exact location that they were originally installed.
But if they are mixed on re-assembly they are no longer broken and may no longer have have the proper running clearances that they had prior to the teardown.
If, for example, you mix up the side seals, the end clearances may no longer be sufficient to allow for expansion due to temperature variation.
If you install an oil seal spring backwards or with a locator peg not into position, the spring will "walk" out of position. You'll be tearing this engine down again before you know it.

I'm guessing that you've inadvertently mixed up your components. If so, all is not lost.
You'll need to first place all of your seals into the rotors with the worn sides facing outward. Then use a feeler guage to check end clearances between the side seals and corner seals. (Bruce's video will state the proper clearances, as well as the correct way to install all seals and springs). If there are discrepancies in the clearances you'll need to use the trial and error method switching the seals around until the clearances are within stated tolerances.
As long as they are, and as long as all springs are installed in the proper direction the engine will run fine. But since you probably will not have every piece in the exact slot that it used to be in there will probably be a longer break-in period.

ERAUMAZDA

The reasoning for this is that engine parts do not wear evenly. Everything that happens in side of an engine is an uncontrollable enviroment. Every compenent wears slightly different and when you mix up parts they can cause a large or small variation in the end....

Results:
Compression values change
Oil pressure values change
Tempature changes
Vibration changes

Example: Rotors are a match set. You don't want to use a front A type rotor with a type B rotor. The mix matching of parts will cause more vibration

In reality.....the variations will not be so critical...however it is good practice to put them back were you pulled them from.

fong

iTrader: (77)

thanks a lot. I have to admit that I made a silly mistake when I took the seals out. basic on my understanding to your comments, are these true?

1)the springs are ok to mix up. but side seals and corner seal are the ones need to check clearances. can I do that after I clean up the rotors or before the carbon remove.

2)apex seals are ok to mix up, and reuse, as long as they are within the spec range.

3)what about those metal O rings?

thanks

Aviator 902S

Clean and remove carbon from all components prior to measuring them. The side seal springs are a standard length so if they're mixed, no problem.

Apex seals may appear to be within specs when held side-by side, but they also wear along the flats--- ie: the sides of the seals which come in contact with the sides of the slots on the rotor. This wear is easier to see under a magnifying glass and appears as a "scalloped" wear patttern along the length. Since the engine is already apart, I'd replace the apex seals as a matter of course, they're not that expensive for the stock ones.
If you have to replace any side seals though, keep in mind that they must be ground down slightly on the ends in order to attain the proper clearance from the corner seals. This is a trial-and-error procedure.Mazda intentionally supplies them a few thousandths of an inch longer than required to allow fine-tuning the clearance. Be careful not to grind off too much.

As for the metal o-ring housings, as long as they're clean and undamaged go ahead and re-use, but be sure to replace the neoprene o-rings inside them, and be sure they're installed correctly with the springs in the proper orientation as per the video.

1adzam

Aviator's explanation is right on the money. I have been told that reusing Apex seals is like putting old rings back in a piston engine rebuild. They are the heart of what provides zoom-zoom. One thing on the oil control rings.... if they are out of tolerance (20,000th of an inch on the wear line) they should be replaced. They are expensive but the o-rings won't be able to seal if the rings themselves are worn.