Buzzing noise?

[roverman]

1999, Rover SE
I thought it was the air compressor going off more and more frequently indicating that my air susp. was starting to fail. Took a while for me to put two and two together but when it sits a while it never loses air, so it probably isn't the air comp. Is there an alternate source for the buzzing? It sounds very much like an air compressor. Is there something similar that pressurizes the brakes for instance? Seems often at a stop light the sound turns off when I take my foot off the brake. (but it also goes on and off when I'm not braking)
Thanks for any advice.
Roverman

 

[joey]

I would check the fuel pump (see if you hear the noise in the boot/trunk), could also be something in the fan blades if noisy while the heat/a/c is on.

 

[roverman]

No, it seems to becoming from somewhere (near my feet)? in the engine compartment. Definitely not in the rear. It is definitely an "on purpose" noise, meaning not a broken anything. It sounds very similar to the air compressor in my old county, but louder and not behind me. I can't help but think it's connected to the braking system, which I know nothing about.
Thanks for your speedy reply...you are great!
Roverman

 

[joey]

Does it do this even when parked, or just when moving?

If parked, pop the hood/bonnet and listen for the issue. If only when moving, then I would think ABS pump or similar.

 

[roverman]

Hmmm...I started it up and it did it upon start a couple of times and then ceased for 5 minutes or so. Pressed brakes a bunch and revved engine couldn't get it to repeat while parked. The engine compartment was too noisy to pinpoint. I can hear it much clearer sitting in the driver's seat than with my head under the hood.

 

[joey]

When you hear this buzzing noise, do you notice anything else happening. Tach jumping, radio static, lights dim, power steering feel tight etc...

Anything at all?

 

[roverman]

No, nothing else out of the ordinary at all.

 

[joey]

It may very well be the Air compressor (I don't have nor have I worked on a RR), but it sounds like the compressor may be building a charge back up... could be a leak from a distribution block to the compressor, which would not effect the air bags...

Not sure, just guessing, since I can't hear the noise, nor can I go from memory.

 

[roverman]

To go back full circle to the fuel pump:
My check engine light has been on. I had the dealer check it and they told me that the maf is bad. The only symptom has been a slight stuttering when starting up at a light. It hasn't really bothered me. Now you've got me thinking that maybe that is a fuel pump symptom?

 

[joey]

If the dealer said the MAF is bad, have you tried cleaning it with some non-residue contact cleaner?

Remove the MAF, spray contact cleaner into it from the air filter side. Also clean the contacts for the plug.

Let dry for 15 minutes or so, just in case some cleaner pooled up.

Reinstall and check.