Sender: <marv@lancaironline.net> (Marvin Kaye)
To: flyrotary
Date: Thu, 26 Sep 2002 21:03:55 -0400
Message-ID: <redirect-1792054@logan.com>
Reply-To: <13brv3@mchsi.com>
From: <13brv3@mchsi.com>
Subject: RE: [FlyRotary] Re: Synthetic oil?
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What is (are) the weak part(s) that makes an overhaul necessary?

Marko
---------------------

>From what I've read, most 3rd gen RX-7 engines fail from either a broken
apex seal, or coolant o-ring leak. The original owner of mine said that it
had a broken apex seal on the rear rotor.

The apex seals are probably due to detonation.  The twin sequential turbo is
waaaaaay too complicated, and seems to have lots of boost control problems.
There are 70+ vacuum hoses that control boost, emissions, etc, and all this
stuff gets cooked by the temps under the hood. Heat soak temps are as high
as 260 degrees!!!  The car doesn't have the best cool air box, and the
intercooler is fairly inadequate as well.  Between high temps, boost spikes,
and less than superior fuel, there's plenty of opportunity for destruction.

I imagine the coolant o-rings are strictly a temp issue.  The cooling system
is marginal, and Mazda made the water temp gauge non-linear.  It quickly
goes up about 1/3 of the way, and stays there for about the entire normal
operating range of the engine.  When it starts up from there due to a
problem (such as a plastic air separation tank cracking), it's almost too
late already.  Unfortunately, the average owner has no clue how the gauge
works, and will keep driving it until the gauge pegs out.  At that point
they shut it off and let the heat from the turbos and both catalytic
converter finish cooking it.

One other thing that I've suspected is the oil injection.  I believe they
only have the two "dripper" injectors in the housing on these engines, and
no injection in the intake at all.  I have to wonder if that isn't a factor.

A question-  What actually fails if the oil pump stops?  Would the apex seal
break?  Scuff the rotor housing ??  Overheat ???

Cheers,
Rusty