Subject: Compression or lack thereof
From: Rotary Engine
Date: 5/14/2011, 6:45 AM
To: AAA Put this in the To box



  I've had my 20B on a test stand all wired up and ready to run for
  months.  But even after endless troubleshooting I haven't been able to
  achieve a successful start.

  Today I hooked up a compression tester and I?ve probably found the
  problem.  Rotors one peaks out at 35 ? 40 psi and leaks down the instant
  I stop cranking the engine, rotor two peaks around 50 psi and leaks
  slowly down, rotor three peaks and will hold about 60 psi.  I didn?t own
  a compression tester when I did the rebuild and figured since I replaced
  practically everything but the rotors and housings I should be OK.



  Any thoughts, comments, or suggestions before I start tearing down the
  engine?



  TIA

  Jay

  Remove the schrader valve from the compression tester and watch it
  while the starter turns the engine over. It should equal pulse 70 to 80
  psi three times in a row on each rotor.

  Sounds like you have one or more stuck
  apex seals. Remove the exhaust manifold and use a small screw driver
  to push on the apex seals through the exhaust port. If you cannot
  feel them move in and out under the influence of the springs you
  have a stuck seal. Spray WD40 in there and keep trying.
  Remove the plugs and put some auto transmission oil in the engine.
  Turn it over a few times and let it sit over night. Then check the
  seals again. Once you get it running it will clean itself up.

  Are you mixing oil with the fuel?

  Paul Lamar


 I have heard a few comments over the years of leftover carbon in the
 apex slots sticking seals after a rebuild.
 Do you recall any issues getting the apex seal springs inserted, that is
 a hint.
 As Paul says, pull the exhaust, check the apex springs for spring.  Try
 ATF in the plugs/exhaust, turn over the engine
 and work the apex seals manually.

 How bad was the edge flaking on the rotor housings you used?
 vendor seals?

 Cheers
 Cary


I also meant to ask about the battery and starter.
A low battery/poor starter will result in low compression even if
everything else is in order.
Sound or video of a start attempt could tell us a lot.
~Cary

That is so true about the starter. Randy Lewis just went through
that exercise. You must really spin that engine.

Paul Lamar

It's been some time since the rebuild so I don't remember with any certainty
details of installing the apex seals. They are OEM parts and I don't recall
any slot flaking.  The starter is a brand new as well as the battery.
If Paul's suggestion doesn't get me going I'll record the engine being
turned over.

Jay

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