Headbolt Final Torque Specs?

[BECKSTER]

Hello R3V, I'd figured I'd post my question here after getting mixed answers on other forums.

I'm in the process of replacing my friends cylinder head on his 328i E36 and I've got the head on and following the procedure of the torque pattern, I torque'd the head to 20lb's and then 45lb's, can I go ahead and set my torque wrench to the final torque and finish the headbolts? Or have I done this all wrong because I'm not using the 90 degree trick.

Basically what I'm asking is, what should the final torque be on 24v headbolts, and can I finish the job without the 90degree angle trick?

[pazi88]

It's 30Nm (22 lb's) + 90 degrees +90 degrees for iron block.
No need to believe forum talk when you can check it from bmw TIS: http://translate.googleusercontent.c...FBrzrw_TL92P4g

And what's wrong in the degree method? It's really easy because you can see the 90 degrees with your eyes. No need for degree gauge.

https://youtu.be/ZjKEzgb6lfo 4:09 ->

[BECKSTER]

It's 30Nm (22 lb's) + 90 degrees +90 degrees for iron block.
No need to believe forum talk when you can check it from bmw TIS: http://translate.googleusercontent.c...FBrzrw_TL92P4g

And what's wrong in the degree method? It's really easy because you can see the 90 degrees with your eyes. No need for degree gauge.

https://youtu.be/ZjKEzgb6lfo 4:09 ->

They are at 45lbs right now so isn't it to late to use this method?

[MR E30 325is]

They are at 45lbs right now so isn't it to late to use this method?

Probably not, but I don't have the time to run the calculations to determine if the first 90 degree rotation equates to 45 ft-lbs of torque.

For this situation I would order new bolts and do it correctly.

Head bolts are not something I would want to take a chance on. The head bolts are stretch-to-yield. The yield limit of metal is where the relationship between stress and strain starts to become non-linear. I.e. over tightening them will cause them to be loaded outside of the desired range that they were designed to be. I.e.e. you could get into some nasty trouble.

[ForcedFirebird]

Back them out one at a time, in proper sequence, and torque them properly. IE pull the center bolt, torque to 29ft/lb (40nm), then do bolt #2 etc, then go back and do the full sequence to 90°, then another 90.

Since you never tightened the bolts to yield, they will be fine.

Don't sweat getting the degrees 100% accurate, you can be off several degrees and it won't matter. I always line up my breaker bar laterally/longitudinally to the engine, then just get close to 90 by lining it back up the opposite. So, if the breaker is parallel to the head, I make it stick out to the side - the only time you really need a degree wheel is when they ask for an odd number (such as 37°), a quarter circle is fairly easy to judge by eye, and even an eight is as well (45°).

[TobyB]

I'm not using the 90 degree trick.

It's not a trick, it's the only way to tighten a stretcher.
There is no other way.
You will be assimilated.
There is only the red pill.
No blue pill is available.


Like John, I don't sweat it too precisely when they're tty.
The NON-tty's are kind of fussy, so I have a degree wheel that
I use for those- they want a pretty small angle, like 30 degrees, and
it's not too hard to get it wrong......

...and yes, even the non--tty M10 uses a degree method these days.

t

[M3PO]

You can get a cheap angle gauge for $10 at just about any parts store. While I agree that it's not a requirement, it helps give peace of mind.