Miata Mailing List: May 1999, Message #255

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roger meadows wrote:
> 
> this weekend i plan on draining the radiator on my '92.
> 
> there appears to be a drain plug that can be accessed thru the plastic
> cowling directly underneath the radiator.  is this the correct plug?
> 
> in any event.....what is a good procedure for draining/flushing?
> also,,,,any recommendations on the brand/type of antifreeze?

My procedure (others may vary):

* Place heater control to "hot" position.
* Place drain pan under drain plug (you found the correct plug).
* Remove drain plug; gravity takes over.
* Remove radiator cap to hasten drain.
* While waiting, suck coolant from overflow reservoir.  A turkey
  baster will work, or just remove the reservoir and dump it.
* When finished draining, replace plug.
* Fill radiator with water.
* Start engine, turn on heater.
* When engine is hot and heater putting out heat, shut down engine.
* Drain coolant again. (Careful - it's hot!)
* Replace drain plug.
* Add about 1/2 gallon of Prestone antifreeze to radiator.  (I live
  in Florida - depending on your location, you may want more or less
  to prevent freezing or promote better cooling.)
* Fill remainder of radiator with water and replace cap.
* Fill coolant overflow reservoir with water.  (Later on the road,
  some will probably overflow - that's okay.)
* Run engine with heater on "hot" until engine reaches operating temp.
* Update your computer maintenance log.

You don't want to have too rich an antifreeze mixture, because
antifreeze is not a good heat-exchange agent, and your engine could
overheat.

I'm a fan of MTL products, but I don't use MTL's Water Wetter, because
several on the List have reported accumulations of "brownish gunk" in
the cooling system after adding it.  The root cause may or may not be
Water Wetter, but since I haven't needed a wetting agent to keep the
cooling system working well, I don't use it.

Good luck.

--
Bill Gusky and Petunia
Red '91, license "MOMENTS"
http://www.totcon.com/users/moments
DeLand, Florida
"Too soon oldt, und too late schmart!"