Start at the left head (driver's side if LHD), be sure to mark the cam sprocket and chain with paint, so everything can be lined up upon assembly. Once the paint is dry, loosen the cam sprocket bolt, then unbolt the tensioner on the right side of the block. Using a mallet tap the cam sprocket till it comes free of the cam shaft. I just wired the chain to the closest fixed object to hold it upward so nothing slipped internally. I remove the lower pin first, then work on the upper pin, when the upper pin is about to come free, just grab ahold of the guide, soon as the pin comes free you'll be able to slide the old guide out. Replace both guides, put the sprocket back in the chain and place it on the cam shaft. As long as the marks you painted line up, everything should be fine as the cam shaft has a woodruff key and can only go on one way. The other side you don't need to remove the cam sprocket. Once the guides are in and the tensioner is bolted in place tighten the cam bolt to 100nm (I think).
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.