Brede

I'm in middle of my first ever rebuild and have come up
with a few questions..
The engine failed to the usual o-ring failure, burnt inner
o-ring between the front rotor housing and front side
housing. As far as I can understand this is because of
engine overheating, and warpage of the side housing (thus
bringing the seals in direct contact with the combustion
process).
But I just can't seem to find any warped internals!
1. Can the o-rings fail without warpage of the side housing?
2. Should I replace the side housing anyway?
3. I've got some chrome flaking in the rear housing, but it's
only like 1/16" wide and 1" in length. Can I reuse this
housing with success?
4. Will my engine behave differently with my new OEM Apex
seals?
5. Do all of the internals really have to shine like gold
before I reassemble the engine? The important part is
to clean the seal grooves real good, isn't it?

RonKMiller

Greetings from the states...

1. Yes, it can also be caused by failure due to corrosion of the coolant
passages. As you have noticed they are pretty thin in this area.
Look at it carefully to make sure there is no pitting where it leaked.

2. You probably don't need to, but you do need to take a straight-
edge to it and dial gauage to make sure it is within specs
in the Mazda manual. Since you are reusing the old rotors
this should not be an issue. Just make sure you replace
all the old components in the same positions you took them out.

3. This is always a judgement call on the part of the rebuilder.
some flaking is always present and not neccessarily anything to
be concerned with, BUT, the best rebuilds always use new rotor
housings. Since you are using new apex seals I would absolutely
use new housings so that they seat correctly. It's asking too much
to expect new seals to bed into old housings and produce a good seal.
I know they are expensive but you really don't want to go through all
this trouble and and have low compression forever. While you are
at it use new bearings as well.

4. You should have higher compression numbers, but other than that, no.

5. You have to be absolutely meticulous to clean everything, and more
importantly clearance everything as well as set the end play correctly
or you will end up with a piece of junk. Make sure you clean the end
threads of all the bolts when you put it back together and put a
drop of oil on them. Tighten them gradually and in the correct
sequence before you take a torque wrench to them for the final
tightening. You are trying to build a level "sandwich" so that
everything seats with equal loading on all the surfaces.

6. Break it in slowly with no boost for at least the first 500 miles.
Then do an oil and filter change and vary the rpm for the next 500
miles with no boost. Run it at 4,000 for 30 seconds on flat ground,
then 3500, then 6,000 for 30 seconds, and so on. This creates the
pressure you need to seat everything without high loading forces.
Then just drive it normally for a few days, then repeat the above.
By the time you are at 1,000 you should be good to go for some
boost. Change the oil when it starts to change color instead of
some arbitrary mileage or time. Use dino juice, 10W30 in the winter
and straight 30W in the summer. It will never break in with
synthetics. It will take a good 5,000 miles for a full break in.

Good luck!