Mitsubishi MLS head gasket questions

johnboy1065 · Jun 18, 2009

Hey ya'll,

I recently bought a mitsubishi MLS head gasket and some ARP head studs for my 1991 talon TSI

I was wondering if it's absolutley necessary to resurface the block when using this head gasket? I used a scraping tool to get the old composite gasket off of the block and am taking the head to a machine shop to make sure it's not warped.

Can I get by with the block not being resurfaced if I make sure I get the old composite gasket off and used a straight edge and a feeler gauge to make sure it's not warped at all?

thanks,
John

FORMONTOYA · Jun 18, 2009

Of course you can do whatever you want. However, there is a reason it is recommended to deck the block and head while using a MLS head gasket....

johnboy1065 · Jun 18, 2009

I have done it on my other car without a problem and its pushing big HP. But hell, ya never really can tell what will happen.

I'll use copper spray to help make sure it seals...

jaden · Jun 18, 2009

idk about the copper sealant but i decked my head, cleaned off the block and installed my mitsu mls with apr studs and never did anything to the block and it seals just fine. as far as i know the block shoulden't warp nearly as much as the head will so you should be good.

FORMONTOYA · Jun 19, 2009

I'm always curious as to why people ask a question that they have no intention of following the answer unless it matches what they want to do in the first place.

Why ask a question if you're going to do whatever in the first place?

There is very little in life that's "absolutely necessary". Things are just done a certain way because over the years it was found that if someone does things a certain way, the end result will be more consistent, accurate and done less often...go figure.

johnboy1065 · Jun 19, 2009

FORMONTOYA said:
I'm always curious as to why people ask a question that they have no intention of following the answer unless it matches what they want to do in the first place.

Why ask a question if you're going to do whatever in the first place?

There is very little in life that's "absolutely necessary". Things are just done a certain way because over the years it was found that if someone does things a certain way, the end result will be more consistent, accurate and done less often...go figure.

I asked it because it gives me an idea of the success rate of doing it vs not doing it based on people's responses.

then after the success rate is calculated you make an educated decision LOL

. I don't create the thread dead set on doing it the way I originally planned....

Littlebeeper · Jun 19, 2009

besides he helped me because i also have one and was thinking of throwing it out. i didn't want to pull the block. I'll just keep it and if i do a head job and the parts store is out or closed i'll use the MLS

as far as his initial reason of getting a success to failure rate, this seemed like a very valid reason. i have read all through these forums and have read lots on MLS and cometic head gaskets. it seems from these readings that the success rate is the same for both. i have read a few failures with a new MLS, decked block and surfaced head. i have also seen success from just a head resurface and reusing the metal headgasket.

rx7ttlm · Jun 19, 2009

Its just normal stuff to resurface the head and block when you use a MLS head gasket.... not saying it WONT work, but you risk having to do it all over again.. feel me?

Champ Masters · Jun 19, 2009

Well, i just replaced my headgasket a couple weeks ago with a Mitsu MLS. I had just the head resurfaced and cleaned the block up with a razor blade. I thought the block looked perfect, then i used a little copper spray on the gasket, put it back on and torqued the ARP's using the proper sequence. And wouldn't you know it. . . . . . the gasket didn't seal properly :cry:

With my rad cap off my coolant is sputtering and bubbling telling me that air is getting in there.

So from my experience, I'd go with a Mitsu composite (I know I will now that I have to take the head off again :cry:

)

dsm-onster · Jun 19, 2009

6bolt arp headstuds (they are bigger than the 7bolt version) plus a composite headgasket is good for big power. Like 600whp power. And it lasts as long as you don't knock frequently.

destruckeclipse · Jun 19, 2009

dsm-onster said:
6bolt arp headstuds (they are bigger than the 7bolt version) plus a composite headgasket is good for big power. Like 600whp power. And it lasts as long as you don't knock frequently.

Can a composite handle big boost though? I was told it was only good to 25psi or so before it would become possible to blow it. The reason I ask is because unless you have a massive turbo you would not get 600 on any low or moderate boost setting.

dsm-onster · Jun 19, 2009

Boost has nothing to do with what a headgasket/headbolts/pistons/rods/anything in the combustion chamber can tolerate. The head gasket can tolerate a certain peak cylinder pressure. Boost is manifold pressure. Cylinder pressure exceed 900psi in many cases during the power stroke. Seeing 30-40-50psi boost pressure during the intake stroke and adding that amount to the compression stroke pressure isn't going to do anything to a headgasket that can handle 500-600whp, because the cylinder pressure during the power stroke is DRASTICALLY higher. If it takes 40psi to make 580whp with your particular setup, then a composite head gasket with properly installed 6bolt arp headbolts can handle it.

Whoever talks about the limit of engine components in reference to boost isn't someone of who's advise you should listen. 25psi using a 16g is VERY different from 25psi using a t4 56trim. Power kills parts, not boost.

destruckeclipse · Jun 19, 2009

dsm-onster said:
Boost has nothing to do with what a headgasket/headbolts/pistons/rods/anything in the combustion chamber can tolerate. The head gasket can tolerate a certain peak cylinder pressure. Boost is manifold pressure. Cylinder pressure exceed 900psi in many cases during the power stroke. Seeing 30-40-50psi boost pressure during the intake stroke and adding that amount to the compression stroke pressure isn't going to do anything to a headgasket that can handle 500-600whp, because the cylinder pressure during the power stroke is DRASTICALLY higher. If it takes 40psi to make 580whp with your particular setup, then a composite head gasket with properly installed 6bolt arp headbolts can handle it.

Whoever talks about the limit of engine components in reference to boost isn't someone of who's advise you should listen. 25psi using a 16g is VERY different from 25psi using a t4 56trim. Power kills parts, not boost.

Perfect, just the clarification I was looking for. :thumb:

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Mitsubishi MLS head gasket questions

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