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L28 Head bolt retorque

Posted: Sun Oct 28, 2007 10:09 pm
by rhymus
Here's one for the L28 gurus. I've just replaced the head on the MQ. Was told to torque head down in normal fashion, start and warm up, set valve clearance. Allow engine to cool completely then recheck head bolt torque. When I did this, torque has not changed. All the info I can get from datsun z car sites say not to retorque head when hot. I've been reading the FSM on the MQ and it says to retorque as part of tune up maintenance and specifies retorquing head when at normal temp. What are your thoughts.

Posted: Mon Oct 29, 2007 9:10 pm
by PGS 4WD
Alloy head yes?? Need to retorque when cold, starting from the middle and spiraling out loosen one bolt at a time and then retorque to the factory spec, and no more! I assemble all engines with never sieze under the bolt head and on the thread, if you haven't there is no harm in removing the bolt and relubricating it before refitting and torqueing.

I mark the bolt and the head prior to loosening the bolt and you will usually find the bolt will pass the origional mark upon retension, if it dosen't then its tight, don't be tempted to go further, especially with torque to yeild bolts as the tension will drop as the bolts become elastic.

Joel