I just bought a 1992 pickup with a 22R motor in it and it has a knock in it from 1100 - 1600 RPM's and then it goes away when motor warms up completely. what could it be? i found it is coming from back of motor close to tranny. does anyone think it could be a piston skirt broke or what please give me some ideas

 

Someone's knocking in there? Open it up and see who it is

Maybe valve clearances are off, and they get closer as the engine warms up, causing the noise to stop? Hard to just spit out a correct answer for a noise

 

If you are sure its coming from back of motor, i assume, bottom end, and i am going to say rear main bearing. If you pull the oil pan and the crank, you'll be able to check it out. Before you tear out the bottom end, do check the valve clearances. They shouldnt be any more than .001" off spec. if they are not, then thats not the noise your looking for. Its most likely a rod bearing or main bearing. At this point 2 choices. Run it until it dies and then your looking at a new motor most likely, or repair it now, cost only being about 300 bucks max. And you can do it yourself. Let me know if i was on the right track?