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MG Midget and Sprite Technical - Heater mismatch

My blower snail has always sat too high, so it doesn't line up exactly with the heater box inlet. See photo. While I have the engine out and wait for the crankshaft to come back from the machinist, I thought I would get this right. I wondered if the heater box is too low, and should sit on some sort of plinth, but there is nothing shown in the parts list, just the foam gasket which I have. I even thought about making a new bracket to lower the blower. I'm not sure if that is less effort than making a plinth for the box. Could I have a mismatch of parts?

Les


L B Rose

Mine is the same with about 10mm offset between the two ends, it was neatly covered by the convoluted rubber sleeve between the two but that has now torn as the rubber was perished and now needs replacing.
David Billington

ETA: as usual David posted whilst I was still typing.

Could it be that the bracket (and blower) need bending slightly so the blower is slightly back and down (at back of blower). The usual concertina type connecting tube between heater box tube and blower probably disguises any usual slight misalignment from either replacement parts or original factory standard ("It's not a Rolls Royce sir").

The heater box sits on a foam seal and is screwed to the panel below, no platform.

Inside the matrix should have a foam seal wrapped around it to get the air through and not around the matrix. Also the inlet and and outlet pipes should have grommets on them to further seal the box, as I guess for insulation and to prevent engine fumes being blown into the cabin, I've used a couple of rubber grommets on the heater box face panel and they hold the pipes firmly so are a good seal.

The secret to getting the maximum air flow (and heater, if tap is open) is to have the trunking secure correctly and fully at the front of the car and the fresh air valve always fully open (unless following a VAG diesel of course).

If it don't burn your passengers toe tips then you might not be getting full heat (which can help with engine cooling in desperate times).
Nigel Atkins

You might find fitting a rear blower bracket supplied by Ashley Hinton may improve alignment. I purchased a rear bracket from one of the major suppliers and it didn’t give good alignment with the heater box.

The bracket from AH was a different profile and length, giving me a closer match to the heater box.
Philip Sellen

I have put up with this for 40 years and enough is enough! The bracket is the one that came with the car, most likely original. Yes the misalignment is almost exactly 10mm. So I have made 10mm spacers to go under the matrix box and will find some foam to fill the gap. Needs to be closed cell or it will leak. That seemed easier than making a new bracket, which because of the geometry would be tricky. I know it's not a Rolls Royce, but 10mm hardly needed a vernier gauge.

I have all the bits inside the box to seal it, and the heater is volcanic.

Les
L B Rose

mine has always been like that and the joint covered with a paper type ducting. Have owned the car since 1976 and it looks original. I found loosening the smail and heater box offered some improvement. I don't have any spacers on the heater box but can see how that would help!
Bob Beaumont

10mm, that's only 25/64", well within factory tolerance I'd have thought.

Put an engineer's crease in the bracket and you could lose 10mm and get a realignment. Or raise the n/s ride height.
Nigel Atkins

Mine's similar too but the motor won't go any lower - there's already a dip in the bulkhead to allow it to push down at the rear. I found the joining duct was flexible enough to connect it. Well I may have persuaded it a little.....
Bill Bretherton

This thread was discussed on 17/04/2021

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