quattro digest, Vol 1 #3849 - coolant flushing, refilling

[Larry C Leung]

Brett,

Don't meam to make it sound dumb but, is the fan temp switch hooked up?
(ask me how I know...)

LL - NY


> Date: Fri, 16 Aug 2002 21:14:39 -0400
> To: quattro at audifans.com
> From: Brett Dikeman <brett at cloud9.net>
> Subject: coolant flushing, refilling
>
> So I finally decide to tackle changing the coolant, which looks
> pretty disgusting, and sure enough, when I drain it, it comes out a
> very nasty dark brown.  Ugh.
>
> So fill it up with fresh tap water, run it for a while, drain that,
> comes out still pretty brown/green.  Repeat.
>
> I'm finally getting something pretty reasonable-looking, but I
> being
> to wonder if I'm not getting all the coolant out; I'm draining from
> the bottom aux radiator hose, which is supposedly the lowest part
> in
> the system- yes, engine is fully warmed up, yes, the ignition is on
> and the temp set to HI.
>
> Each time, it takes about 4-4.5l of water to fill up the system,
> and
> it doesn't seem like the car sucks all that much down- I was
> expecting to have it settle with the car off, start the car, have
> it
> suck the reservoir down, and I'd have to add some more- nope, not
> really.  Maybe a little..
>
> After running the prestone coolant system flush, I fill up with
> fresh
> water again, and as per the Bentley, let it run waiting until the
> stage II fan kicks on, add coolant as necessary, and move on.
>
> Never happens.
>
> I get a little spit up(this happened a couple of times before, and
> only once), but instead of the fan immediately kicking on(as
> usually
> happens after the slight spit-up), it stays off.
>
> And stays off.
>
> Coolant gauge stays straight up, pretty much the entire time, and
> next thing I know, I've got a bubbling geyser.  Crap- the car is
> boiling over.
>
> Shut it off, flip on the afterrun circuit 'hotwire' switch I have,
> and dump water in.  Capped it, turned on the engine, and let it run
> to even everything out.
>
> It never boils over with the cap on, so my thought is this- is the
> Bentley procedure really only for when you've got water AND coolant
> in the engine, not just water?  Perhaps the t-stat is sticking, or
> is
> the wrong temperature?  Stage II temp sensor wrong temp or
> sticking?
>
> As a side note, I'm embarrassed- the coolant system was clearly
> neglected by yours truly.  Even after 4 flushes, I'm still getting
> scale and rust bits, and only now is the water coming out a
> reasonable color...egad...
>
> Brett
> '91 200q20v
> --