How to Avoid Big Air Bubble in the Coolant System was: Water pumpreplacement

[tberk@mindspring.com (T Berk)]

Here's what you need to know about this job:

<really good advise snipped>

- if you purchased a complete water pump your job will be easier. if
not,
  you need to swap the pump in to the old housing. be very careful
with
  the 6-8 bolts between the pump and the housing. They're literally
famous
  for always snapping off.

This part bears repeating. Don't remove the pump via the small bolts
around the outer circumference, instead remove the main bolts holding
the whole unit to the block. 

<more good stuff removed to concentrate on the following>

- when you start the car back up again, keep a very close eye on the
  temperature. chances are you will overheat if you just let it sit
there
  because you will have an air bubble in your cooling system. the
bubble
  sits right next to the thermostat, insulating it and preventing it
from
  opening like it should. 

The 1st thing to do when refilling the coolant system is to pour that
premixed coolant/ distilled water mix (btw- it can be up to 70 water /
30 water depending on conditions), into the motor via the Upper Rad
hose.  

  Some people drill a small hole in the thermostat
  to solve this problem. Others wedge an aspirin inside the thermostat
to
  hold it open until the aspirin dissolves. 

The holes in the face of the thermo was often an OEM thing but I
believe it has been eliminated due to costs of manufacturing concerns.
Long time ago they use to come with a little brass rod stuck in the
hole, it had each end flattened to keep it from coming out but could
rattle around and let air & liquid pass. 

  The 'manual' method of burping
  the air out involves taking the reservoir cap off and running the
engine
  at high rpms until the level in the reservoir drops waaaay down.
Then
  add more water. Sometimes you need several heat and cool cycles too
to
  get all the air out.

  The hub size for the 16v water pump is 30mm.
  Good luck,
  -Toby


Good stuff T., I just wanted to give some thought towards the idea the
motor would get hot enough to pass heat to the thermostat via contact
with the block (vs hot liquid) and this might lead to a shock when the
relatively cool liquid gets passed the thermo and into the hot motor.
Might not crack anything but might lead to gasket creep over time.
Better to allow for the coolant to being as full a contact as possible
during operation.

TBerk