Hello All,
I wanted to pass along some information on head bolt reuse as I'm sure there are others, like me, that want to avoid replacing them all if there is no need. Opinions vary on this topic so I figure an account of 1 more experience with these could be helpful to someone.
Last weekend I reinstalled the head on my 1FZFE last weekend reusing the original head bolts. 1 head bolt failed during installation and showed the failure in the threaded section of the bolt after my second attempt at installing it. All of the head bolts had measured in spec and similarly to the new bolt I replaced the failure with. This was the 2nd use of these head bolts.
Details:
All but one of the bolts torqued down with exactly the same feel. One bolt felt good until the second 90 degree turn when, instead of ramping up to "really hard to turn" it became easier to turn. I pulled the bolt to recheck it per the FSM and found that it was in spec near the head and just below spec further away from the head just before the smooth section tapers down. Bolt looked good otherwise and since I don't really know where to measure these anyway I decided to blow the hole out in the head and try again in case it was full of oil or something like that. Second attempt at installing the bolt the resistance turning the bolt increased consistently but didn't ramp up to as much resistance as the other bolts had done after the second 90 degree turn. I again pulled the bolt for replacement with a new one and it now it has visible stretching in the threaded part of the bolt and measures the same on the smooth part, as it did before.
Background:
Engine has 230k miles on it, head had never been off, no HG leak, great compression and head checked out great when serviced, ie. was a PM headjob with no indication of bolt or head issues.
My take-aways:
I'll never try to reuse these types of head bolts a third time.
I'll have 2 or more new head bolts on hand if I'm ever reusing head bolts.
With rare exceptions, in the future I'll buy all new head bolts for head installs.
I wanted to pass along some information on head bolt reuse as I'm sure there are others, like me, that want to avoid replacing them all if there is no need. Opinions vary on this topic so I figure an account of 1 more experience with these could be helpful to someone.
Last weekend I reinstalled the head on my 1FZFE last weekend reusing the original head bolts. 1 head bolt failed during installation and showed the failure in the threaded section of the bolt after my second attempt at installing it. All of the head bolts had measured in spec and similarly to the new bolt I replaced the failure with. This was the 2nd use of these head bolts.
Details:
All but one of the bolts torqued down with exactly the same feel. One bolt felt good until the second 90 degree turn when, instead of ramping up to "really hard to turn" it became easier to turn. I pulled the bolt to recheck it per the FSM and found that it was in spec near the head and just below spec further away from the head just before the smooth section tapers down. Bolt looked good otherwise and since I don't really know where to measure these anyway I decided to blow the hole out in the head and try again in case it was full of oil or something like that. Second attempt at installing the bolt the resistance turning the bolt increased consistently but didn't ramp up to as much resistance as the other bolts had done after the second 90 degree turn. I again pulled the bolt for replacement with a new one and it now it has visible stretching in the threaded part of the bolt and measures the same on the smooth part, as it did before.
Background:
Engine has 230k miles on it, head had never been off, no HG leak, great compression and head checked out great when serviced, ie. was a PM headjob with no indication of bolt or head issues.
My take-aways:
I'll never try to reuse these types of head bolts a third time.
I'll have 2 or more new head bolts on hand if I'm ever reusing head bolts.
With rare exceptions, in the future I'll buy all new head bolts for head installs.
. If I was just doing a head refresh or stock rebuild I would go new Toyota bolts or undercut ARP studs.
