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MG MGB Technical - Temp Gauge Chatter/Bounce

When starting my 72B for the first time during the day, when it is well cooled down; the temp gauge needle bounces very rapidly while setting on the cold mark of gauge. As the engine warms, and the needle moves up the gauge towards N, the bouncing slows.

It is not bouncing all over the gauge, it is more like shaking rapidly in place, not moving more than the width of the needle. Like a very nervous needle.

Once even 1/2 way towards N, bounce/shake is calm; and needle is steady all day if engine is warm.

I've cleaned contact at engine block, cleaned sending unit at block. Is this a contact issue elsewhere or a sticky sending unit? Concerns?
R.W Anderson

R.W. - I would check the voltage stabilizer, particularly that it is properly grounded via the mounting screw. If this is not the culprit, the next check would be the sending unit and the connection to it. Cheers - Dave
David DuBois

Sounds more like a mechanical issue to me, the electric gauges are thermal and very slow acting, witness how long they take to get to zero when switching off the ignition as well as rise between turning the ignition but not starting (warm engine). Also the stabiliser feeds the fuel gauge as well, so even if it were possible for chattering to be from an electrical cause it would affect both gauges.
PaulH Solihull

Fuel gauge doesn't chatter, just temp and only when cold, with chatternig decreasing as temp rises.
R.W Anderson

My 75 roadster has been doing this for the past ten years, so it is nothing to be concerned about.

I am using a solid state voltage regulator so that rules out an electrical cause.

Since the gauge reads steadily and accurately once at operating temperature I've left well enough alone.
Steven 67GT

I'll be taking Steve 67GT's advise, and agree that as it eventually settles down, I may as well leave it alone. I was just concerned for whether or not the rapid chattering was not good for the gauge.

thanks.
R.W Anderson

It won't be, as it probably involves components rattling from one end of some free play to the other, which could well be from mechanical wear, and will tend to increase the wear. However it's not an indication of a problem anywhere else on the car which is the important thing.
PaulH Solihull

This thread was discussed between 06/07/2011 and 08/07/2011

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