Gents,


1st FASTENER

Whenever you do the coolant hose removal, pay close attention to the orientation of the clip L bent and how only a tiny part of the stainless clip is supposed to lock the hose to the "mating" device.
You are also NOT TO REMOVE THIS CLIP, simply lift up like 8mm, that's it. This clip when removed totally, can loose its pre-tension easy. See the PDF attached.




Observe where is the stopper-groove on the plastic body to accept that L shaped bent of the stainless steel clip. Its not always the same between hoses. Follow the groove.



.See, the stainless steel clip only locks at 2 point, measuring only like 1cm per point, 180 degrees apart. Very small locking area.



My indie workshop , one of the staff installed the stainless steel clip wrong orientation of the L shaped end and it took months for the hose to finally pop-out on its own and coolant gone !!!
Yes, months.... not days or week. I was lucky it pop-out when car at home and engine was OFF. If at highway speed, no coolant low warning will save this engine from warping....guaranteed.
This happened to me back in 2019.


I have assisted a member here by reminding him to inspect the same, I forgot his name.... which his radiator hose pop-out too and he was confused as to why that happened.


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2nd FASTENER.

This one I discovered today.
My nose is very sensitive to smell/odor.
The past 2 weeks or so, I can smell a little of un-burned fuel when my engine started cold.
No it is not from exhaust at tail pipe end, it is at engine bay.
Bank 2 of LEFT Bank to be exact.
When engine is hot, the smell goes away.

I thought my gasket failed, the ring version an M276 3.0 Turbo uses, M276 3.5NA does not use this ring gasket.

Photos below from Ebay :


.


Above is item #525 or #520 of EPC below





Or I worry that the compression cone/flange of the exhaust fitting has minor scratch, see below : ( Item #505 in EPC for M276 3.0 Turbo )





If M276 3.5 NA, the compression cone is direct at exhaust manifold complete assy.





So I use my Teslong boroscope to inspect. DAMN !!!, how come the M8 bolt can be so loose ? So I thought .



.




This is the M8 bolt in discussion. Only possible to inspect using mirror or boroscope








Want to know what actually happened ?
Totally Uncle Murphy.........

This bolt is a 20Nm only for its tightening torque, M8 is size 13, so small bolt. 20Nm is nothing at all, so light a tension.




So, this is double Murphy.
At the 3rd time the exhaust was removed, for the Lambda + Oxygen sensors replacement while also replacing the torn rubber boot and still very good middle drive shaft bearing + its rubber mount....I use NEW EXHAUST BOLTS.
Because the old bolts were too rusty already.




Guess what actually happened ?
It so happened that the BANK 2 ( LEFT SIDE ), L side or outward side welded NUT female thread for the exhaust bolt were no more normal....DUGHHH !!!!




The resistance of the bad female thread is MUCH higher than 20 Nm. I tested it today.



.
I have to slowly "damage" the bolt male thread to suit the semi-damaged female nut thread.
It is OK today, but next time I need to remove the short #505 pipe and weld a new NUT.





I have always fear bolt and nut near turbochargers, they get thread damage from heat often and gasoline engine is hotter than diesels for their turbocharger section.
I run to 970C / 1,778F on the CAT as per the data log when I pushed my engine.


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This is Bank 1, RIGHT side. Both bolts OK.



.





So, this is just a reminder to you guys, use a mirror or boroscope to confirm the proper thread depth/engagement of exhaust bolts where it is so close to chassis and a blind spot.
Don't rely on torque wrench resistance alone .


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The other Murphy part is that, 1st and 2nd time the exhaust was removed, the old bolts did not behave like this.
That meant that the bolts male thread has matching "mild-damage" to the nut "mild-damaged" female thread.... so all was good back then .
I guess it made sense that both the old bolts and its lady NUT got heated up together always, so their threads were kinda mild-damaged at the same time and pattern .....LOL.




END OF REPORT

 

Hoses I purchased came with new retainer clips. As with Brake hardware, I seldom reuse any sundry parts. Spent extra time removing, reinstalling, and inspecting the hose ends to guarantee a perfect final connection.

 

I ended up re-doing all replaced hoses by myself...LOL.