Mailing List flyrotary@lancaironline.net Message #29807
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Mazda Engine
Date: Mon, 30 Jan 2006 09:39:11 -0500
To: <triptrish@durango.net>
Cc: Rotary motors in aircraft <flyrotary@lancaironline.net>
Hi Don,
 
Your question concerning a used 13B was posted to the Fly Rotary list.
 
In addition to what you have already been told, here are some things to consider .
 
1.  Get both the injector sets, the injector fuel rails and the intake manifold if possible.
 
2.  Get both the leading and trailing edge ignition modules (usually mounted on the fenders or firewall).  They are each over $500 if you order new from Mazda.  Even if you intend to switch to a different ignition system (such as the LS1), its worth getting the Mazda units.  I would also suggest getting the alternator while you are at it.  Again, you may want to replace it with a lighter unit later, but for now it  will serve.
 
3.  Make certain the engine has a crank angle sensor (looks like and goes into the hole that a distributor would).
 
4.  Make certain the flywheel (flex plate on automatic) is still attached to the flywheel end of engine - that way you can be fairly certain that the matching counterweight is still there.
 
5.  Check the iron housings (on each side of aluminum rotor housings) for any signs of overheating such a bluing, burnt oil, etc. 
 
6.  Give it the "whump" test as described by others if you can't get a compression check.  If you have access to a Mazda compression checker that is great, but most don't so you can use a regular compression gauge.  When turning the engine over you should see 3 flickers as each of the 3 faces of each rotor complete a revolution - its hard to read but the needle should bounce above 80 psi for each.  If a apex seal is gone you will only get one good bounce as the seal between two of the faces is compromised and you'll get poor compression (if any) on those two faces.
 
7.  Check the oil dip stick to see if the oil appears/smells burnt (overheated).
 
8.  If you have access to the exhaust ports, you can actually look up into the ports and see the apex seals as they come around.  You can also stick a bronze/brass rod up and gentle push on the apex seals, they should slide in and out of their grooves approx 1/16-18".  If the engine has not been run for awhile, the carbon can set an freeze the seals.  Also, if you see anything other than a light tan color around the exhaust - it could mean internal problems - especially indications of oil or coolant leaks. 
 
 
9.  With 137K miles, I doubt that the rotor housings are in great shape (but, they might be).  The side housings may be in need of surfacing.  But, you should be able to reuse the eccentric shaft, the stuff under the front cover (crank angle sensor, oil pump, water pump).
 
10.  If its free - forget all the above - take it!  Even if total useless (unlikely) it will be something you can tear down, use as a template for fitting to your airframe, etc.
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
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