Greetings, See my earlier post here: http://www.explorerforum.com/forums/showthread.php?t=331412 I use my 08 'splorer Ltd with 4.6l primarily for towing a 6000 lb (true weight) trailer. I tow about 2500 miles per summer, and drive it about 2000 miles the rest of the year. a low-use vehicle. The upper exhaust manifold bolt from the #1 cylinder is missing. https://picasaweb.google.com/lh/photo/fy8uHynVoGmuMNVM2DGlDJKVgip1PxB-Ub0Z9NWx1CQ?feat=directlink My guess is that it was there when I bought the vehicle In April of last year with 63k miles on it and it snapped off sometime since. Now I have 67k on it. And of course I hear the tick tick tick at cold start up. It goes away after 45-90 seconds depending on ambient temp. Looked at the job. Though fairly mechanically inclined, I don't want to do it. Very close quarters, I have no lift to speak of, snapping more bolts off, drilling, welding, chance of water jacket perforation. All of this adds up to me not wanting to do the job. That said, I don't want to pay a buttload (dealer) to have it done either. The only way I would consider repairing this is if I KNEW for certain what the underlying cause was and that it was fixed before going through the trouble of removing and reinstalling the manifold. No one seems to know what the root cause is. Defective manifold? Bolts? Head? poor assembly skills? etc. My main question is: What is the risk if I do nothing? Will it get worse? How much worse? Will it cause any FURTHER damage? What are the consequences of doing nothing? Thanks.