1987 Pontiac Firebird tapping sound

Hey all,

I have a 1987 Pontiac Firebird with the 2.8L v-6 engine and 700-R4 transmission in it. The engine has about 327K miles on it. Can't believe that it has lasted this long but it is still going. The following question may seem rediculous with the amount of miles this engine has but here goes...

I have noticed at idle that there is a rattling noise on the left side of the engine. It is not audible at any other speed other than idle, and past 1500 rpms it is all but gone. It seems the loudest at idle, at about 700 rpms and it matches engine speed. My brother has an Acura that has suffered rod knock and this sounds nothing like it. His is a definate knock that makes you want to whince when you here it. This is more quiet and many people I have talked to tell me not to worry about it or that more than likely it is not rod knock. Some have said it might be a lifter going bad. It is hard to tell if it goes away under load because about the time the converter stalls up to a load the rpms are too high to hear it anyways (about 2000-2500 rpms). I know this is an old engine and it has gone much further than many have but I would still like to know how serious something like this might be, dont want to be cruising down the highway and have it leave me stranded. Thanks for the help and I hope to hear from you soon, Thanks! Rod knock is usually loudest after engine warm up with the engine floating (point at which the throttle is held constant and the engine isn't accelerating). To figure out which rod is knocking short out of disconnect the spark plug wires one at a time. The knock may quiet down or change pitch.

Usually when lifters wear out or are defective they produce a sound simular to a ball peen hammer tapping on the cylinder head. Valve train wear or low oil pressure can cause lifter tapping also. Seeing how you managed to get a 2.8L to over 300,000mi without rebuilding is unheard of. Esp in a Pontiac Firechicken where they get ragged out by teenagers. I am sure that it is so worn out that you can turn it over by hand. Just drive till it dies cause there isn't any sense in replacing lifters in it unless your going to overhaul the whole engine. Thanks for getting back with me. I just got back from work so I am gonna try out the spark plug wire thing just to make sure. I had a local mechanic take a look at it and he seems to think it is coming from the torque converter area, and he told me to check the bolts and the flexplate to make sure its not cracked. As for the mileage, i am not sure how it has made it as far as it has as well. All I can figure is that they are all highway miles (the original owner drove often between Houston, Texas and Parsons, Kansas). When I got it I drove it from Nowata, OK to Pittsburg, Kansas which is about 100 miles one way, and I did this 3-4 times a week. Otherwise I think the engine would be scrap right now. Thanks again for the advice and take care. if its something u plan on keeping and the body is in desnt shap u can get a pretty good use motor for it something with low miles on it ....bc it wouldn`t be worth getting it a trying to fix that unlast its a corvter or flex plateCar Repair Talk's forum.