I was changing my oil the other day and noticed one of my header bolts was missing on the left cylinder bank. Things that make you go ummmmmm???
So I searched various forums, including Planet 9, and found different torque specs for the M8 bolts. I found 17, 23 and 24 ft-lbs. I have a friend that works for
Porsche
in the state that I live in so I called him (which I try not to do) to get the straight scoop. Turns out the correct spec is 17 ft-lbs which is 23 NM. I easily found the sequence, but if your doing any header work, please take note of the correct torque spec with the correct units.
Good Luck.
Ed
I can confirm that as well....
Mine is probably more like 170 ft lb now.......with the rust
They've been known to come loose on quite a few 987s. I found two loose on my
987.2
and there's a few folks on ******** who have found bolts missing.
17 ft-lb is the
987.1
spec: on the
987.2
it's 18 ft-lb (with a different bolt layout and tightening pattern). On the
981
, however,
Porsche
increased the spec to 22 ft-lb even though it's the exact same engine as the
987.2
. My assumption is that this is an update due to the loosening issue, so I've been using 22 ft-lb on my
987.2
When I replaced the exhaust manifold gaskets I torqued in sequence to 22 ft-lb. After driving for 150 miles I found that several of them had loosened slightly, and I retorqued them one by one again to 22 ft-lbs. They have not loosened again since. So at least on the
987.2
that's what I'd recommend, but YMMV.
Gubi- Thanks for the info. One more thing to add to the yearly torque check. I have the 9 bolt torque sequence and added it all the other documents I keep.
My replacement bolts just got delivered so I’ll be up and running this time tomorrow.
Thanks again. Ed
The torque spec in the shop manual was accurate for installation of new, clean parts. Any friction on the bolts or the female threads will cause the bolt to be effectively undertorqued at that value. If you can, you should run a thread chaser or a tap into the holes in the cylinder head to clean them of any corrosion. Unfortunately, chemical thread lockers (Loctite) don't work in this application due to the heat. I would not be afraid of going to the higher values mentioned above.
Mission complete. I got rotation out of every DS bank header bolts and about half of the PS bolts. Interestingly, the forward most PS bolt was completely lose and I had to replace (the missing bolt that started all this) the aft most bolt on the DS. Correlations?!?
I doubt it will matter much, but as a reference point: 2009 CS, stock engine, lots of track days, 47K miles.
