TobyB contact me...or just answer here

[jakeb]

You said you have been using the victor reniz head gaskets with good luck. My head is still leaking with this MLS gasket...

I am going to pull the head again and try the victor reniz that I have.

What are the torque procedures that you have been using?

I only have ft/lbs torque wrench....will that be an issue? I don't have the degree style. But if I need I can find one.

TIA,

Jake

email me through the link above if you want

[winstontj]

Once they are torqued they stretch and can not be re-used. There was an excellent post a while ago about fasteners, stretch, quality of fasteners, etc. Certain fasteners stretch upon applying the correct amount of torque for a number of reasons, mainly to give the user a margin of error. As the head gasket breaks in and adjusts with the heat of the motor the head bolts accomodiate this and keep proper torque. If you attempt to re-use your head bolts you will end up with a leaking head gasket sooner or later every time because the head gasket shrinks as it breaks in, leaivng the bolts loose. This is a very over-simplified, off the cuff explanation so I hope you get the idea. If you ARE using new head bolts, then put a straight edge on the block and head before re-assembly to double check nothing is warped. Unless you are running forced induction or crazy compression ratios you should be more than fine with the stock BMW gasket.

Invest in a $20 Haynes manual at the very minimum if you haven't already. Head torque diagram is listed very clearly. Torque head bolts to 54 ft/lbs or 75 Nm. There are ten (10) bolts in total (5 per side). I reffer to front as the camshaft side, or as if you are standing at the front of the car, looking at the rear. Tighten the middle bolt on the exhaust side first, then middle intake side second, fourth bolt back on the exhaust side third, second bolt back on the intake side fourth, second exhaust side fifth, fourth intake side sixth, first exhaust side - right next to the camshaft - seventh, fifth bolt all the way back on the intake side eighth, fifth bolt all the way back on the exhaust side ninth, finally, the first bolt on the intake side tenth.

HTH & good luck,

TJW

[TobyB]

and realized that I'd been following old instructions!

The old instructions that came with the Reinz gasket gave 2 or 3 torque steps in NM- I seem to remember that you torqued up to 60 NM (40- something ft- lbs), gave it a heat cycle, then add 33 degrees more rotation. The 33 degrees seemed to bring it right around 65 ft- lbs.

The new instructions say to torque it to 40 NM (30 ft-lbs), wait 20 minutes (!!!) add 33 degrees. Then heat cycle it, and add 25 more. Now, of course I read this after installing mine, so I'd already torqued up to 60 NM.... I suspect it'll be just fine.

The one I put on at the track got pretty brutal treatment- we torqued it to 65 ft-lbs, qualified, and then retorqued it (33 degrees, which was darned close to 65 again) HOT! It seems to have held... unlike the rocker!

What I've noticed from all this is that their 'degree' notation seems to correspond very closely to the point where the bolt wants to stop turning. You'll be pulling smoothly, resistance will be pretty constant, and at right about 33- sometimes a little earlier- resistance in the wrench will go straight up. As in, this thing is TIGHT now! And that seems to be where they want you to stop. I'd always read the thing about mechanic's 'feel' being better at getting a joint evenly compressed... now I'm starting to see what they're talking about...

The other thing is that you tend to end up with torque values that are significantly higher than factory, in the 65-75 ft- lbs range. In fact, the head on the racecar was over that- and that was AFTER I'd broken the bolts loose.

Follow the instructions- they really do seem to work better than the old way!

hth,

t

[TobyB]

but I'm going to.

The M10 doesn't use TTY (torque to yield) bolts in the head.

So you can reuse them if you want to.

I have yet to buy new head bolts-

I think I'll spend money for the studs when I do. Just to try 'em.

The M20 does use TTY bolts, however- so those get changed with the gasket.

But they don't cost much money, so it's certainly not going to break the bank if you get new ones, and if it makes you feel better, why not?

I WOULD buy new rod bolts, though- they do a LOT more work in cyclical stress... note that they torque to almost the same value as the head bolts, even though they have less than half the cross- section of the head bolts! Oh, yeah, and they have a fine thread, so they get even MORE static load on 'em...

t

[jakeb]

thanks for the info. Unforntuanally I do not have torque wrench that will give me a degrees. Only the click type torque wrench.

So...torque to 30ft/lbs...wait 15 minutes... torque to ?(55ft/lbs), heat cycle and torque to 65ft/lbs? When torqueing after heating should this be done hot or cold?

Also to the best of my knowledge the m10 head bolts are not true stretch bolts and can be reused. I spoke with jeff @ ireland about this as well as others and they said they can be reused.

[Guest Anonymous]

winstonj the BMW M10 and M30 head bolts are not strech bolts. those were only used on the M20s

Sam

LaValle's Import Restorations

[TobyB]

cut a big circle out of paper, and fold it in half, then into quarters. There's 90 degrees.

From there, it gets harder- half and half again gives you 22.5 degrees,

but you kind of have to guesstimate 33 degrees. I use a degree wheel that's usually used for the crankshaft- but end up eyeballing it a bit, as it doesn't really accurately line up with the wrench as I turn.

Technically- snug the bolts down 'just barely'- then go to 10, then 30. wait 20 minutes, then turn 33 degrees. Give it a heat cycle, and add 25 degrees. It doesn't say if you're supposed to wait for it to cool after the heat cycle- I do, but only because I want it to be cool to do the valves.

You'll be amazed at how much it loosens after the heat cycle.

Yes, as a check of your homemade degree wheel, see if you pull 55 ft- lbs the first time, and 65 for the final torque. But try the degree method- it really does seem to work!

(frankly, as long as you snug them down evenly, starting in the center, and make sure that they're pulled to 55 or 60 after a heat cycle or 2, I suspect you'll seal just fine)

hth.

t

[TobyB]

I just got back from the shop-

here's what the instructions ACTUALLY say-

1 Torque to 37 NM

2 torque to 60 NM

3 wait 15 min (!!!)

4 rotate the fastener 30 degrees

5 warm the car to 80 degrees C for 20 minutes

6 rotate the fastener 25 degrees.

That's not TOO far off what I'd been doing- but it's even MORE rotation than I've used. And after 4 races, a gasket torqued as we'd discussed hadn't leaked anywhere...

So I dunno- that would explain why the head was torqued so tight the first time I pulled it off. And that gasket had lasted 3 years and at least a dozen weekends...

Sorry about that- guess I'm goin' senile...

t