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head bolts

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disco maniac:
i've just fitted a new head to a 300tdi and wondered what torque settings you all use.

Wolfie:

--- Quote from: disco maniac on February 20, 2008, 21:59:56 ---i've just fitted a new head to a 300tdi and wondered what torque settings you all use.

--- End quote ---
You don't!

It's done by tightening through set angles*. All detailed in the Haynes manual.

*A far superior method from what I recall of the materials lectures at uni

extreme90:
off top of my head its goes along the lines of  this
pinch up bolts by hand
then torque up to 33lbft in sequence ( 1 - 18 is it ?  :-. )
then a further 90 degree in sequence
then a further 90 degree in sequence
then depending on what gasket thickness, 20 degree more on selected bolts ( info will be with the head gasket )

Wolfie:

--- Quote from: extreme90 on February 20, 2008, 23:46:01 ---off top of my head its goes along the lines of  this
pinch up bolts by hand
then torque up to 33lbft in sequence ( 1 - 18 is it ?  :-. )
then a further 90 degree in sequence
then a further 90 degree in sequence
then depending on what gasket thickness, 20 degree more on selected bolts ( info will be with the head gasket )



--- End quote ---
Haynes BOL claims 30 lbft then 60o then 60o again, then an extra 20o on the M12x140 bolts, but I haven't compared that to the proper LR BOL as I only have a 200TDi

Range Rover Blues:
Off the top it's 60 degrees twice, then an extra 20 degrees on the inner rows of bolts, 10 of them closest to the cylinder.

I'm not a big fan of angle-torquing.  It actually relies on the bolt stretching which supposedly is more accurate than torquing properly because any oil on the threads can effect the clamping force, but if the angle torque isn't applied smoothly then the results can be just as varied.

Also the bolts are then limited life, you can use them 3 times on a TDi head (3 times on a Transit) but only once on some engines, the bolts cost more than the gasket.

Typically you tend to see them in bi-metallic engines, ie iron blocks/alloy heads because it helps deal with the differential expansion of the 2 metals.

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