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Re[4]: MGB Heater Removal

Subject: Re[4]: MGB Heater Removal
Date: Tue, 10 Dec 96 16:53:52 PST
     Well, I thought I had to dive under the dash to disconnect the hoses 
     and such before I remove the heater box from the engine bay.  Don't I 
     have to remove the heater box to remove and service the core?
     However, I think I might try your suggestion and flush/backflush the 
     core while it's still in the heater box.  It just makes more sense; 
     that way, I can hopefully get an idea of whether or not the core has a 
     problem before contorting myself or investing unnecessary time.  I 
     sometimes have an unexplainable tendency to want to tear things down 
     all the way, even if it's not entirely needed! 
     The water valve is OK, I just removed and checked that.  After reading 
     your message below, though, I suspect that the cable may not have been 
     adjusted correctly.
     Thanks much for your help!
     Michael Lytton
     1970 MGB

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Subject: RE: Re[2]: MGB Heater Removal
Author:  "Jason F. Dutt" <> at Internet_Mail
Date:    12/10/96 1:25 PM

 Okay, now I have to ask a question.  Why are you diving under the dash?  True,
sometimes we have to rely on a bit of contortionism, but not in this 
instance...well, probably not, anyway.  You can get under there to take off the 
hoses and check for clogging in the vent lines (leaves, etc.), although I doubt 
this is the case.  
 If you are getting a strong, well, as strong as can be expected, flow of air
when you turn the fan on, the vent hoses are probably not clogged.  The problem 
with lack of heat generation is a result of a clogged heater core, a bad water 
regulator (the little brass fixture into which goes the water feed to the 
heater, and a cable.  The cable goes to your temperature selector on the dash. 
The hotter you turn the knob, the more the regulator valve opens, allowing more 
water to flow through the core.), or a clog in either the block or one of the 
hoses, these of which being the least likely.  
 First, I'd flush and backflush the core (run water through it, from a garden
hose, both ways, until it runs clear), hook it up, make sure the regulator valve
is open.  Do this manually if you have to.  The cable connecting to the dash 
control could be broken or stuck.  Turn the fan on, and see if you get warm.  If
not, there's probably some sort of mineral deposits clogging the core, at least 
partially.  I'm not sure, but this can probably be cleaned out with some sort of
 If it works, make sure the regulator works freely, as well as the cable. The
cable often seizes up to some extent.  If you have difficulty turning the knob 
on the dash, it's probably at least partially seized, therefore the valve isn't 
getting opened sufficiently.  Readjust the cable, if necessary.
 If that doesn't work...well, you'd need to ask another lister, because then I'd
be a bit stumped, and shy of saying that there's a clog in the engine block, as 
your car would probably run a bit hot if this was the case.
Hope this helps,
Sent:  Monday, December 09, 1996 6:14 PM
To:  Jason F. Dutt; 
Subject:  Re[2]: MGB Heater Removal
 > Just out of curiosity, what's wrong with your heater?  Does it leak?  Does it
just not generate heat?  
Just doesn't generate heat.  Well, it generates a very feeble amount of heat.
 > If you're doing the cooling system now, I'd definitely make sure the heater
>core is in good order.  If it's clogged up with gunk, it'll send a bunch of 
>it into the rest of your cooling system, and...well, you get the picture.
That's what I was thinking.  I'll think I'll just get a good flashlight, do a 
few stretching excercises, and dive under the dash.  Besides, how can I be an 
MG owner without a little contortion now and then? :^)
Thanks for all your replies!
Michael Lytton
1970 MGB

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