Tightening torques and lubrication (for real this time)...

[jimbof]

Forum SW playing up this morning for me...

Come across this yesterday in the AVF / AWX engine repair manual, in the section on engine removal / installation:

 

 

1.3 Tightening torques

Note:

• Tightening torques apply only for lightly greased, oiled, phosphatized or blackened nuts and screws.
• Other lubricants such as engine and gearbox oil are allowed. However do not use any graphite or molybdenum sulphide.
• Do not use degreased parts.

 

Can't see a similar note anywhere else in the other manuals for the various subsystems.  Does this mean that the engine is the exception - ie other fasteners are expected to be dry / unoiled at the specified torque values?  I now have a couple of Norbar wrenches so am only tightening to the book values, but I don't know if I should apply a grease or not before tightening.  Thinking of stuff like, for example, the T45 lock carrier bolts, alternator bolts, alternator / AC tensioner bolts, etc.

[dieselV6]

Locking compound greases them well enough, even in minute quantity. Alu threads can be easily stripped with fully degreased bolts.

But if you grease too much, you may find that the bolt can undo itself after a while, thermal and mechanical stresses can do that.

 

On balance, I prefer using locking compound, unless parts to be bolted together operate in oil, or need to be removed many times. Plus nickel based anti seize on wheel bolts and exhaust fittings/threads.

[jimbof]

Seems so counter intuitive to be getting lubricating effect from locking compound!  Which sort do you tend to use?  

[dieselV6]

Various,  Loctite among others. Locking compounds are plastics/acrylic based, and plastics flow under pressure. Just don't use too much or parts will be bonded forever. 

Edited 27 June, 2014 by dieselV6