[urq] Cooling System question- update
spotatashleys at hotmail.com
Mon Oct 22 13:08:49 PDT 2012
I don't think there is any doubt now. I went for a short trip to town and
when I got to town (2 miles) the system was under great pressure. I let it
cool and then drove home and once it had cooled down again I removed the
plugs. 2,3,4 & 5 were fine - a little darker than I expected but it had just
run on rich mixture. No1 plug was black and was really hard to remove due to
what I found was rust on the thread. Shining a torch down the plug holes -
revealed 2,3,4 & 5 had a blackish oily film on their surface but nothing too
bad but No1 was shiny clean aluminium and looked a bit damp. I rolled up a
piece of newspaper and pushed it in to the plug hole and soaked up some
drops of liquid which smelled of antifreeze. There's no water in the oil, so
I'm hoping I've caught all this in time but I guess I'll only know if there
has been any damage once I strip it down - which I'll start next week once
I've bought all I need for head gasket change (gaskets, bolts and beer). It
will be interesting to find what has caused this. The engine is 10 years and
33000 miles old and despite this trouble runs fine. I reckon the recent and
occasional odd spots of coolant on the garage floor were overflow from the
header tank when the pressure got too great. I guess I have been lucky the
heater matrix didn't fail.
So, off the road for the winter now.......
Thanks to all who answered my appeal for thoughts and guidance. No doubt
I'll be back on the list if I encounter bad things!
Thanks again and all the best
'87 WR in darkest foggy Worcestershire.
From: Chris Miller
Sent: Saturday, October 13, 2012 9:50 PM
To: 'Keith' ; urq at audifans.com
Subject: RE: [urq] Cooling System question
I'd replace the cooling overflow bottle cap if you are concerned about
pressure in the system; I believe that is the pressure relief valve in the
Easy ways to test for the head gasket leak (into the combustion chamber)
include checking the plugs; the really clean cylinder may be leaking; also
there are test strips you can use in the coolant to see if there are
combustion gasses present.
As for possible leaks:
If it is leaking to the outside of the engine, not into the cylinders, I
think you'd see a stain on the block. Pull the lower engine cover and see.
The later cars came with an after run electric cooling pump, I believe; not
sure when that started. They are plastic and can crack and leak. Do not
check them when hot as they can break open and douse you and cause a severe
burn. Similarly the control valve for the heater core is plastic and can
Another possible spot for a leak is the water pump; sometimes they seep but
it would be difficult to see with the belt guards in place.
There is also a small tube across the front of the block, behind the inner
belt guard against the block. On my 20v motor, it has a rubber hose on each
end; I think that is the water return feed from the turbo. The feed is
below the turbo off the block.
From: urq-bounces at audifans.com [mailto:urq-bounces at audifans.com] On Behalf
Sent: Saturday, October 13, 2012 4:27 PM
To: urq at audifans.com
Subject: [urq] Cooling System question
I have some curious goings-on with my quattros cooling system. On occasion
but not always there are one or two drops of coolant on the garage floor.
The system does indeed lose a little, but so little as to be unable to trace
the source. The running temperature is absolutely normal but the cooling
system remains pressurised even when the engine has cooled right down. The
engine runs fine. I have searched on line for possible causes of the system
remaining pressurised, some suggest a leaking head gasket. Obviously I do
not want to remove this just to look and there are no other signs that I am
aware of to suggest HG failure. I will be surprised and not a little
disappointed if the HG is failing because the block was Wills ringed when I
built it (10yrs ago though) to ensure a good seal around each cylinder and I
don;t thrash it (in fact my friend ridicule my mechanical sympathy for my
car!) I guess the question is: should I be concerned? Are there any tests I
could do to confirm/deny HG failure given the current minimal outward
symptoms? The amount of residual pressure in the system when cold is what
concerns me the most though.
Any ideas/suggestions gratefully received (as always).
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