Re: R & R Cylinder Head (archive)

The answer to your first question is up to you. Some insist that the bolts be replaced, others simply re-use clean and the old bolts. I chose the latter and now have driven 70k miles since replacing the head gasket. However, if you are concerned, spend the $3.00 per bolt and buy new ones. When you install cylinder head bolts, the bolts are tightened in three stages:

step 1 : 45 ft-lbs
step 2 (wait fifteen minutes) : 60 ft-lbs
step 3 (engine at operating temperature): turn a further 35 degrees

The tightening sequence is from the middle of the head outwards to the front/rear of the head. Make sure that the bolt holes in the block are free of any oil or dirt otherwise tightening the head bolts may crack the block. Also, the torque values assume that the head bolts are "lightly oiled".

Regards

Alex

The continuing saga....

I'm in the middle of rebuilding the top end on my '91 735 i and would like to know two things. Do you have to replace the cylinder head bolts ??? (I have seen conflicting info on this). Second, on torquing the head down. Do you first torque in two stages first with a torque wrench and then run the engine for 25 minutes and then torque with an angle of rotation guage while hot, warm or cold?

Any one with a Bentley Manual that can check this for me?

TIA

Monti

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