I've been through the bad idler pulley thing too. Does your car have A/C? I'm pretty sure it does being a 78 2+2. I think it was standard on those. Shoot a little WD40 on the bearing area of the idler pulley. It won't solve the problem but it will stop the noise for a while if the pulley is the cause but it will come back. That way you'll know if that's what needs to be replaced.

Hi Guys,

Unfortunately the sound disappeared this weekend and I was not able to record the sound. This morning on my way to work it came back while driving and by the time I got to work it was gone again. Anyway, I'm going to spray a little WD40 on fan clutch and see if it disappears for a while as suggested.

Stephen,

Yes, It does have air conditioning and I was thinking the same. I'll take the belt off and see if that does the trick.

Thanks, guys I'll let you know what happens.

Rick

Good posting .. I have a similar "Rattle" noise and I can't tell if it's from the Engine or Tranny/Clutch. It's been noticeable sometimes louder than other times in warmer/hotter days. I would appreciate any insight or suggestions.

The symptons are:

1) When driving and running in 3rd or 4th gear in 2.2 - 2.5k rpm range there is a noticeable rattle or "clanking type" noise. Sounds like metal-to-metal rattling.

2) When idling in Neutral, Clutch Depressed - No Noise.

3) When idling in Neutral, Clutch Released - Same Rattle or "clanking type" noise.

Given symptons #2 & #3, I thought it's my be the clutch linkage? Would it be a throughout bearing?

Any insight or suggestions is appreciated. Many thank...

I forgot to mention in my post above. I own a 1973 - 240z ... Thanks...