Are 3.9 Camshaft Bearing Caps Bolts TTY ?

Carl Smith

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Anyone know if the camshaft bearing cap bolts are torque to yield type ? I snapped one re-torquing them to 53 inch pounds, but have a feeling the wrench I borrowed, cheap Harbor Freight, was way out of calibration. I was lucky that it snapped inside the cap and could be easily threaded back out.

I have a better tool and ordered one of those torque wrench digital adapters to check & adjust calibration. Just a heads up for anyone grabbing a torque wrench and trusting specs.
 
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Well, the service manual doesn't say that they are, and it doesn't say to discard and use new ones. However, the tightening instructions kind of imply that they might be.

The bolts may be -W701242-S309, M6 x 43mm. Measure one that you have to be sure before ordering.
  • Install the bolts. Tighten the bolts in 3 stages in the sequence shown.
    • Stage 1: Hand-tighten.
    • Stage 2: Tighten to 6 Nm (53 lb-in).
    • Stage 3: Tighten an additional 90 degrees.

  • s6x%7Eus%7Een%7Efile=n0006483.gif%7Egen%7Eref.gif

 
No information about TTY or not but I broke one as well. I had to use an EZ-Out to get it back out. Talk about nervous... I hope for your sake its easy to get to.
 
No information about TTY or not but I broke one as well. I had to use an EZ-Out to get it back out. Talk about nervous... I hope for your sake its easy to get to.

I got lucky. Snapped mid way and was able to thread it out by hand.
 
Rotation by degrees is not necessarily an indicator of TTY bolts. Stretching a bolt by a torque value can have an inconsistency of 25-35% noted by many ASTM or engineering sites. It’s all about frictional variation, and oiling of threads doesn’t address all of that.

People who have tested the HF torque wrenches have noted terrible calibration, so putting the two together would not surprise me at all about fracturing a fastener.
 
Rotation by degrees is not necessarily an indicator of TTY bolts. Stretching a bolt by a torque value can have an inconsistency of 25-35% noted by many ASTM or engineering sites. It’s all about frictional variation, and oiling of threads doesn’t address all of that.

People who have tested the HF torque wrenches have noted terrible calibration, so putting the two together would not surprise me at all about fracturing a fastener.
 
I have 'clicker'-type torque wrenches, both inch and foot, that came from a different source but may well be of chinese origin. I use them for interim pulls and finish with my Snap-On dial wrench. Problem solved.

KS
 

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