Heater Core Problems on 1989 90

[rlliss at rockwellcollins.com]

Thanks for the additional comments.  You and Dave gave me the added
confidence that I might try to dig into this problem.  It has to be done...

I have performed some of these suggestions already.  I did change out the
Thermostat and flushed the core as suggested at the begining of this saga.
So I think I will work down the list.  I pulled down some instructions from
your web site that make the job also seem more manageable...

Thanks Again Guys...



                      Huw Powell
                      <human747 at attbi.c        To:       Dave Hord <spokes at the-wire.com>
                      om>                      cc:       rlliss at rockwellcollins.com,
                                                quattro at audifans.com
                      01/21/2003 12:58         Subject:  Re: Heater Core Problems on 1989 90
                      PM
                      Please respond to
                      human747






> > Help, it is cold out here in the midwest and my Heater Core looks like
it
> > has bitten the dust.  Has anyone performed a corectamy lately.  How
much
> > work is involved?  Is there an alternative until Spring?  I have tried
the
> > Prestone Flush with no results.  I have also noted that my temp sensor
in
> > the dash is no longer reading temp since I flushed it - can the flush
have
> > affected the sensor?  Nearly Frostbitten...

I think Dave is right, you probably have some other issue.  Comments
added below.

> Howz your thermostat?
>
> I'd check the following:
>
> 1) Temp gauge sender.  Fix it so that you can see how hot the coolant is
> getting. In the meantime, stick a thermometer in the coolant resevoir to
get a
> good idea...

Agreed.

> 2) Thermostat - If the engine isn't getting up to operating temperature,
your
> heat is going to SUCK.  BTDT this week, yesterday in fact. Now I'm
TOASTY!

Again, a $10-15 part, not too hard to replace, should really be done
every year or two.

> 3) The heater core can fail in three ways (that I can think of): a) valve
> fails..therefore you move it to heat and get NOTHING. b) core
ruptures/leaks,
> fogging up your window and making a STINK. c) clogged. Never heard of it
> though...

Again, right on the money.  The type 89 (your car) does not have a
heater valve for the fluid, there is a flap that routes the incoming air
through or around the core.

To *really* flush your heater core, undo the hoses to it at the firewall
(be prepared to replace them) and blast nice clean hose water through it
both ways for a bit.

> Replacing the heater core is a PIA!!  You have to pull the whole dash,
then the
> whole heater blower/AC/heatercore that's behind the firewall.  Not fun.

While I broadly agree here, and would have agreed even more in the past
(from dismantling a parts car), I recently had the opportunity to snag a
black interior out of a wreck.  It took me about two hours to remove the
whole thing, from parcel shelf to dash.

Next door a 90Q that suffered engine damage to a neglected leaking
heater core is undergoing restoration by one the techs (who now owns
it).

It took him about an hour, working comfortable slowly, to get from
"dashboard out" to "heater core out".

I agree it is a daunting job, but it is not really as bad as it seems.

One hard part, though - when you have the HVAC plenum loose, you must
separate the left half, which houses the core, from the right half,
which houses the fan and AC evaporator.

There are six clips to pry off.  The two on the fron are visible, as are
the one on top and one on the bottom.

The two on the rear cannot be seen, but mirror the front ones, and can
probably be slid up and down (for upper one and lower one) to remove
them blind.  Otherwise you end up having to force the two boxes apart
and some plastic will probably break.

--
Huw Powell

http://www.humanspeakers.com/

http://www.humanthoughts.org/