Timing Chain bunching/skipping a link?

[Zak Wilson]

I'm replacing the chain guides on my variocam actuators and I'm afraid I may have created a bigger problem. 

 

I had already removed the tensioner on bank 2 before re-timing bank 1 to test it. I was going to replace it before doing the timing procedure on bank 1, but had a difficult time getting it back in, so I decided to proceed since it theoretically doesn't affect the timing of bank 1. Now I finally got the bank 2 tensioner in and am timing bank 2, but during the procedure the chain pulled the slotted gear off the end of the bank 2 exhaust cam. When I put the crank in cyl4 TDC everything looked properly timed so I thought I was in the clear, but now that the gear got pulled off the cam I'm not so sure. So now I'm wondering:

 

1) How likely is it that I bunched the chain?

2) If I did bunch the chain (or skipped a link) do I need to split the case or should I be able to fix this by simply rotating the crank and fenagling the chain on the bank 2 slotted gear? 

[JFP in PA]

Welcome to RennTech 

 

I would say it is unlikely you had the chain bunched, but you now need to be very careful and recheck everything according to the service manual procedures. Most people do not realize you and actually damage the valve train rotating these engines by hand if the timing is far enough off.

[Zak Wilson]

Thanks!

 

My plan is to remove the tensioner again and re-seat the exhaust cam timing sprocket then re-attempt the procedure on bank 2. I hadn't even thought of valve train damage. That would be no bueno. 

[JFP in PA]

Whatever else you do, NEVER rotate one of these engines backwards, even by hand.  You will have problems if you do........

[Silver_TT]

Why?  I understand that you never want to rotate the engine even if it is slightly out of time but if everything is in time why can’t to be rotated backward?  Thanks for the info

[JFP in PA]

2 hours ago, Silver_TT said:

Why?  I understand that you never want to rotate the engine even if it is slightly out of time but if everything is in time why can’t to be rotated backward?  Thanks for the info

 

When rotating by hand, the hydraulic tensioners and Vario Cam units are relaxed enough to allow the pistons to contact the exhaust valves just enough to bend them if the engine is rotated in the backwards from normal rotation direction. Once that happens, the heads need to come off.