Re: cylinder studs: torque or length?

[Mick <bmwmick@xxxxxxxxxxx>]

At 02:20 PM 4/1/2006 -0800, jmerlinw wrote:
>I'm new here (apologies, in case I fracture some etiquette). I have a 1999
>R1100RS with 29,000 miles. I'm the original owner.
>b"      I had a slow oil weep around the right side head gasket (dripping 
>on the
>toe of the right boot)
>b"      I tightened the head nuts two times in 6,000 miles but this did 
>not stop
>the oil weep.
>b"      I decided to replace the head gasket and check the cylinder studs for
>tightness.
>b"      Upon removing the heads, The studs all seemed very loose to me b 
>almost
>finger tight. This is the first time the heads have been off. (The dealer
>did the original retorque of the heads at 600 miles).
>b"      I couldnbt find a torque setting for the studs in the BMW nor the 
>Haynes
>manual. Just for the head nuts. If I tighten the studs to say 20Nm b they
>are too short. The Haines manual says they should have 152.5mm of extension
>above the cylinder sleeve, except for the short one which is 132mm. At 20Nm
>the longer studs are just 146mm, not 152.5mm.
>b"      I took them all out and reinserted them to the correct lengths, 
>but again,
>they seem really loose (barely register on a torque wrench)
>b"      So, I have doped them up good with a high-temp thread lock and 
>have put
>then in to correct lengths. But I wonder...
>
>What is your advice?
>b"      Do I go for the correct length no matter if they seem loose (less than
>5Nm)?
>b"      Do I tighten to say, 20Nm even if that makes them short (say 146mm 
>instead
>152mm)
>b"      Or do I helicoil the whole bunch?
>
>Anyone out there encounter this issue? Advice?

John,
   You need to follow the BMW manual on this one.  Torque each
nut to 20 Nm plus 1800, one at a time.
The M10 screw gets done last to 40 Nm.
The valve cover bolts get tightened to 8 Nm, no more.

Mick
Tucson

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