AAZ MLS head gasket torquing procedure

[Jory]

I just finished building a 1.6 N/A hydro motor.
I decided to go with an AAZ metal head gasket instead of fiber.

My question is, what is the torquing procedure for the MLS gasket? My understanding is to do the initial torque +90º and then no further torquing is necessary (no re-torque after first warm up or 1000 miles).
Is this correct?

Thanks,
Jory

[monomer]

What bolts/studs are you using.


Use the procedure they call for, in the order they call for.

[Jory]

Not building for power, so I went with stock bolts.

However, my understanding is that the torquing procedure depends on the gasket type, not the bolts.

[theman53]

I don't have an aaz bentley but if you know whatever the aaz engine HG sequence is that is what I would use.

[Blocksmith]

What bolts/studs are you using.


Use the procedure they call for, in the order they call for.

x2

Realize that I have no practical experience in this area, but from the reading I've done here and elsewhere I'd have to vote for following the procedure for the stock (stretch) bolts that you used. It would seem to me that the torquing procedure would be dependent upon the bolts, rather than the HG (stretch bolts vs. arp studs....)

I don't have an aaz bentley but if you know whatever the aaz engine HG sequence is that is what I would use.

I could also agree with this, however--provided that the stock bolts for the AAZ and 1.6 share the same specs / characteristics. From what I gather you used the 1.6 bolts--in which case I would think the way to determine whether the extra torquing procedures for the 1.6 bone-stock setup is due to the qualities of the HG, or the bolts. Anyone with practical experience or collected knowledge care to comment?

Things that would be helpful:
1) whether or not the AAZ procedure shares the extra torquing procedure
2) whether or not the stock AAZ head bolts stretch

[jb86]

I had a metal head gasket from aaz installed on my 1V engine
1.6td hydraulic head
Oem stretch bolts
The torque procedure is the same as the fibre gasket
Same torque
The only difference is you don't re torque after
jon

[Jory]

Things that would be helpful:
1) whether or not the AAZ procedure shares the extra torquing procedure
2) whether or not the stock AAZ head bolts stretch

1)I don't have an AAZ manual on hand. It would be helpful to know the AAZ procedure.
2)The AAZ uses stretch bolts, this I know.

Like I said earlier, I'm quite positive the torquing procedure is due to gasket type, not the bolts.
In my understanding, fiber gaskets tend to compress more with heating and cooling cycles and therefore require a re-torque. MLS gaskets should compress permanently on the first torquing and should not need to be re-torqued.

I'm fairly certain this is the case, I just wanted to see if anyone else had some definite info on it.

[Jory]

I had a metal head gasket from aaz installed on my 1V engine
1.6td hydraulic head
Oem stretch bolts
The torque procedure is the same as the fibre gasket
Same torque
The only difference is you don't re torque after
jon

that's the info I was looking for 

[vanbcguy]

My Bently has different procedures for fiber versus metal HGs on AAZ's... I don't have it handy at the moment though.  I'll try and find and post the specifics later!

[Jory]

My Bently has different procedures for fiber versus metal HGs on AAZ's... I don't have it handy at the moment though.  I'll try and find and post the specifics later!

That would be great!

[vanbcguy]

Bentley for Volkswagen Jetta, Golf, GTI 1993-1999 has this, retyped in verbatim:

4-cylinder head installation procedures...

Step 7 - tighten the new head bolts in stages using the sequence shown

Stage 1 - 40 Nm (30 ft-lbs)
Stage 2 - 60 Nm (44 ft-lbs)
Stage 3 - Additional 1/4 turn (90°)
Stage 4 - Additional 1/4 turn (90°)

On AAZ Diesel engines, if the old style composition head gasket is used, run the engine until it reaches normal operating temperature.  Then retorque the cylinder head bolts in proper sequence an additional 1/4 turn (90°).  AAZ, AHU and 1Z Diesel engines that use the newer style metal head gasket DO NOT require this step.  Retorquing after the first 1000 miles is NOT needed for either style of head gasket

AAZ diesel with composition head gasket only

Stage 5 - Additional 1/4 turn (90°)

[Jory]

thanks a lot vanbcguy, that clears it up for good. 

[R.O.R-2.0]

holy crap, 44 ft lbs then 3/4 of a turn?!

thats ALOT!!!