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MG MGB Technical - Radiator diaphram seal

I purchased a radiator diaphram seal from Moss today but when I fitted it I couldn't get the bonnet to shut.

The channel that the new seal fitted in to had the remains of an old seal which I removed. Also, the bonnet has sound insulation fitted and there just didn't seem to be any space between the diaphram channel and insulation for the new seal, so I've left the seal off at present. Anyone else had a similar experience? My car is a 64 Mk1
Kevin
K M Sheahan

How much foes the seal project above the diaphragm channel? Should be no more than 1/2" (haven't got mine handy to check) and be a lip and so should compress easily to form a good seal.

How thick is your bonnet insulation? That should only be 1/4" or so.

Have you taken the seal out again and check that the bonnet still shuts? Could be coincidence, the bonnet saying "Well if the radiator can have a new seal I want a new latch".
Paul Hunt 2

Paul,
The bonnet shuts OK without the seal in (although see below!). Also with bonnet down and looking up towards the diaphram channel with a torch through the grill the insulation looks to be making a good seal. Indeed, when I looked at the insulation there is an indentation line corresponding to the channel.

I'll check the insulation thickness.

I have had a problem with the latch I think. On a couple of occasions the bonnet has popped free, can the latch be adjusted, or do I need to replace the catch spring?
Many thanks
Kevin
K M Sheahan

Try slackening the diaphragm bolts and pushing the whole thing down a bit. If the channel on its own is making an indentation in the bonnet insulation either it is too high, the bonnet too low, or the insulation too thick.

Bonnet popping up can be caused by wear, which is usually on the pin. However if the radiator diaphragm is fouling the bonnet maybe it isn't fully latching, as evidenced by not being able to latch it at all when the rubber seal is fitted. You can unscrew the pin about 1/4-1/2 turn which should help. As well as working on a previously unused part of the pin it will also raise the bonnet a fraction! However before doing that make sure the release cable and latch plate are free and the latch plate is fully returning.
Paul Hunt 2

Thanks Paul, I've adjusted the bonnet pin. I'll investigate the radiator diaphram further this weekend.
Regards
Kevin
K M Sheahan

This thread was discussed between 16/02/2008 and 18/02/2008

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