can i re-torque stock head bolts

[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.

[cre]

A retorque isn't going to fix any problems... If you've already got problems it is a band-aid at best. If you've got no problems and it works, you'll never know.

Do know that with a retorque there is always the possibility of making a problem worse or of creating a problem where there wasn't one. You can compromise the head gasket by retorquing... generally this is caused by backing off the bolts too far or from the metal jackets in the head gasket having gotten brittle and now cracking opening pathways for erosion.

[GiJoE1000]

Well it seems i may have been a bit premature in announcing that retorquing the headbolts didnt work for me.... Have done 300+k's in the car since often in heavy traffic without any movement from the heater guage or the need to put the heating on.

I did pop in to see Paden at Unique automotive in villawood as i was concerned the HG did need doing but by the time i got there it seemed most of the air was out of the system. He suggested that the way i put the coolant in wouldve created a huge airlock in the heater matrix and that is what i think was causing the airbubbles under the rad cap. Air bubbles seem to have stopped now.

So all is looking good.