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Discussion Starter #1
See yourselves...
Tightening the last injector after seals replacement.
The nut still holds on, but feels like plastic, just tried with 1/4 turn and doesn't make too much force..
I think the threads in the aluminium had better days...

What do you think about? It doesn't leak, however I feel that the injector could blow away at any moment.
I hope the stud isn't broken inside, so a simple helicoil could fix it!
 

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Yes, you are going to have to repair that. The bang suggests a sheared stud. Unfortunately you made the schoolboy error of double torqueing. Only ever tighten until the torque wrench clicks. There is never any value in re-applying the force to be sure. If the stud sheared it is most likely excessive force has been used at some time. A good thread lubricant or simply copper grease (or a zinc based assembly compound) on threads and under the nut on the contact faces is the way to help minimise issues such as galling and locking the nut to the stud. Looking at it, it looks like there was plenty or too much force being used. Was the torque figure accurate? I must admit I often don't use a torque wrench for many of these things. I find it easier to feel the elasticity in the metal and tighten accordingly but I guess that is just me.

Anyway, I'm sure this will be a pain. The stud may need to be drilled and if so, then a helicoil repair is likely. I can only wish you the best of luck.
 

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Discussion Starter #3
I think that stud was already shot, the other 4 did it perfectly.
However this was a big torque wrench, the value was close to It's minimum (25Nm), supossely this is not a good idea as the precision drops in that condition (been told so).
Well, always saw everyone double testing the torque. It should be clicked only once then?
 

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I've had one of them snap on me before, I hope you can get it out without having to take the cam carrier off. They are screwed into the cylinder head and just poke through the cam carrier.
 

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Click once. If you do decide to use lubricant on threads see if the recommended torque specifies that. If not reduce the torque figure to take into account the lubrication. There are tables of settings to show this. The torque (turning force x lever-arm) does a couple of things, it overcomes friction between the parts and also distorts the threads and stretches the bolt/stud. Within the elastic limit (or below the yield point) the arrangement will recover. Too far and the threads strip or the bolt/stud shears.On the old Triumph twins the con-rod bolts were tightened until they stretched to a certain length. Stretch bolts are single use only as they are stretched into the yield zone.
I have a range or torque wrenches from newton centimetres to hundreds of newton metres. And remember to dial back the wrench before storing it.
 

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When a torque wrench is in regular use it does not need to be wound back. However, when storing a torque wrench for an extended period of time, users should always wind it down to the minimum scale setting and never to zero.

A fully loaded torque wrench, left in storage for a long period, can cause a set in the spring, causing it to weaken over time. On the other end of the scale, by completely off-loading the spring, other components within the wrench may move fractionally relative to each other. When you reapply spring compression the orientation of these components can change, therefore affecting accuracy. All in all, it is better to leave a bit of compression in the spring while in storage.

No my words....Snap-On's
 

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I did say "dial back", not off and "before storing". Actually the instructions for my Britool wrench I've had since 1969. It still works and is within tolerances.
 
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