Can I Reuse My Engine Bolts?

Both of these engine bolts look exactly the same, yet one of them must not be reused. What is a torque to yield bolt? Why do they need to be replaced with new bolts every time? How can you tell if your bolt has "yielded?"

[fasttoyo]

This should have 16m views not just 16k. Thank you for the excellent explanation.

[JoeBob]

This is great! People are a lot more likely to pay attention to instructions once they know the reasons behind them. Otherwise they may just make up a reason in their head that might not be correct.

[wastelandwanderer]

The Chrysler/Jeep dealer in our area is telling me that they normally don't replace the TTY bolts on the caliper brackets when I did the brakes on my wife's Cherokee. To top it all off, they had 2 of each (front and rear are different) from sets of 4, so I deduce that Cherokee's are going around my area with reused TTY bolts in their brake systems! 🙄 I also couldn't find anywhere the proper torque sequence for these bolts, only a single torque value for the front and rear wheels. Naturally the dealer is no help. Thanks for the great info, it must be spread around. Ignorance will doom us all.

[Tubecraft]

This is great. No one I’m talking to at the moment seems to understand the gravity of not checking specs and torque settings

[koenlauwaet]

Very well explained. I really liked the part where the comparison using the micometer was done. Good job !

[stevehammel]

excellent presentation I learned something about checking bolts for stretch with a micrometer Thanks

[KennethWayne]

Thank you. Exceedingly well-explained and easy to understand!

[georgeliquor]

I recently rebuilt a ford 2.4 diesel engine and used all new tty bolts, i followed the manuals instructions on tightening and all seemed ok, later when the engine was started i noticed bubbles in the radiator header tank and a solid top hose (failed head gasket) i removed the rocker cover and cam shafts etc to get to the head bolts, before removing them i tested them all for tightness with a torque wrench, the specified tightening sequence was for the big bolts 20nm 40nm plus 90 degrees plus 90 degrees so i started my test at 50nm and worked up in 10nm increments, i got to 90nm and all were clicking the torque wrench apart from one which just went round and round. On removal of the head i found it leaking in the area of that one bolt, the bolts i used were from a supplier who sold me the full kit gaskets bolts the lot, the numbers on the head of the bolts were 10.9 i found out that the correct numbers should be 11.2 so i spent a little extra for branded bolts made in Germany and so far no problems all running fine. My question is the first batch of bolts i used were of unknown origin probably Chinese and i am wondering how close to the manufacturers specifications are these bolts are made obviously it must be a random luck of the draw type thing so for all out there in a similar situation dont go cheap on these things they might come back and bite you. Just add, the bolt in question measured an eight of an inch longer than the rest after removal

[mr.deathcatgaming]

Great explanation and demonstration. Good job on the video.

[peanutbutterisfu]

Usually when a bolt it torqued with degrees they are torque to yield I can’t say I’ve ever seen one that wasn’t and I do motor work professionally at my repair shop I own, the degrees is when ur actually stretching the bolts u almost always have a low ft lb torque then the last 1-2 steps is degrees.

[Lupasmagnas]

Outstanding Precision provided with clear detail explaining to even the most basic mouth-breathing knuckle draggers why you cannot just assume you can reuse fasteners although I do think it might be still too much to expect the same to understand concept but it was an excellent presentation

[adamturowski]

If you look closer how light is being reflected, you can see which bolt is stretched.

[nickayivor]

Good Evening Justin Miller take care and have a great day 👍
Thanks 👍
From Nick Ayivor from London England UK 🇬🇧

[jorgesierra]

Thank you for this video, it helped me quite a lot

[briangerrits]

There will be small variations in width between any bolts if they are measured carefully enough. What I'd like to know is when exactly a bolt is too thin to be used. What measurement is considered to be out of spec verses acceptable variability ?

[GlennInLaguna]

What about metal bolts in aluminum engine parts. Are metal bolts galvanized so there is no dissimilar metal corrosion? And if you have to remove a part you should always use new bolts?

[Tubecraft]

The other one you need to do a video on is NOTusing a hammer to release the steering joint taper in the steering arm. Everyone thinks it’s ok to keep walloping it until the eye deforms and pops the joint pin out

[raffuy]

Hi Justin, I'm a rookie to this engine building, Am I correct that even though I see in the service manual to rotate 90degree (2X) does not mean my head bolts is torqu to yield? So can I reuse the bolts? And yes in the service manual it does not say I cannot reuse the bolts. The bolt part number is Toyata 90910-02121. Your thoughts?