can i re-torque stock head bolts

[supraluver4life]

i believe it hasnt began to leak yet because compression is still great. and by completely pulling the head bolts i risk comprimising the head gasket?? because i want to replace the eventually but if it isnt necessary then i wont

[pablo94sc]

If you have have the head off, replace the gaskets and do not re-use the head bolts. They are most likely torque-to-yield and will have stretched the first time installed and torqued to spec. Buy new ones and save yourself the pain of a blown HG when the bolts fail to properly keep the head mated to the block and lift under heavily acceleration (or boost if you have a turbo).

[cre]

They aren't TTY... I do agree with replacing 20+ year old bolts for peace of mind though.

[steves 86 supra]

Originally Posted by cre

They aren't TTY... I do agree with replacing 20+ year old bolts for peace of mind though.

try finding a nut and a piece of steel tube to fit an old head bolt
put the nut in the vice, the tube on the bolt and install finger tight
now take a stretch gauge and measure the length of the bolt, write
this down, torque to a given setting and measure,
keep repeating this process and see if u get even the slightest
difference, ive done this little experiment and found none
i used to use ARP head studs on all modified 7M's but now i see them
as a waste of money on all but the most highly strung engines
about the last 20 7M's ive built have had std head bolts only 2 ive
replaced them & none have had head problems
one of my engines gets cained at 22 psi every day with nothing more
than metal head gasket stock {second hand} bolts & proper head & block preperation

[cre]

Edited for clarity: I wasn't saying that stretch was likely (actually, I pointed out that the TSRM even provides the measurements to make sure they're fine)... I just didn't think pitting was any more likely. I should have simply said as much. I've only ever had 5 apart that far though. Now you've got me curious, how many pitted head bolts have you pulled from 7M's?

[steves 86 supra]

Originally Posted by cre

Edited for clarity: I wasn't saying that stretch was likely (actually, I pointed out that the TSRM even provides the measurements to make sure they're fine)... I just didn't think pitting was any more likely. I should have simply said as much. I've only ever had 5 apart that far though. Now you've got me curious, how many pitted head bolts have you pulled from 7M's?

ive only come across a couple of pitted head bolts on 7m's usually they
come with a badly coroded head & most often i'll throw the lot out &
start with at least a good head or another engine for rebuilding

[cre]

Tanks for clarifying. I figure it would take a lot damage to the HG, block or head for the bolts to pit.

[GiJoE1000]

Im about to give this retorquing of the headbolts a try on my 7MGE and i had a couple of questions for CRE and/or Steves 86 Supra

The order for tightening...... The link Cre gave has an order for removing the bolts and then further along it has a different order for putting them in, im presuming that i use the order for putting them in to tighten them up? The one that starts in the centre of the block and works out?

Also, Steves 86 supra, you mention a drain bung in the block on the turbo motor? I presume my non turbo motor will have the same bung? I presume the risk here is that if you dont drop the coolant there is potential for the coolant to bypass the gasket and get into the engine during the retorquing process? At the moment im just getting a little pressurised gas into the cooling system but no water back into the engine and def no water and oil mixing. Ill have a look and see if i can find the bung.

Think thats about it, all i need now is a torque wrench!

[cre]

Use them both... the removal order for loosening them a quarter to half turn and then the tightening pattern (which is the opposite) to torque it down.

Yes, the coolant drain plug in the block is in the same place.

[GiJoE1000]

I have retorqued the head bolts now but was it worth the trouble??????????????
So far im not sure?!?! Im not sure how much better it is but it definately hasnt made it any worse.
I was able to drive the car today for about an hour with the aircon on (rather than the heater!) and the temp only moved up by 1 notch when i was in traffic and sat at a set of lights for 2 changes.
I wonder if just flushing the system and putting the 50:50 mix of coolant and deionised water wouldve had the same effect without the several hours spent on the tools!

The drain plug to drop the water out of the block was a bitch to get to and was VERY tight! I couldnt see it behind the heatshields.
After it was refillled with coolant/water, i ran it for ages with the car parked so the rad was up high and the heater on flat out. Also removed the thermostat to help but still had bubbles. Not as many as before but still a fairly constant stream. I torqued it up to 75 ft/lb's with a wrench that was recently calibrated, im wondering if i shouldve gone a few more ft/lb's as ive seen a few posts where people say to go to 80ft/lb's.
The process had definately not been done on this motor before though as after cracking each one off a quarter of a turn, my first run with the torque wrench set at 55ft/lb's saw then tightened a fraction tighter than where they were when i started. Then 2 more runs at 65 and 75.
As i say ill give it a few days to settle and a few more attempts to burp the system and ill make some enquiries about getting the HG done properly.