Headgasket Questions

[Luckypabst]

There's no engineered torque spec for running MLS with studs. Everything you read on here is just a best guess. In fact, someone posted some general MLS guidelines recently that stated MLS is only suited for stretch bolts. Yes, I know there are plenty of success stories otherwise...
You need a near perfectly flat head and deck.
You need a finer surface finish on both deck and head.
A fiber gasket will seal damn near anything by comparison.
Assuming you get it to seal the first time around, you'll be making a heat-sensitive engine even more prone to overheat related head gasket failure.

20+ psi... sure, MLS is nice insurance. Otherwise it's just internet hype.
My experience is pushing 18 pounds in a Vanagon with no issues since I went back to the fiber gasket for 3 years now.

Chris

[8v-of-fury]

DAMN BOIII. You dominated that question!

Lol, all very good points. Not a race motor by any means.. and not over 18psi.. so fiber it is!

[vanagonturbo]

Realtime input here. I have a MLS HG on my Scirocco. It leaks. Not much, just some seapage. The head was machined and it was coarse, not that shiny machining. The block deck was machined the same way. It seeps on the outside but no untoward pressure issues in the cooling system. It runs cool all the time. I run 32psi. Take that for what its worth. I dont think a fibre HG would hold up, and I do agree in the smoothness of the deck surfaces being critical. I am half tempted to swap out the studs for stretch bolts. Studs ALWAYS leak. ALWAYS.

[745 turbogreasel]

20+ psi... sure, MLS is nice insurance. Otherwise it's just internet hype.

I wonder why Volvo went to  MLS gasket as a service replacement on the D24?  They only run 11-12 PSI.

[R.O.R-2.0]

20+ psi... sure, MLS is nice insurance. Otherwise it's just internet hype.

I wonder why Volvo went to  MLS gasket as a service replacement on the D24?  They only run 11-12 PSI.

lots of VW gasoline powered engines use the MLS gasket as stock.. most of them never even see anything close to boost..

and lots of Chevrolet engines use stainless shims for head gaskets.. again, not boosted..

and VW IDI diesels came stock with fiber gaskets, and that fiber gasket will hold over 20 psi safely, but still.. the metal gasket is about indestructible, and 99% of the time, within $5 of the price of the fiber gasket..

[Luckypabst]

I wonder why Volvo went to  MLS gasket as a service replacement on the D24?  They only run 11-12 PSI.

That would be a question for an engineer involved in that decision. However, I don't believe VW ever specified an MLS for the 1.6 as a service replacement.

Chris

[Luckypabst]

I am half tempted to swap out the studs for stretch bolts. Studs ALWAYS leak. ALWAYS.

I think the stretch bolts are necessary to allow for the different expansion rates between cast iron and aluminum. Studs don't give, which forces the gasket to take the abuse... or something like that.

[vanagonturbo]

Persactly!

 FWIW, the engine that I had in the scirocco before this engine, I used a MLS gasket and some random used head bolts that I found in the bolt bin. Never leaked at 22psi. This was on a mechanical block and the sealant that I used for the extra oil return didnt leak either.

[Luckypabst]

It took me 3 tries to get a MLS to seal - I like to learn the hard way, I guess. The 3rd lasted a good long time until the oil return/coolant seal hack failed. I used natural rubber that eventually turned to a sticky gooey mess in contact with Dexcool. More than anything, I need my van to be reliable so it was back to the fiber HG with no issues since.

Chris

[vanagonturbo]

I put a crate AAZ in my van about 20k miles ago. Factory MLS gasket. 30psi of boost. Not a hint of a leak so far...

The sealant that I used on the mech engine with the MLS gasket and random head bolts lasted for 20k miles until I pulled the motor. No leaks there either.

I am beginning to think the studs are not the best choice for a DD/WW. All out race car? Sure.