I think the other guys may be right about checking your valves. It makes sense that you wouldn't hear it any other time than when you're sitting still.

 

Ok thanks.

 

I can't hear most of the noises my truck makes unless I'm sitting still. If I'm moving I hear the fan howling (sometimes), the exhaust and the stereo. Oh, and the wind leaking through my vent windows.



Which brings me to another noise posibility: the bearing on one of the idler pulleys- either a/c or power steering, or possibly even the alternator, water pump or fan clutch.

 

94 toyota p/u 4 cyl 22re Auto
HELP!
So I replaced all the belts, and tension may be a contributing factor but heres whats up:
Ticking/Rattle Noise (honest more like a Paint-Can Rattle) gets louder when A/C Compressor is turned on. Checked and noise is NOT coming from Compressor/Clutch. The noise seems to come from the Power Steering Pump-area. Fluid level is okay, but I did have a high pressure P/S hose leak and repair 3 years ago and it's been fine since the fix. So when the engine is under load its not getting louder, only when the A/C comressor kicks on does the noise in the P/S pump area increase.

Any help is much appreciated!

 

Wow, Okay. I found the issue, and thankfully it was a classic case of "if you want it done right, do it yourself!"
I broke down far from home and had a unknown shop replace the Alternator. The rattle was their incompetence, as I noticed after more inspection that they didn't bolt down the alternator thru-bolt and nut. I rev-ed the TB and return to idle showed me how the Alt just seemed to move, just a little. Problem solved. Got underneath and torqued it down. I was really thinking that it was the PS pump, idler pulley bearing, or even the breakdown may have stressed the timing chain/guides.

Emergency averted.