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MG MGA - heater blower removal

My heater motor works fine but although it is relatively new, it has always been really noisy in operation.

It makes a constant loud rattle / jingle type of noise which I think could be either the motor bearings or brushes. Or more likely the fan rotor is fouling on the heater units casing.

I intend to take out the motor to check it over.

My question is this:
Is it possible to remove the heater motor and fan rotor assembly from the heater unit without first removing the entire unit from the car?

Cheers

Colyn
Colyn Firth

YES !!!
Disconnect air intake hose. Remove three screws to dismount the air intake valve assembly. Loosen the collet nut in center of fan (deep well socket) to remove fan from shaft. Then remove three screws from the rear side flange to remove the motor from back without moving the box.
Barney Gaylord

Thanks Barney, I will definitely take it apart to look at it now.

If it had meant a complete removal of the entire heater unit I may well have left that job until it really couldnt be put off any longer.

For example: when the fan noise drowned out the engine noise or when sparks like from a grinding wheel began to issue from the heaters hot-air outlet!

Colyn
Colyn Firth

I keep meaning to put a heater back in my car. Been without one for the last 25 years but on my 'things to do' list
J Bray

CF, you might consider replacing the metal impeller with a plastic one. They're more efficient and give a higher output but in my case it also lead to a small additional noise due to the increased velocity of the air through the hoses and defroster slots. Bob West used to stock them.
J H Cole

I am on holiday a thousand miles away or so from the car at the moment which is why I have some spare time to think about fixing the heater blower motor.

Just wondered what size screwdriver I will need to remove the 3 screws that fix the motor into the rear of the heater unit?
It will have to be a really short/stubby driver I would have thought.
Anyone ever done this?
Colyn Firth

5/16" hex socket I think. These are originally small hex head screws #AJD1012, which is a 2BA x 3/8" long with pointed tip. It is very close to #10-32-UNF thread size, but 47 degree thread form rather than 60 degrees (like the newer Unified standard threads).
Barney Gaylord

Colyn, trying to take the motor and fan out from the rear is the better option. From experience, the fan is a real bugger to remove from the spindle...they seem to be really a tight fit, and the brass nut is there as a "reserve".
Gary Lock

I can see that me having hands like a pair of shovels isnt exactly going to help with this job!
Colyn Firth

I don't think the motor and fan assembled will come out the back without removing the heater box from the car.
Barney Gaylord

Just to make Barny's point about removal of the fan, its a friction fit on the spindle, if you use too much force you will damage it and there's little to get a good purchase on. Use plenty of WD40, patience and wiggle it off.
J H Cole

It may seem like a friction fit if it is dirty and/or rusty and hasn't been apart in 50 years. But it is supposed to be a slip fit, and the nut is a compression collet fitting. Once it is apart and cleaned up it should slip together with finger force only, and the compression nut is required to keep it from falling apart.
Barney Gaylord

Barney wrote:

> 5/16" hex socket I think. These are originally small
> hex head screws #AJD1012, which is a 2BA x 3/8" long
> with pointed tip. It is very close to #10-32-UNF
> thread size, but 47 degree thread form rather than 60
> degrees (like the newer Unified standard threads).

According to this site I found, hex size for a BA screw is 1.75 times the diameter of the screw shank:

http://www.sat.dundee.ac.uk/~psc/spanner_jaw.html

So, for a 2BA screw of 4.7mm shank diameter, it would require an 8.225mm wrench, or around a .324" wrench. Which would explain why none of my wrenches would fit those "10-32" screws in the heater.

2BAx1/2" long screws seem to be available from several suppliers. They won't have quite the right point, which won't show, but at least the head should be the right size since it appears to be part of the standard. With any luck the new screws won't have marked heads, so appearance may be close to original.
Del Rawlins

I just upgraded the heater on my E-type to a faster one from a Pontiac Fiero. Has anyone done something similar to the MGA unit? The air coming out of mine is quite poor so this is also on my "to do" list.
Neil
Neil Purves

This thread was discussed between 03/04/2012 and 09/04/2012

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