hey guys im looking to buy an engine in craigslist. the engine will be out of a car but open with no head on it.

is there a way to test the engine while it is in this state for rod knock before I buy it?
just in case the owner doesn't know it had knock or if he is lying.

 

pull the pan off and inspect the rods for excess play. That, or youll have to remove the rod caps to check all the bearings for damage

 

If there is any question, don't buy or it would have to be really cheap(free). Pull the pan off, look for sloppy rod to crank play. Check the head side for a thick ridge that isn't carbon build up, examine piston tops carefully for damage.
Regards
Dave

 

If the rod was bent due to damage, this would show up on a compression test as low compression, usually an adjacent pair (IE 3-4 or 2-3 or 1-2). This the easiest test to perform.

There are other means of checking the rod-to-crank journal clearance but that is the least invasive method. Anything else involves removing the spark plugs our oil pain to manually inspect the bearing wear.