Water pump failure? Probably!

[Doyt W. Echelberger]

I replaced the water pump on my 87 5ktq at 258k miles a few weeks ago.
Essentially the same symptoms as you describe, Roger. However, I discovered
a way to make the final diagnosis: Remove the small overflow rubber hose
from it's attachment to the reservoir, being careful not to exert undue
pressure on the plastic reservoir nipple, and back-fill the radiator
through it.

Using a turkey baster, insert the baster tip into the free end of the
rubber overflow tube and back-fill the radiator with repeated applications
of the contents of the turkey baster. Perhaps as much as a quart of fluid
over a few minutes of dipping and squirting. You can use a 50-50 antifreeze
solution, or just plain water.....it will run out anyhow if you have a
leaking water pump.

The back-fill process loads the coolant channels that lead to the pump,
creating a head of pressure.  The coolant leaks out rapidly through any
openings associated with the pump, and the leaking coolant trickles down
the front of the engine and runs down the passenger side of the serpentine
belt pulley, across the junction of the block and oil pan.  Have an
associate peer at this area using a flashlight, as you back-fill the
reservoir hose.

My vehicle was only leaking visible coolant while it was being driven, and
the air flow swept the coolant across hot engine surfaces, where it
evaporated without a trace. When I stopped, there wasn't any coolant left
in the pump system, and I couldn't detect any trickles .  So I suspected a
leaking head gasket as a source of the disappearing coolant. The leak was
so bad that the radiator would boil over after about 15 minutes of
driving.....but I was puzzled as to the source of the leak, since I was
never was able to demonstrate a coolant trickle from the stationary car.

Finding the tell-tale trickle after the back-fill was a most satisfying and
anxiety relieving experience.  We replaced the water pump and all has been
well with the cooling system. Almost anything is better than a leaking head
gasket, in my opinion.

Hope this is useful to other listers afflicted with mysterious coolant loss.

Doyt Echelberger
87 5ktq in Ohio   USA


 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
At 04:56 AM 11/2/2002 -0500, you wrote:
>Got the friendly, ominously red, low coolant warning on the '94 100CS Avant
>Quattro yesterday morning.  Pretty lousy, really, as my wife and I were
>heading out to go shopping, 35 miles away.  Mileage is 59,700+, so I know it
>is probably timing belt time.
>
>Popped the hood and notice the resevoir is down to near bottom, hence the
>warning, and, worse still, some wet on the panel under the serpentine belt
>pulley.  Not to worry. Callled the friendly local dealer....100 miles
>away....and made an appointment for next Thursday...timing belt, water pump,
>tensioner to be on hand if necessary, also pull codes for mysterious
>intermittant "check engine" light, and fix the interior light delay, which
>doesn't....
>
>Filled the resevoir with coolant, and drove away to do my local stuff, and
>returned to pick up my wife.  Noticed a LINE of antifreeze leading from
>where I had turned to about thirty feet up the driveway.  "Uh, oh," thinks
>I.  "Water pump maybe seriously leaking."  Could a flat bed be in my future?
>
>My wife and I drove to Bangor and returned without incident.  We may luck
>out.
>
>The history is this.  The car was owned by the a woman who is a part of the
>family that controls one of the largest motor freight companies in the
>country.  The car was (apparently) religiously maintained by the local
>authorized dealer, and it would appear, on a "cost no object" basis.  I
>bought the car last year with 39,000 miles on it.  Just before I bought the
>car, the 45,000 mile service was completed....as stamped in the book by the
>authorized dealer.  Now, I had rather assumed that the timing belt probably
>had been done at the six year point, for age, but now I am not entirely
>sure.  At any rate, it would seem that the car will stagger the 100 miles
>for service next Thursday.
>
>At least I hope that it is the waterpump leaking, and not something far more
>ominious, although there is no sign of that.
>
>While at the dealer, I will be driving a new VW TDI of some sort.  It might
>well just replace my V8 soon, or I might wait a bit longer, and try out a
>new Tuareq, which so the dealer tells me, IS expected to be imported with
>the TDI 10 cylinder engine.....500 lbs of torque, and TWENTY-FIVE  miles per
>gallon!  Holy SUV!!
>
>Roger