My t/a started to make this buzzing sound.It sounds like it's coming around firewall or dash.It's pretty noisy and you can hear it from the inside or outside.Sometimes it stops when i'm driving but at the idle it's usually there.From what i see it could be my rpm gauge cable or something.The gauge is jumping from time to time.It started to do that after the extreme colds one week ago.1 month ago it was making the similar noise but then i found out that my steeering fluid level was low.I've filled it and the sound was gone.But the sound is really similar.What you guys think?Any info will be appreciated.

 

Tongi,

The Tachometer (RPM gauge) is completely electrical. There is no Bowden cable that drives the instrument. The noise is likely from another source.

If you have an automatic trans, the noise could be from the pump/oil pressure regulator. These were prone to making noises at a low RPM on the older (pre-1986) models. This normally happens when the transmission oil is hot, not cold, but if you have a very low idle RPM, it could be a problem.

 

Vader

Thanks for the reply.The sound is always there even when it's cold.When it warms up it sometimes goes away.Specially when i press the gas on idle and raise the rpm or when i'm driving.When the sound is there the rpm gauge jumps.When it's gone it works normally.The cars idle is normal around 800-900 rpm when the engine is hot.When it's cold it idles around 2000, 2-3 minutes later drops to 1500 and then when it warms up goes down to normal rpm range.Today when i started the car the sound was there for 30 sec. or so and it went away after and never did it.But today weather is warm here.(Last week it was around -40)I wonder if it has something to do with the cold.