Here are the essentials.

                  --
                  Paul Lamar ...No rotor no motor.


              Paul,
              How would you purge air out of the system in this
         arrangement?  I know
              that this has been discussed in detail in the past, but it
         seems that
              you would need a line from the rear side housing to the
         pressure can in
              order to purge air that may be trapped in the engine.

              Mark S.

              You must run a vent line from the highest point in the system
              to the top of the pressure can. In a tractor tail dragger it
         would be
              the rear (car) end housing. The housing closest to the PSRU.
              The best place is where you have the pressure fitting now.
     I think
              it is the return line from the water heater port in the stock
              RX7 system.

              The pressure container must be mounted as high as possible.
              The cooling system is constantly generating tiny steam
              bubbles. These must be able to rise to the highest point in
     the
              system which should be just below the pressure cap. When the
         pressure
              in the system rises to the blow off setting of the pressure cap
              this steam accumulation will be the first thing purged to
     the catch
              can.

              Paul Lamar ...No rotor no motor.

         Paul,
         Yes, wp-plumbing5.jpg shows it more clearly.  I didn't see that
     line in
         the previous jpg.

         On my installation, the radiator is angled from front (highest)
     to rear
         (lowest), so I have a 1/4" line going from the upper most tank
     back to
         the pressure/swirl tank.

         One caveat, when filling the cooling system, it is possible
     (likely) to
         get an air pocket in the vicinity of the wp impeller.  In my
         installation (20B, thermostats removed), running the engine will
         not purge the air from this area.  You must remove a plug from
     the side
         of the wp housing and continue adding coolant until liquid runs
     out the
         hole.  Then replace the plug, run engine and coolant should
     circulate.
         An easy way to tell if it is circulating is to hold your hand on the
         outlet from the wp after the engine has been running for a
     minute or
         two.  If it is warm/hot, water is circulating.  If it is still cold,
         there is no circulation.  It is my understanding that more than one
         engine, following rebuild, has been fried due to this
     scenario.  It may
         not be a bad idea to install a petcock on the side of the wp housing
         for
         the purpose of purging air when refilling the cooling system.

         Mark S.


     Instead of reinstalling a plug in the side of the wp housing, would it
     be worthwhile to run a purge line from there to a high point in the
     system?  I guess it might depend on how tough the plug is to get to once
     everything is installed on the engine..


     Matt-

     Here are some water pump pictures. Perhaps Mark S can mark
     them up using MS paint for us. The 13B Cosmo pump and the 3 rotor
     pump are the same. Note the bleed hole at the top of the
     pump cavity.

     Paul



Paul,
Here's a picture of my water pump housing.  There's a plug in the side
that I now use for a pressure sensor.  I remove the pressure sensor when
refilling the cooling system.  I add coolant until it starts coming out
the plug hole, then I replace the sensor and continue filling.  My wp
housing does not have the bleed hole as shown in
Bulents_Cosmo_pump2.jpg.  Did it come that way or did he add that?

I've resisted adding a purge line as it is an additional failure
point.  A petcock or Schrader valve would be preferrable.

Mark S.


I don't recall Bulents pump having that feature.
Bulent's pump had the bleed hole as stock.

What did you do about the bypass?

I see you are using the Wiggins couplings. Nice work!

------------------------------------------

That looks like the highest point in the system.
Where is your pressure container and pressure cap?
If it is above this point which it should be you
should not need this tap.