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Author Topic: '76 MGB fan motor  (Read 5853 times)

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march2010

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'76 MGB fan motor
« on: March 05, 2010, 12:41:00 AM »
When I line up to ventilate or defrost the fan puts out about as much air as a good cough. With the top up and in the rain I have to continually wipe the inside of the windscreen with a rag just to be able to see to drive.  Not very safety conscious.   Anybody know of a more powerful fan motor that can be installed in a standard 76 MGB heater?

George.  
« Last Edit: March 05, 2010, 12:56:50 AM by amgba »

Art

  • chfwrench
  • AMGBA Club Tech Staff
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  • Posts: 260
  • Memberhsip Number (if known):: 91-10014
  • MG information: '73 red B roadster
Re: '76 MGB fan motor
« Reply #1 on: March 08, 2010, 11:44:24 AM »
Hi George,

Before buying anything, I would first pull the fan motor and inspect the fan itself for dirt or damage as well as the heater box and core for dirt, leaves and gasket deterioration that might restrict airflow.  It would also be good to check the lower ducts and intakes for blockage and the louvres for dirt and rust that would keep them from fully openning.  Any of the above would give the symptoms you describe and with the potential of some 34 years of leaves, dust and road grime collecting, it is entirely possible you have a partial blockage.  No improved motor or fan would help with addressing that.

The fan motor is fairly easy to remove.  With only 3 to 6 screws securing it, you can just pull it out and look at the fan as well as the heater housing and one side of the heater core.  The fan should be a plastic unit, so it is more subject to breakage either at the blades (if enough are cracked or missing, your airflow goes south) and even the hub, which in the extreme would separate it from the motor shaft, rendering it useless.  If it has the older metal fan, dirt and rust accumulation are more to be expected.

Checking the intakes, ducts and louvres (and full heater core) is more involved and cleaning in place is at best messy, but start with the motor and fan, as you might find your problem there.

I know I saw an aftermarket fan kit somewhere with a better squirrel fan and multi-speed motor and switch, but was not able to find it now.  Checking the usual suspects, Victoria British only offers the motor (one type for all) with the fan available as part of a full heater unit.  Moss is offering 2 replacement motors (OEM style early and late), but only one fan (the later plastic unit, which would be correct for your year).  If I come across the aftermarket kit, I'll passs it along or if anyone else knows of it, please post-up.

I have also seen adaptations of fan motors from older American cars, particularly from 70's and 80's GM models, even going so far as using the multi-speed switches and resistors, but they require some work to fit and do not look original once done.   

I hope this helps you.  Let me know what you find out here or e-mail me at chfwrench@aol.com.  I will answer you as best I can and post it here later.  Good luck.

Art
Art Isaacs
AMGBA Tech Staff
chfwrench@aol.com

march2010

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  • Posts: 4
Re: '76 MGB fan motor
« Reply #2 on: March 09, 2010, 11:34:02 PM »
Thanks, Art.  This car was recently restored right down to the bone by Kenny Middleton in North Charleston for the owner who lived in Summerville , S.C.  He passed on a stack of photos taken through the restoration process and a wad of receipts for all the parts he used.  I have to believe if he went to all the trouble to document everything like that the ventilation system was thoroughly checked out.  I'm probably expecting too much from the fan cause American cars have such powerful three-four speed blowers.  As to keeping with traditional stock parts I'm not too concerned.  If an aftermarket fan does the trick it's going in there.  I'll try your suggestion to dismantle, inspect and clean for starters and see where that takes me.  Thanks again Art.

George. 

Art

  • chfwrench
  • AMGBA Club Tech Staff
  • ****
  • Posts: 260
  • Memberhsip Number (if known):: 91-10014
  • MG information: '73 red B roadster
Re: '76 MGB fan motor
« Reply #3 on: March 24, 2010, 12:23:00 PM »
Hi George,

I think I found it.  I now have a copy of an "Enjoying MG" magazine from the UK that has a whole article on the fans and motors for the Smiths heaters as in the MGB. 

The upgraded fans are not a bolt-in.  It requires a fair amount of adapting because of a larger fan diameter and different motor.

I'll try to scan and post it here, but if you send me your e-mail address, I can send a scanned copy to you directly.

My e-mail is chfwrench@aol.com.

Art
Art Isaacs
AMGBA Tech Staff
chfwrench@aol.com


 

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