RE: After-run relay failure?

["Avi Meron" <avi@cosmoslink.net>]

Sorry to hear you bought a pump, the Audi (Bosch) pumps are not good pumps
(I replaced 2 in the last two years). I suspect many people are running
around with none working pumps.
I found a source that has a much better pump (for the purpose of cooling
small blocks) and I am in the process of adapting it to the Audi.
I will keep you and the list informed, BTW it is cheaper than the Audi pump.
Avi

-----Original Message-----
From:	owner-quattro@coimbra.ans.net [mailto:owner-quattro@coimbra.ans.net]
On Behalf Of Wallace White
Sent:	Friday, January 29, 1999 11:03 AM
To:	Quattro
Subject:	After-run relay failure?

I recently replaced my secondary / auxillary / turbo coolant pump (pick
your favorite name) but hadn't verified that it was really working until
recently. Pulling the 1st stage radiator relay and shorting the
thermoswitch proved that the pump was _not_ running. Power straight to
the pump ran it fine. DMM showed that there was no voltage across the
pump wires when there should've been.

Wiring to the thermoswitch, pump, and after-run relay checked out fine.
Upon taking the cover off of the after-run relay, everything looks fine
except that one tall, flat component looks possibly fried. This
component is right next to the connector pins of the relay, and it has
an exposed metal plate on one side and a hole through it--probably for a
heat sink that might have saved it, if it were there? I'm not terribly
familiar with transistor packages, but I would guess that this was the
high-current transistor for the pump.

The old pump had seized and was probably like for a long time, so this
transistor may have died trying to provide stall current for the pump
for a long time.

All right, I think, I'll just get a new relay and see if that does it.
TPC doesn't have them, and Linda warned me before telling me that it was
$78. So it wouldn't be a cheap experiment to buy a new one and pop it
in. Can anyone say whether the relay really is the problem, or how to
check? Or maybe this would be a good time for me to finally make a trip
to a junkyard. The relay is 447 965 571 A, in case anyone has one.

Let's see, $120 for the pump, $40 for the special hose to the pump, $78
for the relay... at what point do you spend more trying to protect the
turbo than the turbo itself costs? Just kidding; I don't really want to
know!

Thanks in advance.

- Wallace
  '87 5kcstq 151k