1990 200Q radiator blew up

[Ben Swann]

Stacy,

I'm too tired and pressed for time to reiterate a similar saga that I went through while driving a similar car home to perform service for a friend, but basically, the headgasket was blown (or starting to go)when your freind got the car.

Expect to find a myriad of coolant system related problems due to the increasing pressure that was being caused as the headgasket went from leaking a little 'til the time it went when engine under full load - probably resulting in a warped head when that happened.

Now for the bright side.  Nothing like a complete teardown and rebuild - at least the head to make sure the engine is ready for full boost.  Make sure the head is decked or better yet, replaced.

Ben

[From: "Stacy" <qturbo at tiedyed.us>
Subject: 1990 200Q radiator blew up
To: <quattro at audifans.com>
Message-ID: <SKYNET382gI2JMldVAt000003ab at skynet3.skynet.skynet3.com>
Content-Type: text/plain; charset="us-ascii"

Last night, as I was about to fall asleep I my cell phone rang, and seeing
it was a friend of mine that had just purchased a 1990 200Q that we had been
working on earlier in the day I decided to answer it, even though it was
1:03AM.  What he had to tell me was at first funny, and then later not so
funny. A little background on this situation. 

When he first bought the car, he brought it over to my place to have me
check it out. It looked to be in very nice condition, the only problems we
spotted at this time, was a lack of full boost, and that the after-run
system seemed to be freaking out (upon closer inspection it appears that the
thermo switch is toast). I also took the coolant tank cap off and looked
inside, and then put it back on

When the car was idleing a few minutes later, I hear and felt this thumping
noise from the drivers side footwell area. I think oh no! theres a problem
with the fan, I turn the ignition off and we pop the hood and take a peek,
the radiator overflow hose is producing large bubbles in the expansion tank
that are thumping hard enough to be felt in the passenger cabin. I have
owned a 1986 5000CSQ for 4 years and had never experienced anything like
this, we found that we could stop the bubbling by tightening the expansion
tank cap. Later my friend took the car on a quick drive, when he was
cruising on the highway the low coolant alarm went off and he popped the
hood and the tank was boiling and the cap (a new one, he replaced the old
one) was whistleing. When this was happening the temp gauge was reading on
the high end of the 'ok' range, if you look on SJMs site under cooling
systems he has a diagram that shows a 'normal' range, and the gauge was
reading on the high end of this. Also about this time, he noticed that there
was condensation on his windshield, on the inside, over the defroster vent.

 

Flash to yesterday, we had tracked down the boost problem, (torn turbo -> ic
hose) and fixed it using a length of off the shelf radiator hose of the
appropriate diameter ;-) . We also replaced the radiator fan thermo switch
mounted in the bottom of the radiator. The old one was highly corroded.
Everything at this point seemed to be working great. Here is the part that
is funny, my friends significant other, has had 'experience' with my friends
other cars. He always seems to have a car with some sort of 'unique' issues,
and she is especially leery of his Audis. (a previous 5000S fwd auto had a
wheel that would lean 30 degrees when turning a corner, and an 88 80q burst
into flames and burned to the ground...) Well, he asked her to come for a
ride in his latest Audi, and she agreed, but not without first putting on
some warm clothes, when he asked her why the warm clothes, she replied that
it was incase the car broke down..what confidence!


Well, he took her for a 20 mile ride to a hill that is long and fairly
straight, to show her, 'what a turbo can do'. Once at the hill he laid into
the throttle and started passing another car going uphill, when all of the
sudden he heard a popping 'gooshing' noise. And steam/smoke erupted under
the hood, also inside the passenger cabin, and on the passenger footwell. At
this point his SO yelled at him to pull over. When he looked under the hood,
he noticed that the end tank of the radiator had blown off. It also seems
that the heater core blew at the same time. As there was a mist of coolant
sprayed on the windshield while they limped the car home over the next 2 and
a half hours (he forgot his cell phone at home). What could cause enough
pressure to blow the radiator and heater core up like this? Blown headgasket
dumping compression into the cooling system? Clogged radiator? Any help is
greatly appreciated.


Thanks in advance!
 

Stacy]