and not sure what it is.

got a 66 200ci. quiet when cold, as it warms up get a knock in the back of the engine.

then eventually it goes away.

disconnected the plug, no effect.

got the stethoscope, definitely on the bottom back of engine, not transmission.

Any ideas? things to try and check ?

Thanks in advance

 

worn connecting rod would be my guess

 

.....

 

I don't think so. A rod bearing would knock all the time. The starved for oil lifter makes more sense.

 

Rod bearings usually knock on deceleration, my guess is a main bearing.

 

I had a rod bearing knocking in my 51 Chevy and that sucker knocked all the time. Louder on decelleration, but also on acceleration. I drove it from El Paso to Alpine at 50 mph with it knocking all the way. I was afraid to push it any faster for fear of throwing the rod. I thought I would never get there. I sold that car for $20.00

 

Little confused here. It is audible at operating tempature and then goes away? Starving lifters would happen at start up and cold temps. Noise at operating temp and then dissapear is not making much sense.

Does this happen at all rpm's? ( Assuming you're under the hood and listening, this ruleing out drive train ).

 

You need to get a stethoscope or at least a long handled screw driver and try to locate exactly where it is coming from. Obvioulsly some bearing is not getting enough oil at times. Back in the old days we would run some diesel through the engine to clean out any stoppage that may be in the channels.