I have a 57 Oldsmobile 98 with the 371 motor. Been running fine and about a week ago I got a knock coming from the motor on the driver side. It only knocks after the motor warms up. I pulled the valve covers and fired the motor and there is NO oil going to the valves on either side. I figured it must be the oil pump. Well I put a oil guage on the motor and fired it up and its reading 35psi so I know the oil pump must be working. I am clueless now. Thanks for any help you might be able to give me. Thanks again

 

You may have a clogged oil feed hole up to the valve train which requires removing the rocker arm assembly and finding the oil hole in the cylinder head. A thin metal rod such as a heavy gauge welding wire and some degreaser would work

 

Thanks for your help. I removed the rocker and used some welding wire and I can get it to go down about 3 1/2 inches . The oild lookes to be very clean. is there a trick to get the wire to go farther down ?

 

A very small bent at the tip will help, while spinning and twisting usually gets through.
I just did a '65 400 - broken valve seals!

 

Well I think its the oil pump after all. when I start the car its shows about 35psi oil pressure and as I let the car idle after about 5mins it drops down to 10psi.. What do you think ?

 

For an Olds I think that is within range. You must determine if the knock is from deep within or is it a tap from a lifter or rocker. A rod knock can sometimes be pinpointed by pulling a plug wire one at a time and then rev the engine some. The noise will decrease or go away on the offending cylinder because there is no load on it from firing...