I try to faithfully keep my Jaguar-cratic oath of "first do no harm", but sometimes my brain doesn't comply. The first time opened the filler tap on the Supercharger coolant system it took a really long 1/2" breaker bar and a lot of oomph to break loose the plug; much much more than the 33 foot pounds specified for tightening it, so when I needed to replace the plug after refilling the system a day ago I did not bother to walk down to the garage to retrieve my torque wrench. "Just give it a healthy tug", I thought, "that will be close enough".

If you've ever felt that sickening feeling when the bolt you are tightening up suddenly starts to turn way too easily, you know how I felt when the breaker bar in my hand tightening the filler plug did the same thing. "No, no, ,no!", was the thought in my mind and the sound that came out of my mouth. The web holding the fill point had broken and the whole thing came loose from the casting. Damn!

Fortunately, that fill point has no other opening besides the hose at the high point of the SC cooling system, so nothing leaked and it is hidden under the engine cover so nothing shows, but It will take two wrenches from now on, a pipe wrench to hold the filler casting and another to remove the plug, if I have to drain or refill the SC coolant, and the sickening feeling of it giving way still haunts both my waking and sleeping hours, so if you ever find yourself in a similar situation don't be the dipstick I was; go get your torque wrench and, 'first do no harm".

 

Oh boy. I do know the feeling you had.

I have done similar dumb moves even thinking at the time " I maybe should not do this".

That includes my 2nd marriage!

 

Sometimes even the torque wrench won't save you from old weakened bolts

 

The threads, in the casting, are the weaker part of the joint, in my experience.

 

Looks very poorly supported; bad design

Thanks for posting this. I'll be extra careful with mine

 

That sickening feeling is exactly why I don't use a click-type torque wrench. The click is too similar to the crack of a broken bolt, deep in a head where extraction is a PIA. I tried one, but have gone back to my bending beam-type wrench for comfort's sake.

 

Gave my beam torque wrench away decades ago, too hard to see on occasion, clicker works better 4 me. Start with low settings, and work your way up, after tightening them snugly, by hand. Using new bolts with at least as high of a rating as the stockers if not higher, if your not using new factory bolts.Repeated heat cycles of the motor can affect the bolts, causing them to break on reassembly when retorquing them. Even if they were not overtightened, i've had them break, when you go to break them loose next time you need to remove them. Spend the cash, buy new bolts, and try to avoid this.