The engine is making a rattling noise that sounds like detonation at idle. I'm pretty sure it's not detonation, because the engine doesn't detonate under load. It sound like it's comming from the upper part of the engine around #4. I tried diconnecting spark wire to #4 and the sound was still there. The sound is completelyh random, but it seem like it only comes on after the engine has idled for a while. The sound is not there when the engine is cold. If i lay down under the car it can be heard as coming from the exhaust pipe. I've tried to locate the sound listening with a garden hose but it's very difficult. I hope it's not something major like something in the bottom end. If it was a bad wrist pin or something the sound should be continious and not come on and off right? It sounds serious... The heat sheald is thight atleas when i checked it on cold engine. Could it be something lying in the exhaust pipe?
Need advice!
Thanks in advance