My wifes car started to make a knocking/rattling sound. I will not do it untill the car has be running for about 5 minutes and warms up. The car was low on oil when this started. The motor still has all its power and runs fine except for the loud fast knocking sound. what all could this be? I think i should start looking at the pushrods and rockers. Any help is appricated. thanks

 

valvetrain noise is more of a rattle or tick, most times knocking would be a connecting rod. can you post a recording of it?

 

How low are we talking about? If the oil level went dangerously low, you could have trashed the rod and/or main bearings. "Rod knock" tends to be more evident once the engine warms up, when bearing tolerances change, and the oil thins out. Bad lifters generally make noise upon start up, which makes me suspect the lower end. What is your oil pressure gauge reading?

 

http://www.youtube.com/watch?v=m0zIjTx4QZ0

heres a video after the car has warmed up for about 5 minutes. oil pressuure is at 80 when its cold and then goes to 40-60 depending on the rpm's. the car has always idled at 1500, thats why its high in the video.

 

ok i went and got a listening stethoscope and to me is sounds like its coming from the front passenger valve cover area. I put the scope on both valve covers and the drivers side just sounds like the lifters and rockers. passenger side sound like lifters and rockers untill you get to the front of the valve cover, then it gets the knocking sound. I also put the scope all over the oil pan and it was just a faint knocking coming from it. I did notice that the oil pan gasket was leaking, guess thats where all the oil went.

 

That sounds like valvetrain to me, as opposed to a rod knock.
It has more of that hollow "sewing machine" sound.

 

fixing to go get some gaskets and pull the covers off.