Leon Promet wrote:

Hi There,

Seasons greetings to all from the Antipodes!

I'd be having a REAL close look at the dowel land area on the back housing.
 Several probable causes .

1.      Either the housing is cracked where the dowel goes into the rear
housing,  a common problem with poorly tuned turbo engines (they detonate
and crack easily),  especially the early Series 4 ('86-'91) engines.. Mazda
know about this problem and in replacement housings,  the area around the
top rear dowel is considerably beefed up.

2.      A more unlikely source is that you have either pinched the "O" ring that
seals the dowel,  or have left it out all together.  (rare, but it has been
known to happen!)

3.      An even more unlikely cause could be one of the brass oil gallery plugs
is loose.  There's one on the top of the front housing,  (the turbo engines
use this as a turbo oil feed take-off point), and there is another one down
the side of the front housing and a third on the bottom of the rear housing
directly below the oil filter mount supply gallery.  I had one leak just
the other day.  The remedy is to remove the sump,   drill the plug out,
 tap it (!/4 BSP) and plug it with an Allen head plug.  Usually, this
doesn't cause a massive leak like the one in the photo.  Just an annoying
weep!

>From the amount of oil in the pic,  it looks certainly looks like a
pressure leak.  Should be easy to determine if it is the oil pressure
switch.  Just change it or temporarily plug the hole!

An old trick I often use to find that hard to locate oil leak is as
follows:

1.      Clean the engine down thoroughly with degreaser,  wash off and allow to
completely dry.

2.      Disconnect the engine fan to minimise air blowing over the engine.
 (This method might be a problem with an aircraft as you can't easily
disconnect the prop!)

3.      Liberally dust the engine with talcum powder, flour or nikky dust
(that's the stuff panel beaters make when they sand the bog used to fill
panel imperfections when they are too lazy or incompetent to beat the panel
properly!  Wonderful stuff for cleaning up oil spills on the floor as well.
 Better than kitty litter!).

4.      Start the engine and run for a SHORT time (5 - 10 secs).

The oil leak should become immediately obvious.

Hope that this might be of some assistance.

Leon Promet.

Paul Lamar
 
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