MGB: Rattling between 2000-3000 RPM

Hey all...
Its been forever since I've posted..which I suppose is a GOOD thing for my MG's sake! I have noticed a rattle..between 2000-3000 or so RPM...it is not effected by whether the car is in gear or neutral. There is no change in performance, and the car runs just fine. Any ideas? It SOUNDS like a loose bolt or a speedo cable going bad...but the tach is electronic right? ANYTHING anyone can pass along as to wear to look first would be much appreciated.

Chris

What gas are you using?? How far is your timing advanced?? Is it maybe 'pinging'???

Where is the noise? You said it sounds like, but not where it sounds like that.

Sorry...
Should have been more clear...the sound is coming from under the hood, doesn't sound like transmission/driveline..etc. I don't think its pinging from gas, it has the usual 92 octane in it, and it doesn't seem to be effected by hard acceleration. It goes away over 300 RPM, and doesn't show up until 2000. Its a mystery Charlie Brown.

Chris

I'll leave that to smarter guys than me! I still bet it is pining!!

Have someone sit behind the wheel and rev it up while you look under the hood.

I've got an annoying rattle like that. It's a brake line hitting against the firewall that needs to be secured. It's a rapid rat-a-tatta-tat, and it drives me nuts. Sounds a lot louder than you'd think.

I got one of those, too. I'm pretty sure it's a brake line or fuel line coming across in front of the heater box. Loud. Annoying.

Check the exhaust mounts - I had a rattle right around 3K, turned out to be the bracket at the bottom of the head pipe.

Cut and split a little piece of fuel line hose or something like it, slip it over the line and slide it down to the rattle point. That'll stop it.

I found that one, Brian. It was an extra clamp that wasn't hooked up. This rattle is coming from the engine compartment.

You might look into the bolts holding on the fan. On my 67 with the three blade fan the four rubber grommits have been known to perish quicker than usual and even a very slight looseness there will make a very noticeable rattle. It is 7/16th, if you can turn it without too much work you may have found the problem. You can get away with tightening for quite a while before replacing.
Carkl

Don't know what model your car is (or what carb setup) but, if you have the ZS carb it could be coming from the air cleaner area - maybe the flapper valve at the hot air pipe...