Subject: Re: [Mgs] Heater Air Control

From: Andrew Lundgren <[email-masked]>
Date: Mon, 25 Nov 2013 09:08:17 -0700

On some years there is not enough travel in the heater control lever/knob
to fully open the heater valve. Some people adjust it so that it will not
close all the way in the winter and then again when it warms up so that it
doesn't open all the way.

Someone posted a long time ago about reworking the value to get more volume
through it. It has pictures and was on a website.

My experience is to be careful with that value. They put it right above the
distributor, and it is known to fail, dumping coolant.  I ended up using a
bit of an aluminum can to block mine of when it broke and soaked my
distributor one year.
On Nov 25, 2013 8:36 AM, "Mark" <[email-masked]> wrote:

> Here is my first post regarding my recently acquired 67 BGT.  I was
> sorting out the heater air flow control mechanical switch this weekend and
> ran into a problem.  The spring on the shaft of the air control that holds
> the knob is missing.  Someone in the past had put a set screw in the
> plastic knob that fit poorly in hole in the shaft that held the detent.
>  The switch works but not well.  I see that the usual sources don't have
> the replacement switch and the plastic won't hold the set screw for long.
>  are there any good options to fix the shaft?  Maybe a replacement spring
> and detent?  I also have minimal flow of hot water through the heater core
> and have ordered a new heater control valve.  I need to flush the cooling
> system anyway so I will replace the valve when empty the radiator.
>
> Thanks,
>
> Mark
> Nashville
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From: "PaulHunt73" <[email-masked]>
Date: Mon, 25 Nov 2013 16:57:54 -0000

Anything in the heater circuit can cause reduced flow, including the core 
itself and the metal pipe that carries the return flow back to the bottom 
hose.  Unfortunately replacement valves are pretty poor, The original lasted 
30 years, the replacement less than 10.  If the detent is missing but the 
hole is clear I'd tap the hole and uses a grub-screw, even if you could get 
the correct control (and there are many with different configurations) they 
are expensive.  Either that or get a cheap second hand one and if the wrong 
type perhaps swap the spring and pip over.

PaulH.

----- Original Message ----- 
> ... The spring on the shaft of the air control that holds the knob is 
> missing. 

[email-masked]

---

From: Mike E <[email-masked]>
Date: Mon, 25 Nov 2013 12:38:31 -0500

Mark,
I may have an air control mechanism from a late '70s pillow dash roadster that
I could send you.  Maybe someone else here would be kind enough to verify that
it will fit your '67 BGT?
Cheers,
-Mike Eldred
Wilmington, VT

> Date: Mon, 25 Nov 2013 09:34:54 -0600
> From: [email-masked]
> To: [email-masked]
> Subject: [Mgs] Heater Air Control
>
> sorting out the heater air flow control mechanical switch this weekend
> and ran into a problem.  The spring on the shaft of the air control that
> holds the knob is missing.  Someone in the past had put a set screw in
> the plastic knob that fit poorly in hole in the shaft that held the
> detent.  The switch works but not well.  I see that the usual sources
> don't have the replacement switch and the plastic won't hold the set
> screw for long.  are there any good options to fix the shaft?  Maybe a
> replacement spring and detent?  I also have minimal flow of hot water
> through the heater core and have ordered a new heater control valve.  I
> need to flush the cooling system anyway so I will replace the valve when
> empty the radiator.
>
> Thanks,
>
> Mark
> Nashville
> Unsubscribe:
http://autox.team.net/mailman/options/mgs/[email-masked]
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---

From: "PaulHunt73" <[email-masked]>
Date: Tue, 26 Nov 2013 08:19:23 -0000

I've never had a problem with the heater when everything is working as it 
should, I get 63C/145F out of mine at an ambient of 8C/46F and that's enough 
to burn our feet.  You can't expect what is basically a 60-year old design 
to compete with modern cars.  There are no less then 10 areas in the system 
that can cause low output and all need checking.  Because of the lost motion 
in the linkage and the fact that the arc of operation of the control is much 
the same as the arc of operation of the valve, it is true that if you adjust 
the linkage to fully close the valve it doesn't move the lever its full 
distance when open.  However that is a long way from being restrictive as it 
should still lift the main part of the seal off its seat.  Before that it is 
controlling a needle valve, which gives fine control at smaller openings, 
and this is what you need to remember if contemplating a different design of 
valve, which may not have that fine control.

PaulH.

----- Original Message ----- 
> to fully open the heater valve. 

[email-masked]

---

From: "PaulHunt73" <[email-masked]>
Date: Tue, 26 Nov 2013 08:43:08 -0000

If Mark's is a Mk1 with a tin dash then probably not directly as if nothing 
else the Parts Catalogue quotes different part numbers, but comparing the 
item numbers stamped onto the control would confirm, these are of the form 
'3/nnn.

PaulH.

----- Original Message ----- 

[email-masked]