Mailing List flyrotary@lancaironline.net Message #14860
From: Leon <peon@pacific.net.au>
Subject: Corrosion in New Engines
Date: Thu, 6 Jan 2005 08:27:52 +1100
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Hi Guys,
 
Whenever I split a brand new "out of the box" Mazda engine,  there is always residual water/coolant inside.,  and with it,  a little surface corrosion.  See pix.  This is an FD REW 13B.
 
Mazda test run all their engines and then drain them.  Unfortunately,  you can't get ALL the water out,  so the bit that's left just festers and putrifies.  Fortunately,  they use glycol/corrosion inhibitor,  so whatever corrosion does occur in minimal.
 
For long term storage,  the best solution (pun intended) is to flush the cooling system out with first fresh water until all traces of coolant are gone, fill to overflowing with warn soapy water (made by dissolving a cake of soap overnight in water).  DON'T use liquid soap (NOT the same as cake soap) and under NO circumstances EVER use detergent (it's REALLY corrosive).  MUST be ordinary cake soap.  Get all the leftovers from the bathroom and just dissolve them.
 
If you use cake soap,  the soap will coat everything with a protective layer of Sodium Stearate and/or Palmitate.  This is a simple housekeeper's trick to stop steel wool from going rusty (in the days before stainless steel scrub buds).  About a year ago,  we had the unfortunate experience of having to repair a really nice PP engine that had sat about for nearly 10 years.  All nicely mothballed inside with oil.  The rotors and seals were perfect.  Unfortunately,  the rotor housings were all rotted out.  It took 2 days to repair them with Devcon (Epoxy stuff like JB Weld).

So,  to summarise,  yes Cyril,  your factory engine was test run by Mazda,  and yes,  Cecilia,  they do leave a bit of water in the galleries,  and yes Clifton,  it does tend to leave some surface corrosion..
 
Cheers,
 
Leon
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