4.6is vanos bolts came loose
 

Okay this ones perplexing. We did a vanos seal rebuild on my 4.6is put the engine back together, timed just fine went to start fired right up and shut off shortly there after. Something with timing is the thought. pull of front upper timing covers to find that both bank 1 and bank 2 vanos bolts have come loose. How can this be? Has anyone run into this on the M62 engine? This is such an oddball. Would appreciate insight from those that may have experienced this situation?

You're talking about the reverse-threaded T55 Torx bolt in the center of the VANOS hub, right?

Dumb question: Did you torque them down during assembly? I also clean all the threads with brake cleaner prior to assembly.

Oh yes I am referring to the T55 Torx bolt that connects the vanos gears to to the intake cams on bank one and two. The toque specs were 81ftlbs for intake torque bolts and 92 ftlbs for exhaust sprocket bolts.

How about some locktite?

Yeah we are going to try that this (loctite) time around. Its weird I'e done 3 other M62tu vanos rebuilds and have never seen this happen.

look into this before you do use thread lock. It might not be advisable, just to be safe.

The torque for the VANOS hub to the intake cams is 89.

UPDATE: re-timed and re-torqued, got it back together and started her up. She runs like a dream and quiet. We are back in business with getting my 4.6is back to complete glory.

Glad to hear it. I had a VERY frustrating experience getting my 4.6 timed after completing the timing chain/guide service. Good to know you got it sorted out.

Was it making a noise?