Join Date: Jun 2008
Location: SLC, UT
Car Year: 2001
Car Model: Forester
Feedback Score: 0 reviews
After reading the article I gave keywords for above, the whole torque procedure made more sense. According to the author, Torque To Yield actually takes special equipment, but Torque To Angle allows you to predictably apply a clamping force based on advancing the bolt a certain number of threads beyond a given torque. The low starting torque coupled with oiled threads and washers means that you're not fighting friction so the starting torque should be accurate.*
I've built a Ford 289, a number of Type I VW engines, and a Type IV VW engine. I think the Ford engineers figured you're clamping an iron head to an iron block so you just apply a s***load of torque and call it a day. The VW engines were low compression and air cooled, so you didn't have to worry about blowing the head off or leaking combustion gases into the water jacket. Back in those days engines were higher maintenance and weren't expected to last as long as we expect today; a VW engine would be getting a rebuild at about 1/2 the minimum life we expect from a modern Subaru, Honda, or Toyota. I haven't done any major engine work for about 10 years, though, so I feel like a bit of a newbie.
Based on what I read... keeping in mind I didn't taken a fastener engineering course... I suspect reusing the head bolts one time would probably be okay, but for the price of the bolts it's cheap insurance if the engine goes 100k or more miles on this head gasket replacement. I appreciate the nudges in the right direction!
Paul in SLC
1988 Vanagon... soon to be Subie powered
*That synopsis is for the benefit of those who are trying to understand the rationale for replacing the bolts. There's more in the article, including what a bolt's "yield" is and how it behaves once you've reached or surpassed that yield.
Last edited by Volksaholic; 04-02-2010 at 08:07 PM.