[Vwdiesel] overheating redux

[David Cook]

On my Corrado, whenever I've had to drain the coolant
for some reason, I will have to fill it up, then take
it for a drive, and after a few minutes the coolant
light will flash.  At that point, I pull over, pop the
hood, and crack the res. cap to *carefully* let the
pressure out of the system.  Sometimes at first I have
to crack it and close it again two or three times
before I can just crack it and wait for the pressure
to  release.

At that point, I just have to refill the res and I'm
good to go.  (This is effectively burping the system)

You said you checked the fluid level at the parking
lot, did you when you got home?

Sometimes an airbubble will happen at the thermostat,
which won't allow the hot water to make contact with
it so it can't open.  Sometimes massaging the coolant
lines can help this.

I have also heard of people drilling a tiny hole in
the thermostat to allow it to burp itself.

Others have recommended disattaching the top coolant
hose off the head and filling from there along with
the res.

Sometimes you kind of have to just test and see what
works for that particular car, I think.

David
 

--- "S. Shourds" <sshourds at flash.net> wrote:

> This weekend, I finally lit a fire under myself and
> replaced the 
> thermostat in the TDI.  Enthusiasm has not been
> high.  I got it 
> together, changed the oil while I was at it, and
> started it up.  
> Everything looked fine.  I drove it to a car wash to
> de-grease the 
> engine in the interest of tracking down a small oil
> leak.  The 
> temperature was fine.  I drove a few more miles and
> then hit the 
> entrance ramp on the highway.  Just as I'm hitting
> warp speed and 
> beginning to merge with traffic, the dash starts
> beeping and flashing 
> "ABS".  I also notice at this time that the
> temperature gauge is heading 
> straight to the red.  I hook a hard right at the
> next exit and while 
> waiting at a yield to get back home, I reboot (shut
> off and restart) to 
> at least get rid of the ABS light.  Curiously
> enough, at this point, the 
> temp needle drops to dead center.  I drive a little
> ways farther on a 
> surface street, and the temp needle is going high
> enough to give the 
> overheat warning light.  I shut off the engine so as
> to not overcook it 
> while I wait for a hole in traffic to dip into a
> parking lot.  30 
> seconds later, I restart, plow through a small hole
> in traffic, and look 
> down at the gauge:  dead center.  I pop the hood. 
> Fluid levels normal, 
> upper hose too hot to handle, lower hose just a
> little above pleasantly 
> warm, the coolant fan is cycling on and off.  The
> thought occurs to me 
> that the cooling system could be working fine and it
> could be an 
> electrical problem, particularly as it occurred
> simultaneously with the 
> ABS warning, which, when VAG-COMed indicates "Supply
> voltage at terminal 
> 30 outside range, intermittent." 
> 
> The sole caveat is that when the temp gauge went up,
> the first thing I 
> did was crank the heat to max.  I never got any
> heat.  I did, of course, 
> drain and refill the coolant system when I replace
> the thermostat.  If 
> there was a bubble in the heater system, could that
> make a problem on 
> these lines?  I know the IDI engines were bad about
> getting bubbles, but 
> I don't know about the TDI.  Everything's so
> strangely different (they 
> take the same thermostat, though).  I did fill
> according to 
> instructions:  slowly into the reservoir, warm up
> the engine, cool, and 
> top off.  I had coolant at the upper hose.  I wasn't
> getting solid flow 
> at the coolant reservoir hose.  At least I don't
> think so.  The memory's 
> vague on that point. 
> 
> As far as the electrical concerns, the CD version of
> Bentley won't let 
> me see the wiring diagrams.  It just chokes.  Anyone
> had that happen? 
> 
> So the questions:  I've filled and drained this
> thing a couple times 
> before and had no problems.  Anyone know where a
> bubble might be hiding?
> 
>                             Anyone know if the ABS
> connection to 
> "terminal 30" and the temperature sensor pass
> through a common 
> junction?  I've already had a few problems with the
> harness right under 
> the drip shield                             between
> the wipers--there's 
> a big hole in it someone cut to access that
> junction. 
> 
>                             Anyone else had problems
> with the Bentley 
> wiring diagrams?  The computer's really flaky
> anyways so who know what 
> the problem there is. 
> 
> 
> 
> BTW, my DVD drive won't give me any sound when I try
> to watch a movie 
> and even my oven popped an error code, so it's just
> sort of been like 
> that lately.  I'm thinking of running away and
> joining the Amish. Of 
> course then, my chickens would get bird flu. 
> 
> 
> -Shalyn
> 
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> 


David Cook
Red '86 Cabriolet Diesel Powered
Red '90 g60 Corrado 
Brown and White '78 Westy Campmobile "Bear"
and others in various states of disrepair
Pictures here: community.webshots.com/user/superdave5599

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