No, not at the head. That would be a piece that's stuck in the head, not the manifold.
"...the exhaust manifold (to tailpipe) studs...", at the outlet of the manifold, and the inlet to the tailpipe, right ahead of the first O2 sensor and catalytic converter.
Ford uses TTY bolts everywhere that torque matters these days (as does BMW and others). It's not a matter of clamping force in this case, it's a matter of bolt stretch.Manifold stud no longer an issue; got that sucka out.
Now that we've wrestled all the new chains and guides and tensioners into place, we're just about to do the final torquing and sew it up. But I have a question about bolts.
The bolts at either end of the jackshaft are spec'ed as torque-to-yield, one-time use, so we've ordered a pair of replacements. I get that, since timing in this stupid thing is completely reliant on their clamping force.
However, the harmonic balancer (crankshaft) bolt is spec'ed one-time use as well, and that doesn't make any sense, since the crank sprocket is the only one of the lot that has a key and thus doesn't rely on the bolt's clamping force to stay in time. So I'm planning not to replace it.
Anyone disagree?
I have a B.S. in engineering but I don't design engines for a living. Therefore, I default to the specs the engineers that do design engines for a living provide us. I have studied mechanics of materials enough to know some things about metal fatigue and what stretching bolts does to their strength. There are very good reasons why TTY bolts are not reused. The bolt in queation is used on a crank pulley that sees high heat, massive forces and high RPM rotations. What happens if this bolt fails when the engine is turning 6k RPM? I think it is worth less than $10 to not find out.As I said, I agree with the generalization, but reserve my right (as an engineer) to question cases in which that rule may not apply. That's why I was wondering about the crank bolt. And axial elongation (stretch) and clamping force are just two expressions of the same thing. But it's an academic argument; when we got to the dealer for the other stuff, it was a five-buck bolt, so we got one.
This did not apply to the broken exhaust stud, which they want $85 for.
As I said, I bought the bolt (I'm not, after all, an idiot), but I do like running a good debate to ground.I have a B.S. in engineering but I don't design engines for a living. Therefore, I default to the specs the engineers that do design engines for a living provide us. I have studied mechanics of materials enough to know some things about metal fatigue and what stretching bolts does to their strength. There are very good reasons why TTY bolts are not reused. The bolt in queation is used on a crank pulley that sees high heat, massive forces and high RPM rotations. What happens if this bolt fails when the engine is turning 6k RPM? I think it is worth less than $10 to not find out.
For me, the main problem is I wouldn't know how compromised the strength of a reused TTY bolt would be. The initial torquing sequence is meant to stretch the bolt to achieve proper tightening. Torquing it a second time using the same procedure at a minimum doubles the stretch and might stretch it even more since the cross sectional area of the stretched part of the bolt is less than it should be. It might not be an issue to reuse this bolt but it is a gamble to do so.As I said, I bought the bolt (I'm not, after all, an idiot), but I do like running a good debate to ground.
You understand what I'm talking about in terms of the material characteristics. But if you stop and think about it for a minute, you'll realize that the vibration damper bolt out at the front of the crank doesn't actually run very hot - all the serious heat is out at the exhaust manifolds (once this thing is back together, I'm going to see what the actual operating temperature is at that point, just out of curiosity). Nor is it subject to "massive" forces. As I indicated previously, it's keyed to the crankshaft, so that takes care of the radial load, which is light anyway - the few devices that the belt is spinning. And there's no axial load to speak of, just the force needed to keep the pulley clamped in place. So that's why I'm saying that it sounds like this bolt is way overspec'ed.
If you have the right tool and have it set up correctly, the camshaft can't turn.Well, that's not to say that all Subaru turbos are NFG - it's just that the 2.5GT is a bad combination. The turbo 2.0 litre has a great rep.
But back to today's problem at hand: Now that all the new timing bits are in, we just have to torque all these sprockets - but I don't have a good grasp of how. It seems obvious that the starting point is both ends of the jackshaft, then the timing cover goes on, and finally the cam sprockets. I do have the Taiwanese knockoff tool kit.
Haynes says that the front sprockets get 33 ft-lb + 90 degrees, and the back sprocket gets 15 ft-lb + 90 degrees. BUT...
How do you do this if you can't somehow lock the shaft itself? If I'm torquing the front bolt, how do I know the shaft isn't spinning and tightening the rear bolt, or vice versa?
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