overheating 4000q

[George Nimmer]

Yes, I replaced everything and all replacement parts were brand new Audi
or OEM components.  I replaced all the cooling system components because
of this unusual overheating.

The coolant was flushed a few times because this overheating caused me
to blow the head gasket earlier in the summer :-( and I was getting oil
in the coolant, and I was burning a lot of coolant out the exhaust.
Since replacing the head gasket (BIG pain in the arse), those symptoms
have gone away, and I've been very careful to keep my highway speed at
60 mph or so, so as not to overheat and blow the gasket again.

I'll have to get out the Bentley to check on the control pressure, as
I've never done this before.  I haven't checked the ignition
timing/advance recently, but I'll make a point of it this week.

I've checked the plugs several times, and they don't _appear_
overheated.  They have a very smallish amount of light grey deposits on
them with no blistering of the insulator nose, or excessive electrode
wear or excessive gap.

Thanks


On Wed, 2002-09-11 at 12:46, Bruce Bell wrote:
> 87 is correct for the thermostat. Did you replace everything, radiator etc.,
> because of the overheating problem? You said you flushed the system after
> all the replacements. Did you suspect some of the parts? Could the radiator,
> if used, have some blocked cores?
>
> My first thought is you are running a bit lean (creates extra heat). Check
> injectors system and control pressure. It also wouldn't hurt to make sure
> you aren't running too much ignition advance. Set it at the factory spec 8
> degrees or better yet make sure you aren't running more than 34-36 degrees
> total advance. It would be interesting to see the plug colors after one of
> these overheating runs.
>
> Good luck
>
> Bruce
> 98 A4 2.8qm 70,000
> 87 4kq 300,000
> 84 quattro 50,0000
>
> -----Original Message-----
> From: quattro-admin at audifans.com [mailto:quattro-admin at audifans.com]On
> Behalf Of George Nimmer
> Sent: Tuesday, September 10, 2002 10:37 PM
> To: quattro at audifans.com
> Subject: overheating 4000q
>
>
> I have a puzzling problem with my '85 4000s quattro overheating.  It has
> 156k miles on it.
>
> Again, it only overheats when driving for 15 mins or more, at greater
> than 70mph, when outside temps are 90+.  It does this whether or not the
> A/C is on.
>
> It runs cool as a cucumber when the A/C is on high and I'm stuck in
> traffic, driving in the city, or crusing at only 60mph, even when
> outside temps are 100+ degrees.
>
> I have replaced the water pump, thermostat, coolant expansion tank, all
> coolant hoses, the radiator, radiator fan, water temp sender, and
> flushed the coolant more than a few times.  I'm running a 50/50 mix of
> distilled water and G12, and there are no leaks in the system.  In
> addition, I had the coolant system pressure tested at the local VW/audi
> independant shop, and had them ensure there were no air bubbles stuck in
> the system.
>
> What other components could I possible check???
>
> The engine starts and runs marvelously, revs cleanly and smoothly all
> the way to redline.  it is meticulously maintained, and I've taken
> several recent ~500 mile drives without any problems whatsoever (with
> the exception of the aforementioned overheating under certain conditions
> situation).
>
> Ideas?
>
> Thanks.
>
>
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