12valve V6 T-stat replacement

[Todd Young]

The dealer will tell you that you have to pull the timing belt to
replace the T-stat, well I didn't.
Here's the process I went through to chance the T-stat on my car, a 90
series, without changine the timing belt.
==============
Changing the T-stat is an exercise in patience. First you have to remove
the plastic engine covers,
both the top and front covers. The front cover is held in place with two
allen head bolts. Once you
have the covers off, the next step is to loosen the power steering
pulley bolts, there are three of
them, all allen head bolts again. Just loosen them, don't remove them
yet. Now you will need to
remove the serpentine belt. I think my car has the older tensioner, I
used a 10mm allen wrench to
slacken the idler pully, then remove the serp belt from one pulley. Then
pull it out completely. I
seem to remember that once a serpentine belt has been run, it should
always run the same direction,
so either mark the belt, or toss it and get a new one. Mine was pretty
cracked, so I got a new one
at NAPA. Now you can remove the power steering pulley. You should loosen
the bolts with the
serp belt still on as it provides something to hold the pulley in place
while you loosen the bolts. Next
step is to remove the passenger side timing belt cover, the driver's
side cover doesn't need to be
removed. After you remove the cover, you should use and inspection
mirror to locate the two bolts
that hold the T-stat cover in place. Now is the time to drain radiator
fluid. Mine was still in good
shape, so I saved it and reused it. Drain as much as you can. Once that
is done, loosen the hose
clamp that holds the lower radiator hose onto the T-stat housing, then
pull off the hose, you might
lose some more coolant at this point. Now remove the two bolts holding
the T-stat housing on.
Next step is to remove the T-stat housing. You will have to pull out
towards the front, while
twisting the timing belt a little to give yourself clearance. While
pulling outwards from the block, try
to move it down and to your left. Imagine a straight line running from
the round buldge on the T-stat
housing to the outlet, try to follow that line. With a little
persuasion, you should be able to remove
the T-stat housing entirely following that line, then pull it out of the
engine compartment completely.
Note that the T-stat sticks out about 1/2 inch, and you need to pull the
housing out towards the
radiator to clear the T-stat. Once you have the housing removed, you can
pull the old T-stat. Note
that the O-ring is on the outside of the T-stat, this is what the
housing seals against. I cleaned the
mating surfaces of both the block and the housing with a Scotch-brite
pad. MAKE
ABSOLUTELY SURE YOU CLEAN BOTH SURFACES! Otherwise you will have leaks,
I'm
speaking from experience. I failed to check the orientation for the
little bleed valve in the T-stat, a
call to the local Audi dealer, and they told me the bleeder should go
up, as I thought. If anyone
knows different, feel free to correct me. Anyway, that's how I installed
my new T-stat, with the
bleeder valve at the 12 o'clock position. Just reverse the steps to put
it all back together. Once you
have it all together, add in as much coolant as you can. Locate the
bleeder valve on the upper
heater hose, that will be a very handy place to bleed out air from the
system. Start up the engine
and park the car with the tail end up higher that the front end, this
will help to bleed air out of the
system through that bleeder on the upper heater hose. Make sure your
heater is turned on so that
you get coolant flow through the heater core. Now it's just a matter of
patience to make sure you
bleed as much air out of the system as you can.
--
Todd Young
7079 Dawn Ave.
Inver Grove Heights, MN 55076
651-450-7725