Ill skip the full back story and just give the pertinent details. A couple of months ago I swapped a low mileage (45,000) salvage yard motor into my 200K+ V70R. I put new seals in it and transferred some stuff from the old, to the newer motor. Upon start up there was a noticeable wobble in the exhaust VVT. Soo, I changed this out with the one from my original motor. This one had a little wobble too but, from what I can tell from lurking on the sites, a little wobble may be normal. Once completed and fired up the motor ran great, smooth as can be. After a few days of driving I noticed a oil leak that turned into a major leak within another day or two. Checked the front main and it was destroyed. The inner lip was completely torn away from the outer ring. Seal was a Felpro, don't know what caused this(has anyone seen this before?). Old stock maybe, I don't know. Installed a new seal and started driving to work on a daily basis. A month or so later I'm driving to work in the morning, the car is running great. Crisp, responsive, feeling good. Soo, I decide to wick it up a little and make sure I have the bugs worked out. At about 110 the car shuts off, no noise just the dash lights come on and I coast to a stop. I have my scanner in the back so I check it. 3000, 0342, a misfire code and something else, coolant or something. Anyway it wont start, so AAA takes me home. With the 3000 and 0342 pointing at the cam sensor, I swap sensors from my other motor. Nothing, same codes. Anyway after more investigation I find the broken camshaft. Ive not heard of this being an issue, has anyone else? Could the VVT wobble be to blame? Is this friggin car cursed or what? I have 2 exhaust valves bent in cylinder #3, haven't removed the head yet to determine full damage.

 

definitely cursed. I think this is the first post I've read with a report of a broken cam. I'll be doing some research on rituals to cure the curse while you're working on the rebuild. Good luck and post up the results. :-)

 

I would say that the problem was over-torquing the large bolt holding the bolt to the cam. The maximum twist would be right against the bolt head. I've never seen this before but my guess is that it cracked at that point.

The wobble must have been in the VVT unit as there is no way to wobble the end of the camshaft due to the bearing at the end holding it square.

 

I agree on the wobble, and I will be extra careful when torqueing the bolt this time. I wasn't able to do much this week, hopefully have it disassembled in a week or so.

 

I tighten these by feel rather than the torque wrench. This method is partially due to the proximity of the bolt plus I find that putting an extension on a 3/8 ratchet gives enough torque to break it loose. I use just a bit less torque to tighten it down.

I cannot think of anything else that would break the cam unless it was dropped somewhere along the line.

 

Update:
Pulled the head, looks like pistons 3 and 5 had some contact. #3 exhaust valves are definitely bent, not sure yet on #5. I have another head, I will probably just change out both 3&5 to be safe. Made the mistake of not marking the lifters, going to have to check all clearances for proper fit.
Question: Is there a way to identify valve stem dia. prior to removing, 6mm vs 7mm?

 

I strongly recommend that you send this head to a machine shop where they can set the proper valve clearance. Since you mixed up the lifters, I'm concerned that you need to replace them all since the wear patterns won't match the cam.

But, at a minimum, get this done with a machine shop.