I see that the argument that I started probably 15+ years ago, still goes on, about the torque spec for the ALH cam sprocket. I know I made some well known 'gurus' upset to claim 33 ft lbs on a cam sprocket was blatantly wrong, and as simply as I can put it, the claims of 'damaging the cam, sprocket or cam sprocket bolt by 'over-tightening',' is BUNK!
And I think I can speak with authority, as I know of nobody else who has built as many or of the quality I make cylinder heads for the TDI's.
Now, I see the error is being retro'ed to the AHU timing belt procedure. The AHU sprocket bolt, in several different manuals calls out a 54 ft lb torque for the cam sprocket bolt. The next cam, the ALH, is virtually IDENTICAL, and the book says 33 ft lb torque spec. The next generation, although the cam originally is cast steel, the connection id virtually identical, the sprocket material is the same and the torque for the PD motors went UP to 74 ft lbs.
In all the business I have done rebuilding TDI cylinder heads, the most avoidable is the slipping of a sprocket on an ALH, and now I find, the AHU is included with this insufficient tightening of the cam sprocket bolt. There are years that up to 6% of my cylinder head business is DIRECTLY ATTRIBUTABLE to this completely avoidable error.
Just to prove the point about damaging the cam sprocket, bolt or the cam from over-torque, I took some scrap parts, clamped the cam into a vice and tightened the sprocket bolt onto the sprocket with150ft lbs torque. I was afraid I might snap the bolt, so I stopped there. After returning from my usual Sunday morning, I pulled the sprocket bolt and used the sprocket buster to remove the sprocket and although I won't deny, it took a lot of effort and it came off with a BANG!, I could find no issues or 'damage'.
I continue to get the occasional 'spun cam sprocket', and if I could get a consensus to STOP WITH THE 33 FT LBS, I'd do it. Does it bring me business? You betcha. I'd rather not see it.
You tell me... with two of the engines; ALH and AHU, there is nearly a 20 ft lbs discrepancy in torque load. Add yet another 20 ft lbs, that's what the PD engines use. You have to use some common sense, WHY would the ALH be so different? IT'S NOT! Good Grief, it's a 14mm bolt! If it only needed 33 ft lbs, Shouldn't VAG have used a 10mm bolt??
Save yourself the heartache and expense. I use a torque spec of 45 ft lbs. And only did that to avoid the people freaking out. It should be the same as the AHU... 54 ft lbs. Do that for the AHU and ALH cam sprocket and you will not be sorry.
Frank's VW TDI's