head bolt check

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Nov 15, 2023 | 05:37 AM

clickbang

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Honda-Tech Member

Joined: Jul 2023

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head bolt check

have the head off my jazz fit 2003.
just wondering if i should replace them,or is there a length check for stretch,to reuse them

Nov 15, 2023 | 08:16 PM

JRCivic1

Honda-Tech Member

Joined: Jan 2013

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From: The South - Roll Tide !!!

Re: head bolt check

What does your factory service manual say about this ?

Nov 20, 2023 | 05:38 AM

hondamark35

Honda-Tech Member

Joined: Feb 2005

Posts: 4,235

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From: Mustard Belt

Re: head bolt check

Quote:

Originally Posted by Mondysh

When it comes to head bolts, the general recommendation is to replace them whenever the head is removed. Head bolts are often designed as torque-to-yield (TTY) bolts, which means they are designed to stretch a certain amount when torqued to specification. This stretching provides the necessary clamping force to ensure a proper seal between the cylinder head and the engine block.

TTY head bolts are uncommon on Hondas. Inspection for damage to the threads or "necking" of the shank from being over-tightened is recommended as is a thorough cleaning before reuse. Otherwise they can be reused more than the number of times one could be bothered to rebuild an engine.

to be pedantic... when used for a clamped joint, all bolts stretch and achieve necessary force when installed to spec.

The "selling point" of TTY bolts is the reduction of variables that may cause out of spec clamp loads like friction of threads, presence of lubrication, bad tool calibration, ect.

OP: I'm with JRCivic1, check the factory service manual. It will mention in the notes that a head bolt(s) require replacement if that's the case. Also a torque spec followed by "...rotate another 180°." is another sign original bolts should not be reused.