When my car reaches about 200+ degrees I get this chattering noise that I can't pinpoint. It sounds like it may be coming from passenger side of the engine compartment. It's not my lifters but something else. It chatters for a maybe 1 minute and then stops and then starts again. If it's been setting over night and I get into the car and start it up it won't chatter untill it reaches 200+ degrees. I've tried the screwdriver to the ear to search out the problem but no luck. Anyone have a clue as to what this noise is? It's driving me nuts especially at drive thru's!

87 305TPI(LB9)

 

Do you have roller rockers and have you checked your valve lash lately?

 

My 305 TBI did this, it was the smog pump bearings going out. It was intermitant and ony seemed to do it at idle with a warm engine. Start the car and get down by the smog pump with an automotive stethiscope(availible at a parts stor for 15 bucks), and listen to it. You can try it first without a steth and it might be obvious. Hope that helps, it could be something else, but the reason I think you should try this is because I knew of two other thirdgens which made the exact same noise mine did, so it must be a common issue.

 

Spyder yep they're rollers and no I haven't checked them in a while. Wouldn't they chatter even when it's less than 200+ degrees? I also only here it at idle when setting still.

 

TBIWorks I've removed the Smog Pump and all emissions stuff.