TD5 Head bolt oops

**LOVEMYRANGIE** · 13th June 2010, 11:08 PM

The bolt may also have stretched. Generally, bolts where angles are specified for tensioning are TTY or Torque To Yield and these are designed to stretch.

The most common stretch point is where the thread starts on the shank of the bolt. Visually, you will see increased gap at the this point than at the thread start at the bottom.
It usually aligns with how deep the thread actually is on the block, but upper thread damage in the female is also attributed with over tensioning a TTY bolt which pulls the tops out starting the whole stripped thread thing
If any bolts are like this, chuck them and use new bolts.

As the stretched section of the bolt starts to take up in the block thread, they get tight and can either seize or start to strip or cross thread.

I would carefully try to remove it and replace it with a new bolt.
May need to use an impact socket if you broke a normal one, but dont put sudden effort on the bolt, just lean on it and ease it out.

Cheers

Andrew

**Bigbjorn** · 14th June 2010, 09:16 AM

If doing any serious engine building you should always clean the threads of critical fasteners with a tap or a die before installing. Even new fasteners. Remember these are made by the thousand on automatic machines with tooling that has a finite life and items made at the latter end of tool life may be inaccurate size and poorly finished. Try to only use High Speed Steel tools as opposed to carbon or chrome tungsten steel tools. HSS tools are made to a standard of tolerance whereas the others are not.

**Tank** · 14th June 2010, 10:54 AM

Originally Posted by Brian Hjelm

If doing any serious engine building you should always clean the threads of critical fasteners with a tap or a die before installing. Even new fasteners. Remember these are made by the thousand on automatic machines with tooling that has a finite life and items made at the latter end of tool life may be inaccurate size and poorly finished. Try to only use High Speed Steel tools as opposed to carbon or chrome tungsten steel tools. HSS tools are made to a standard of tolerance whereas the others are not.

Spot on Brian, I think it is folly to try and get true torque values without running a tap down every head bolt hole, once tapped, cleaned and LIGHTLY oiled you should test fit each and every head bolt, you should be able to bottom out a bolt by hand and not to use oil under the bolt head is folly as well, Regards Frank.

**Rudolf** · 15th June 2010, 04:09 AM

I bough a new set of bolts (Victor Rienz) just in case I had to remove the head.
The old bolt took some carefull work to get out.
Pushed a smaller rod into the hole and it whent straight through.
Theres a hole in the bottom of No. 2 bolt.
Cleaned out oil as far as i could, inserted the new bolt by hand.
It went in smoothly without any problems.
There already was oil on the threads in the head so I did not bother oiling the bolts.
The first two steps when smoothly but the 90deg started to show similar symptoms.
In the start of the 180deg the bolt chattered a lot then suddenly made a klapping sound.
After that the bolt turned as the others did before.
The 45deg whent smoothly also as the others did.
Will see how it lasts.
Only if I could get the stupid engine started.

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