85 - Noise & Service light - HELP

I'm hearing a low "exhaust-like" knocking/clacking in the engine occassionally, accompanied by the "Service Engine Soon" light. It's at a low idle when the engine gets warm. And when the car is fully in motion on the street or highway I can see the "Service Engine Soon" light go on and off periodically. There's no temp gauge and the "Overheating" light works, but never goes on.

Pretty consistant regardless of the car's idle or acceleration.

Help!

Check the EGR (exhaust gas recirculation) valve. It may be stuck open. It is mounted on the intake manifold on a V6. If you've never replaced it, it's probably time and they are not all that expensive.

Check the EGR (exhaust gas recirculation) valve. It may be stuck open. It is mounted on the intake manifold on a V6. If you've never replaced it, it's probably time and they are not all that expensive.

Finally got the EGR valve in the mail - found an AC Delco on ebay for $28. Like you said - at least it's replaced now, but I think the "exhaust-like" rasping noise is coming from the Smog Pump. Do you, or anybody else out there, know anything that can be "zeroed in on" when it comes to the Smog Pump?