Enigma346
Full Access Members
So when replacing my head do I need new head Bolts or can I just reuse the ones that are there already?
2003 Ford Expedition XLT
4.6L
4x4
2003 Ford Expedition XLT
4.6L
4x4
Head Bolts
- Thread starter Enigma346
- Start date
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BlackCoffee
Full Access Members
New. Head bolts are torque to yield. You set torque in two stages and then add 90 degrees. A good ($140) electronic torque wrench is great for this.
joethefordguy
Full Access Members
I am ignorant. what does "torque to yield" mean?
BlackCoffee
Full Access Members
Torque to yield is when you tighten a bolt beyond it's yield point. In essence, you stretch the bolt. This happens when you tighten to a torque value and the add some angle, in most cases another 1/4 turn or 90 degrees. Since the bolt has actually stretched, reuse to a torque value is unreliable. So, any bolts that are torque to yield can only be tightened once, then they must be replaced.
It means the manufacturer wanted to sell us more parts and rip us more in the future.
In the old days, around pre 1983 or so they were not TTY.
We reused them many times on many engines without issue.
Then they concocted some convoluted reasoning and convince some people that a TTY at higher torque was better than a stronger bolt at lower.
They "might" have made them smaller diameter and compacted things a little more by doing this but I still would have passed!
We used to buy ARP head bolts for muscle car engines and they were way beyond factory that we often reused. The ARP were used repeatedly without concern by most.
SO now when you do a head gasket(s) you get to spend 26-50 more for a set of bolts or risk one snapping when you torque them to specs.
In the old days, around pre 1983 or so they were not TTY.
We reused them many times on many engines without issue.
Then they concocted some convoluted reasoning and convince some people that a TTY at higher torque was better than a stronger bolt at lower.
They "might" have made them smaller diameter and compacted things a little more by doing this but I still would have passed!
We used to buy ARP head bolts for muscle car engines and they were way beyond factory that we often reused. The ARP were used repeatedly without concern by most.
SO now when you do a head gasket(s) you get to spend 26-50 more for a set of bolts or risk one snapping when you torque them to specs.
Trainmaster
Old School Member
Buy new head bolts.
