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Discussion Starter · #1 ·
This subject was brought up in another thread. As someone who has reused head bolts, I'm looking for proof that Honda head bolts are TTY or commonly known as "Stretch Bolts."
Yes I know $30 will buy you new ones and new is better. Just looking for the truth, not a recommendation.
 

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Autozone thinks they are. https://www.autozone.com/internal-engine/head-bolt-set/honda/pilot

I would guess that they are since this is an aluminum head. Good read: Torque To Yield Bolts - (TTY) - What Exactly Are They.

Sounds like according to Honda you can reuse the bolts IF: Measure the head bolts to determine if they need replacement. If either diameter is less than 11.3 mm (0.445 in), replace the cylinder head bolt.

Page 16, line item #40-41 https://static.nhtsa.gov/odi/tsbs/2016/SB-10083954-2280.pdf


Personally I wouldn't reuse them, but then I always hate doing the same job twice and the cost is worth me not doing it twice.

Edit: Wrong Page number listed.
 

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Discussion Starter · #3 ·
Autozone thinks they are. https://www.autozone.com/internal-engine/head-bolt-set/honda/pilot

I would guess that they are since this is an aluminum head. Good read: Torque To Yield Bolts - (TTY) - What Exactly Are They.

Sounds like according to Honda you can reuse the bolts IF: Measure the head bolts to determine if they need replacement. If either diameter is less than 11.3 mm (0.445 in), replace the cylinder head bolt.

Page 40 https://static.nhtsa.gov/odi/tsbs/2016/SB-10083954-2280.pdf


Personally I wouldn't reuse them, but then I always hate doing the same job twice and the cost is worth me not doing it twice.
I don't want to reuse TTY bolts.
So the question.
 

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Discussion Starter · #5 ·
I have reused head bolts with no issues. This is why I ask. Am I the only one?
Fess up! Lol
 

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What's the FSM say? If you only torque to a value, they are not. If you torque to a value then add another half turn, they are. You won't get to a higher torque rating since the bolts are yielding at that point.
 

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Discussion Starter · #7 ·
What's the FSM say? If you only torque to a value, they are not. If you torque to a value then add another half turn, they are. You won't get to a higher torque rating since the bolts are yielding at that point.
Did you stay at a Holiday Inn Express last night? 😁👍
 

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Did you stay at a Holiday Inn Express last night? 😁👍
I was a TA for all of Statics, Mechanics, Dynamics and a couple of other engineering courses in college. I may not be very smart but I sure hope I'd remember the basics of a stress-strain curve.

Additionally, if you are bolting things into aluminum it's how you know you've stripped the threads before they totally let loose... tightening... tightening... tightening... oh crap that last 1/2 rotation was the same amount of force... then they let loose.
 
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Discussion Starter · #9 ·
Additionally, if you are bolting things into aluminum it's how you know you've stripped the threads before they totally let loose... tightening... tightening... tightening... oh crap that last 1/2 rotation was the same amount of force... then they let loose.
This is the greatest fear. Must make sure you have the correct torque specs. Not just read off an internet post.
 
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This is the greatest fear. Must make sure you have the correct torque specs. Not just read off an internet post.
But if you find the same torque value in at least two different threads (by two different posters) and on a youtube video than you are good to go!
 

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But if you find the same torque value in at least two different threads (by two different posters) and on a youtube video than you are good to go!

138935


Also a former TA here, FWIW. And 2 points off for spelling. :p
 

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View attachment 138935

Also a former TA here, FWIW. And 2 points off for spelling. :p
I said Engineer, not Literature major... As long as my equations are correct spelling is an afterthought...

Now that you've made me consider my past life, I remember one of the Asian professors (no idea what country) would always say Ass-fart when talking about asphalt in our pavement design class... PAVEMENT DESIGN, can you imagine how many times that word comes up?
 
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Discussion Starter · #13 ·
But if you find the same torque value in at least two different threads (by two different posters) and on a youtube video than you are good to go!
I'm quite sure there are more than 2. Maybe when 2 agree?👌
 

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What's the FSM say? If you only torque to a value, they are not. If you torque to a value then add another half turn, they are. You won't get to a higher torque rating since the bolts are yielding at that point.
This is what I assumed, too.

I've been prepping to do the timing belt and assumed that the crankshaft pulley bolt was TTY (40-something lbs.ft + 60 degrees), but neither of the field service manuals I'm referencing say it needs to be replaced. Replacing it isn't mentioned in any of the videos or forum discussions, either.

I'm planning to re-use it, since everyone else obviously does, but I don't understand the "+60 degrees" spec if the bolt isn't being stretched.

Since I only took one semester of statics, I hope someone will pull me from my pit of ignorance.
 

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This is what I assumed, too.

I've been prepping to do the timing belt and assumed that the crankshaft pulley bolt was TTY (40-something lbs.ft + 60 degrees), but neither of the field service manuals I'm referencing say it needs to be replaced. Replacing it isn't mentioned in any of the videos or forum discussions, either.

I'm planning to re-use it, since everyone else obviously does, but I don't understand the "+60 degrees" spec if the bolt isn't being stretched.

Since I only took one semester of statics, I hope someone will pull me from my pit of ignorance.
Well I've seen this type of reference on pre-load scenarios, but I can't see why that would matter for the crank pulley bolt. And it's not a gospel truth, I have no issue with a crank pulley having a different torque method than a head stud or water pump bolts or other more common bolts.

So when I talk about pre-load scenario, I can provide an example. Old Chevy Small Blocks with hydraulic lifters (not the flat tappet variety) require you to tighten the rocker arm bolt until the rocker arm stops making noise then go 1/2 turn beyond to pre-load the lifter. Of course this nut is doing more than holding down a rocker arm, it is pushing on the valve stem and the pushrod, which in turn pushes on the hydraulic lifter which is filled with oil while the engine is running so it's a very "fluid" situation.

Long story short, I would and intend to reuse my crank pulley bolt.
 

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Yes, the head bolts are tty, not worth reusing in my opinion. You are supposed to measure them and see if a specified section has a reduced diameter from stretching. If yes replace, if no reuse. On my 04 civic and a family members civic, both were exhibiting signs head gasket leakage( champagne bubbles coming up through a funnel in the rad). I replaced each head bolt one at a time in both cars. Been at least 40k miles on either car, no issues. The head bolts had lost the ability maintain their clamp load over time. Tty is basically turning the bolt into a spring, and it looses the spring over time.
 
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