hello guys this is my first time on this thread, but im a regular over at thirdgen.org, and iv gotta say im impressed with the size of this website and some of the information im finding here so iv got a question for you guys if you dont mind helping me.

iv got a 2.8 thats got a knocking type sound that sounds like it from the top of the engine under the plenum, my step dad says its a rod knocking but iv listened to some rod knocking videos on youtube and they sound nothing like it, but i had another guy say it may be an exhaust manifold gasket? im alittle depressed because i built this car from the ground up and got the engine running myself then after i get fresh paint i get a knock...it only happend after i seafoamed the car...its more noticeable now anyways, im running a stock 2.8 besides my 3.1 fuelrail, including the injectors. help?? i know iv got a donut gasket going out on my car but that shouldnt be knocking should it?

 

also forgot to say that i only hear it when the cars idleing low, like around 600-700 RPM, or when the cars decelerating, even then i only hear it when the hoods popped, going down the road i dont hear it unless my exhaust leak is muffling it

 

Excessive valve clearance due to a bad lifter, bent parts, or bad adjustment will result in a clicking sound under the valve covers. A bad bearing will sound as if a hammer was tapping against the side of the block. Hard to really tell from a distance, but the fact that the noise goes away as the engine speeds up is a good indicate of a bad lifter. A bad bearing gets noisier as the load increases. The sea foam may have loosened up some harmless sludge and it worked its way into the lifters. Mechanic in a can is not the way to fix engines.

 

so should i pull the covers and have a look? also i was told that it may be a bad exhaust manifold gasket, rod knocking, or loose torque converter bolts, what should i do about a bad lifter? iv never worked on this engine, but i did put together a 350 but asfar as knowing what to do when there bad im lost.

 

Get a 3 ft length of hose, put one end to your ear and move the other end against the engine and try to isolate the noise source.

 

i tried that with a screw driver, its beneth the center of the plenum, between cylinders 1 and 3, but on the top of the engine around the injectors.