Cam bolts
#1
Cam bolts
I added this question to closing after surgery but maybe having its own thread would be a better choice.
I've twice broken the vvt cam sprocket bolt on reassembly after replacing timing chains and tensioner on my 2000 xj8. The one that is hollow to allow the passage of oil.
It's my understanding that all 4 cam sprocket bolts should be torqued to 112 to 125 nm. After the first time I purchased a new torque wrench and had the same result, at the same location after achieving only about 70% of required torque. Any ideas my jaguar family?
I've twice broken the vvt cam sprocket bolt on reassembly after replacing timing chains and tensioner on my 2000 xj8. The one that is hollow to allow the passage of oil.
It's my understanding that all 4 cam sprocket bolts should be torqued to 112 to 125 nm. After the first time I purchased a new torque wrench and had the same result, at the same location after achieving only about 70% of required torque. Any ideas my jaguar family?
#3
I thought it was a lot of torque also. I double checked the manual and you are correct for the 112-125 NM's. Generally when a bolt snaps it is because it is bottomed out and the threads are not receiving the torque but the body is. I snapped a tensioner bolt before realizing the upgraded tensioners needed shorter bolts.
I would check for any debris in the bolt hole or any damage. I would also double check the fit up of the sprockets.
I would check for any debris in the bolt hole or any damage. I would also double check the fit up of the sprockets.
#5
#6
These are not the tensioner bolts that come with the new tensioners, I'm talking about the cam sprocket bolts. They torque the 4 sprockets, that have a tapered lock down, i.e., no key way. The original broke while trying to achieve recommended torque, and subsequently a new one also broke.
The threads are fine and the bolt doesn't bottom out, making the broken half remaining in the end of the cam easily turned out.
The threads are fine and the bolt doesn't bottom out, making the broken half remaining in the end of the cam easily turned out.
#7
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#8
These are not the tensioner bolts that come with the new tensioners, I'm talking about the cam sprocket bolts. They torque the 4 sprockets, that have a tapered lock down, i.e., no key way. The original broke while trying to achieve recommended torque, and subsequently a new one also broke.
The threads are fine and the bolt doesn't bottom out, making the broken half remaining in the end of the cam easily turned out.
The threads are fine and the bolt doesn't bottom out, making the broken half remaining in the end of the cam easily turned out.
Logic will dictate that if they dont bottom out and even new one snap, something is wrong with the torque load, henceforth my question regarding size
Last edited by luc; 12-17-2016 at 12:14 PM.
#10
OK, that is a 12mm bolt and torque is correct for that size ( see chart below)
so, the only "difference is that the bolt is hollow and torque "should" be less than for a solid bolt.
For example a 12mm hollow bolt on motorcyle for oil line is about 30 lb-ft
It will stand to reason that if the hole is about 30% of the diameter of the bolt, it should be treated like an 8mm bolt
if that was my car, I would torque it to 40/45 lb-ft and use some blue locktite for added safety
No way than an hollow bolt can be torqued as much than a plain one
Metric Bolts
Maximum Torque, in foot-pounds, for clean, dry threads
Check your Shop Manual !
Bolt size Low Grade Grade 8.8 Grade 10.9 Grade 12.9
6mm 3-5 7 10 12
8mm 8-12 17 24 29
10mm 15-22 33 47 57
12mm 39 59 83 100
14mm 60 101 131 158
16mm 60-94 146 202 247
18mm 60-130 201 283 340
20mm 166-188 285 401 482
so, the only "difference is that the bolt is hollow and torque "should" be less than for a solid bolt.
For example a 12mm hollow bolt on motorcyle for oil line is about 30 lb-ft
It will stand to reason that if the hole is about 30% of the diameter of the bolt, it should be treated like an 8mm bolt
if that was my car, I would torque it to 40/45 lb-ft and use some blue locktite for added safety
No way than an hollow bolt can be torqued as much than a plain one
Metric Bolts
Maximum Torque, in foot-pounds, for clean, dry threads
Check your Shop Manual !
Bolt size Low Grade Grade 8.8 Grade 10.9 Grade 12.9
6mm 3-5 7 10 12
8mm 8-12 17 24 29
10mm 15-22 33 47 57
12mm 39 59 83 100
14mm 60 101 131 158
16mm 60-94 146 202 247
18mm 60-130 201 283 340
20mm 166-188 285 401 482
Last edited by luc; 12-17-2016 at 12:51 PM.
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RJ237 (12-17-2016)
#11
Cam bolts
That is a completely logical view and gives me great confidence going forward. But my only concern would be if their parameters were incorrectly stated in the Jaguar work shop manual, what else may be incorrect.
It always comes back to logic.Thanks for taking the time and getting me down out of the tree.
It always comes back to logic.Thanks for taking the time and getting me down out of the tree.
#12
#13
#14
So close to running
The obd reads MAF VAF Faults. Could this result in a no start situation?
#15