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Re: Heat, or lack thereof in MGB

To: Bud Krueger <>, MG List <>
Subject: Re: Heat, or lack thereof in MGB
From: Bob Allen <>
Date: Sat, 06 Mar 1999 13:37:16 -0600
>     These chilly mornings (temp about 20F) have left me with a desire for
a bit
>more heat. (that's an understatement.)  The 77B, with a 190F thermostat,
>up quite readily according to the temperature gauge, and the heater blower is
>rather loud.  The problem is that the air coming out is barely warm.

Well, Bud, there is a fast and wet way to do this or a slow and dry way to
do it. It's up to you. What I've found is that an MG heater is quite
effective, if in good order, and it has nothing to do with the fan. The fan
is only handy at slow speeds otherwise the air into the cowl duct is enough.

Anyway, heater problems have two sources -- the core is clogged or the air
isn't being directed through the core. From the inside, the core can get
clogged from the usual suspects and the only fix is to reverse fluch at
fairly high pressure. You can cobble up a some heater hose and garden hose
fittings to back-flush the core using the usual methods, while it is still
in the car and you will likely have reasonable results.

Unfortunately, you have to take the heater box out to do a proper job and
that is a bit of a bitch. Especially if you don't know about the cable
connections and distribution tubes that must be disconneted while sitting
on your head in the cockpit. The heater box _will not_ come out by merely
undoing things from under the bonnet and yanking real hard. (Trust me.)

Once you have the box out, you want to do three things:

1.) Clean the interior of the core using the above methods but, now that it
is out, the cleaning can be supplemented by adding a little draino or
toilet cleaner to the core and letting it sit for ahwile. Then pressure
flush and control where the effluent goes.

2.) The other thing is to clean out the passages between the fins. You
might be surprised by the amount of debris that can get lodged in there.
When clogged, the air has to run around the core on the sides of the air box.

3.) When putting it all back together, use foam tape to form a seal on the
outsides of the core. That is, use foam to seal the spaces between the
outside of the core and the inside of the heater box. That way, all the air
going through the heater box must pass through the core and cannot work
around the edges.

Once properly R&R'd, the heater should be quite sufficent to clear the
windscreen and raise large blisters just below your inboard knee. You can
do the remove and R&R on a weekend if you don't dawddle or imbibe much. At
least I should think so. But I usally go a little anal and spiff things up
with some rattle cans of black enamel and that makes it a three day job.
(The first time it took a week to replace all the connections in the
cockpit I buggered up.)

Bob Allen, Kansas City

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