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cooling system air bubbles - fix



> I drilled a 3/32" hole in my thermostat in that part that looked like it
> opened (the large disc shaped piece, not the spring-loaded small one at
> the other end)..

the large disc that sticks out never fully seats against anything
internally, so drilling in it is useless. you need to drill 2 holes in the
disc that is normally closed (i.e. the tstat also contains its seat). this
disc seat is also the same part of the tstat that mates with the water pump
housing and the tstat cover o-ring mates against. i find it easier to drill
the 2 holes in this plate itself, only about 3/8" in from its edge to ensure
the hole doesnt mess up the sealing surface it provides when installed.

with the holes drilled in the correct place, you can fill the system quickly
and completely via the reservoir, with the engine off. you can then start
it, rev a few times, keep rpm at about 2-3k, and you should see coolant
spraying from the upper rad hose air bleed line (one that goes into the top
of the reservoir, near the cap). steady coolant stream from that line
indicates the system is full of water. you dont even have to run it up to
temp. without the drilled holes, you have to let the engine get hot, opening
the tstat, sending a huge slug of air into the reservoir. i have also found
that the coolant level doesnt go up and down while reving either.

> I hate vw cooling systems..

me too, especially since the head to aux pipe hose turned to mush on my
yesterday and i spent all day today looking for a replacement. luckily i had
another one in a box in the shed (knew that junk wouild come in handy).

> -Toby

hth
Al