[Biturbos4] Strange loss of coolant

[Paul Caouette]

Our 98 A4 had similar problem. I discovered that the dumb ass mechanic who
pulled the radiator hadn't slipped the lower radiator hose completely. The
clips weren't engaged but the hose was on tight enough to not leak except
when the system got pressurized. I had a good time yelling at him...
...
Later my wife asked me, 'Why were you swearing so much while you were under
that car?"
I said, "That old dumb ass mechanic did some shitty work last time."
She said, " You're the only one who works on that car."
I said, "He still did shitty work."
I think she's considering calling the guys in white to take me for a little
ride in the country.

On Sat, Jul 2, 2016 at 6:48 AM, Kneale Brownson <kneale at coslink.net> wrote:

> Take off the belly pan, Ti.  My wife's Allroad developed a leak in the
> cramped hose to the oil cooler.  You can see the hole in the hose at
> http://www.pbase.com/kneale_brownson/image/156860076
>
>
> On 7/1/2016 11:25 PM, Ti Kan wrote:
>
>> Hi folks,
>>
>> Thanks for comments from Al S., Andrew Lundy, Kneale Brownson, Geraldo
>> Candela, John Lag see, Mark Rosenkrantz, Chris Semple, Dave Eaton and
>> Wylie Bean.
>>
>> Here's an update to the problem.
>>
>> After driving for a few days (over 100 miles) with apparently no
>> more coolant leaks, today I noticed a leak again.  It occurred right
>> after shutting off the car from an ordinary 20-minute drive in
>> about 85 deg. F weather.  The puddle below the car suggests no more
>> than about one quart lost, and that's how much I had to refill to
>> get the level up to normal again.  Then, I was able to drive around
>> for the rest of the day without any further leaks.
>>
>> While looking around under the hood, what I do know is that the leak is
>> not coming from the coolant reservoir or the cap.  Everything looked
>> dry, there is no G12 residue anywhere that I could see, and the sound
>> absorbing liner under the hood was also dry with no sign of hot steam
>> on it.  Of course the engine bay in an S4 2.7T biturbo is quite cramped
>> and one couldn't see much through the gaps.  I did not remove the
>> under-engine cover to look at the bottom side.
>>
>> I also know that it's not a problem with the electric radiator fans.
>> They operate just fine when I turn on the A/C, and also when the after-run
>> auxiliary coolant pump is activated.  Btw, I am running a lower than stock
>> temperature switch for the auxiliary coolant pump and fans, so that it
>> helps to cool things down after shutting off.
>>
>> It's also not likely to be an internal leak (i.e., into the combustion
>> chamber).  There is no smoke out the tail pipes, the engine oil
>> level looks normal, with good color with no sludge on the dipstick.
>>
>> So right now I think I've narrowed it down to two possibilities:
>>
>> 1. A pin-hole on a hose somewhere that leaks only when above a certain
>>     pressure.
>> 2. Electric auxiliary coolant pump
>>
>> #1 would obviously explain why I lose coolant only occasionally,
>> but would #2 also exhibit a similar symptom?  FYI my auxiliary
>> coolant pump was replaced a year and 3 months ago.  That would be
>> a really short life if it had gone bad...
>>
>> -Ti
>>
>
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-- 
Paul Caouette