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Re: Water circulation pump?
In addition to what Avi said... Whenever the radiator fan comes on after
you've turned the car off, the aux water pump turns on at the same time.
The after-run relay runs the fan and pump until the coolant temperature
(measured by a two-wire thermoswitch on the coolant output flange) drops
to an acceptable level or until a timeout (10 minutes?).
The fan by itself doesn't do a whole lot to decrease the coolant
temperature at the engine block, so cars with dead pumps tend to have
their radiator fans running for a long time after shutdown (often the
full 10 minutes or whatever) instead of a couple of minutes. Some people
have found this electrical drain to make starting afterwards difficult;
I suppose this is especially true for cars with a weak alternator or
BTW, a seized pump often causes the after-run relay to fry one of its
transistors, so that a new pump won't run. If so, not to fear: there's a
$1 Radio Shack part (NPN TIP 31, I think) to fix that.
The pump costs about $120 at the cheapest (The Parts Connection has them
on sale sometimes) and the pumps are not known for long-life. Avi's
altnerative certainly sounds promising.
'87 5kcstq 152k
Jack Gagnon wrote:
> I noticed an electric water pump in my 87 5kcstq and a previous owner
> bypassed the pump for some reason. My mechanic said it is to cool the turbo
> after the engine is turned off. Why would it be necessary to bypass it? and
> if I let the turbo spool down for a minute or two before shut-down is it
> necessary? I will probably fix it soon, but I need to earn some more money