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MG MGB Technical - High pitch whistle under driver dash when sitting

I went in my garage last night and heard a small high pitch whistle. I found it coming from under the driver dash and when I disconnected the battery it stopped. My 1974 mgb roadster has been parked about a week. Any ideas what could be causing this? Thank you as always, George
GH Higginson

My quick thoughts until other more knowledgeable posters come along.

Radio left on off station, electric motor – windscreen washer, blower motor, electric cooling fan(?) - an auxiliary fitted item(?), something very obvious I can’t think of or don’t know about on USA cars.

Good luck.
Nigel Atkins

Air Leak on the induction side somewhere. Check the manifold and the carb nuts.
Allan Reeling

Did that model year have either seat belt warning buzzers or door open buzzers?

Charley
C R Huff

Or key left in the ignition buzzer?

Charley
C R Huff

This year (1974) has seat belt buzzer and maybe ignition buzzer. Neither work on this car. As for vacuum leaks, this occurred with car not driven for a week. George
GH Higginson

The North American 1974 had both the 'key in door open' buzzer and the sequential seat belt system, but they both used the same buzzer. That circuit has an 'always on' power supply off a brown wire via a 500mA fuse and a brown/purple wire. Find that fuse and disconnect it and see what happens. Bear in mind you probably won't be able to start the ar with that fuse unless you bypass the part that isolates the starter relay.
paulh4

GH, Maybe they don't work as they should, but has the buzzer been removed?

Charley
C R Huff

I’ve found the whistle. Just above the radio is some kind of control box. The wire plug in back was loose and poor connection caused the noise. Now no more noise although curious about what that control box is. As always many thanks, George
GH Higginson

Does it have a plug with 12 pins? If so that's the controller for the sequential seat belt system as mentioned.
paulh4

This thread was discussed between 11/03/2018 and 21/03/2018

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