Exhaust Manifold Torque Specs
#1
10-24-2018, 08:01 PM
Exhaust Manifold Torque Specs
What are the correct torque specs for the exhaust manifold? The factory service manual is oddly blank when it comes to listing torque specs on just about every thing and for the exhaust manifold it just says "tighten completely." Anyone know the correct torque, or should I just do them "German?"
#2
10-24-2018, 11:16 PM
Veteran Member
The service manual has some errors in the case of specified torques for the exhaust manifold. The torque table in the manual (attached) specifies 18 NM for both, the manifold to head and manifold to downpipe.
The bolts at manifold to head are M8 Grade 10.9 which is, according to the fastener torque charts, tightened to 34 NM. I decided to tighten my bolts to head at 24 NM (which is the torque for M8 Grade 8.8 bolts). When removing the exhaust manifolds, I found 3 bolts missing (loosened and fell out) so I used red high temperature threadlock on the bolts on re-installation because the new bolts from Jaguar parts suppliers come with pre-applied red threadlock (but sometimes come without it).
For the "manifold to downpipe" torque (the four M8 nuts), the manual shows 18 NM in the attached extracted table but it shows 60-80 NM for the "exhaust manifold to cat converter" in the section for exhaust manifold installation. Both appear to me incorrect, especially the 60-80 NM as, at this torque, the M8 studs would brake. I tightened the four nuts (which are Grade 8.8) at the flange manifold to cat converter to 30 NM (24 NM specified for M8 grade 8.8 plus 6 NM to compensate for the friction of the nuts as they are the locking type).
I also attach the general fastener torques chart.
The bolts at manifold to head are M8 Grade 10.9 which is, according to the fastener torque charts, tightened to 34 NM. I decided to tighten my bolts to head at 24 NM (which is the torque for M8 Grade 8.8 bolts). When removing the exhaust manifolds, I found 3 bolts missing (loosened and fell out) so I used red high temperature threadlock on the bolts on re-installation because the new bolts from Jaguar parts suppliers come with pre-applied red threadlock (but sometimes come without it).
For the "manifold to downpipe" torque (the four M8 nuts), the manual shows 18 NM in the attached extracted table but it shows 60-80 NM for the "exhaust manifold to cat converter" in the section for exhaust manifold installation. Both appear to me incorrect, especially the 60-80 NM as, at this torque, the M8 studs would brake. I tightened the four nuts (which are Grade 8.8) at the flange manifold to cat converter to 30 NM (24 NM specified for M8 grade 8.8 plus 6 NM to compensate for the friction of the nuts as they are the locking type).
I also attach the general fastener torques chart.
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Peter_of_Australia (02-06-2023)
#3
10-24-2018, 11:55 PM
The service manual has some errors in the case of specified torques for the exhaust manifold. The torque table in the manual (attached) specifies 18 NM for both, the manifold to head and manifold to downpipe.
The bolts at manifold to head are M8 Grade 10.9 which is, according to the fastener torque charts, tightened to 34 NM. I decided to tighten my bolts to head at 24 NM (which is the torque for M8 Grade 8.8 bolts). When removing the exhaust manifolds, I found 3 bolts missing (loosened and fell out) so I used red high temperature threadlock on the bolts on re-installation because the new bolts from Jaguar parts suppliers come with pre-applied red threadlock (but sometimes come without it).
For the "manifold to downpipe" torque (the four M8 nuts), the manual shows 18 NM in the attached extracted table but it shows 60-80 NM for the "exhaust manifold to cat converter" in the section for exhaust manifold installation. Both appear to me incorrect, especially the 60-80 NM as, at this torque, the M8 studs would brake. I tightened the four nuts (which are Grade 8.8) at the flange manifold to cat converter to 30 NM (24 NM specified for M8 grade 8.8 plus 6 NM to compensate for the friction of the nuts as they are the locking type).
I also attach the general fastener torques chart.
The bolts at manifold to head are M8 Grade 10.9 which is, according to the fastener torque charts, tightened to 34 NM. I decided to tighten my bolts to head at 24 NM (which is the torque for M8 Grade 8.8 bolts). When removing the exhaust manifolds, I found 3 bolts missing (loosened and fell out) so I used red high temperature threadlock on the bolts on re-installation because the new bolts from Jaguar parts suppliers come with pre-applied red threadlock (but sometimes come without it).
For the "manifold to downpipe" torque (the four M8 nuts), the manual shows 18 NM in the attached extracted table but it shows 60-80 NM for the "exhaust manifold to cat converter" in the section for exhaust manifold installation. Both appear to me incorrect, especially the 60-80 NM as, at this torque, the M8 studs would brake. I tightened the four nuts (which are Grade 8.8) at the flange manifold to cat converter to 30 NM (24 NM specified for M8 grade 8.8 plus 6 NM to compensate for the friction of the nuts as they are the locking type).
I also attach the general fastener torques chart.
#4
02-06-2023, 07:22 AM
Veteran Member
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