So I just did a lot of work on my civic. I replaced my head gasket, which I thought was blown, and went ahead and replaced my timing belt, water pump, and all drive belts. I even did a mild port and polish on my head when I had it off and cleaned all of the carbon build up from the cylinders. I did all of this myself; this was also the first time I did something this big. Well after I finished, the car seemed to be running fine, however I think my ignition timing was off. Other than that, I couldnt tell anything was wrong. Well, I was going to get a timing light to check the ignition timing, and do another compression test but I never had the chance to because one afternoon, my engine just died. I just left my house and was basically coasting to a stop and my engine just shut off. After messing with it for almost 3 hrs on the side of the road, I finally was able to have my dad tow it back to the house. After messing with it some more (checked ignition coil) I decided to check the timing marks on the cam and crankshaft. Thats when I noticed that the cam was almost 90 degrees off. I thought the timing belt slipped so I took it back off and was about to rotate the cam back when I noticed the camshaft bolt was loose. I could unscrew it by hand it was so loose. I never took the cam gear off of the cam while I was working on it. In fact, I cant remember ever even touching that bolt, so I dont know how it came loose. Then on closer inspection, I noticed that the woodruff key seemed to be sheered off and jammed in between the gear and cam crooked. Dont worry, It gets worse. After trying to get the gear off the cam, I end up breaking one of the lobes off the camshaft. I was finally able to get the gear off using a pulley remover. The key was indeed sheered in half, and it looked like the gear was still rotating around the cam, while the cam wasnt moving with it. However, the cam was moving atleast some because the distributer rotor was moving. I ended up buying a complete rebuilt cylinder head to replace mine, because I didnt know if I bent some valves, or screwed something else up. I am currently waiting for it to arrive.

I dont understand what would of caused that bolt to come loose. I thought that maybe something jammed up the camshaft, broke the lobe off and broke the bolt loose, but I inspected the cam before I started to mess it, and didnt see anything amiss. Im sure I would of noticed a broken lobe. Any advice on what happened? Would the wrong ignition timing have caused this?

Maybe the bolt was loose before hand and it just went, maybe it happened when you rotated the belt to make sure it was on and adjusted correctly; making sure the tensioner tightened the belt enough (you did do this right?). But ignition timing definently wouldn't do that. Honestly I'm not really sure what could have caused that to happen, but I have seen it once before. A guy I know had his cam gear just spin along with the belt, but it didn't move the camshaft at all. Wish I had a better answer for you.

I thought about that, and thats the only thing that I can come up with that would cause that, but it didnt break down until like a week after I finished working on it. I would of thought that if I accidently loosened the bolt while tightening the timing belt, it would of messed up soon after starting the car. And yes, I did properly adjust the tension. Thanks for the reply.

I forgot to ask earlier, can I reuse the head gasket that is currently on the car or should I replace it. Its only like a week or so old.

if its already torqued down, you need to replace it

if you had loosened the bolt while you were adjusting it, it could have happened right away, or it could never have happened at all.. I've seen it go both ways... made this mistake on my first engine... replaced water pump, put it all back together, didn't do anything wierd, replaced the cam sprocket like 4 months later, and I could pull the bolt out with my hand, but it never hurt anything.