Exhaust Manifold Gasket Orientation?

[2004LSB]

Hey everyone,

I noticed the genuine BMW gaskets are made of two different materials; one side appears to be stainless steel (the shiny side), and the other side looks like it is heat resistant and designed to form a tight seal when compressed (I'm guessing this is inconel)?

So what's the consensus on the direction when installing headers? I've done some searching on Google and the results seem to be inconclusive; some say the stainless steel side should face the head, while others say it should face the header. Fel Pro Gaskets says the stainless steel side should always mate with the headers to allow them to "slide" under thermal expansion during normal heat cycling when the vehicle is in operation.

Thanks in advance!

[ATB88]

In this case I'm pretty sure it's stainless steel to head. That's how they were when I pulled my headers off and I'm quite certain they hadn't been removed since the factory.

[ATB88]

I have a related question and don't want to annoyingly start a new thread:

The ring gaskets that mate the headers to the sec. 1 -- do these need to be replaced every time they're separated? *Seems* re-usable, but I don't know anything about this gasket material or how it seals so figured safer to ask just in case. I just put a new set of these gaskets in when I switched to Euro headers, mating them to my stock sec 1. Next week I'll be upgrading to a euro sec 1, is it best practice to replace these gaskets again, maybe since they were mating a diff sec 1 before??

[2004LSB]

I have a related question and don't want to annoyingly start a new thread:

The ring gaskets that mate the headers to the sec. 1 -- do these need to be replaced every time they're separated? *Seems* re-usable, but I don't know anything about this gasket material or how it seals so figured safer to ask just in case. I just put a new set of these gaskets in when I switched to Euro headers, mating them to my stock sec 1. Next week I'll be upgrading to a euro sec 1, is it best practice to replace these gaskets again, maybe since they were mating a diff sec 1 before??

The material seems pretty soft and malleable, especially when these things are sealed up and heat cycled; how do they look when you remove them? If they look like they're still in good condition, I would try re-using it first. You'll know if you have a leak right away and if you have to replace it with a new one, it should be very easy and straightforward to swap out.

Thanks for the tip - - yeah that was my initial assumption since the cylinder head will most likely be machined with tighter and more accurate tolerances than the header flanges.

[Casa de Mesa]

In this case I'm pretty sure it's stainless steel to head. That's how they were when I pulled my headers off and I'm quite certain they hadn't been removed since the factory.

+1

Here is a pic I took from my car when I pulled the factory headers this weekend. Shiny side to the cylinder head, waffle textured side to the headers.

[Casa de Mesa]

Speaking of these gaskets... I got Agency Power headers on sale about 2 mo ago. They came with gaskets. Any reason not to use them? No idea what brand AP included with the headers.

I generally spec OE (specifically, BMW or the manufacturer who makes the BMW part) but these came with the headers... AKA "free-ish"

[ATB88]

When I was gonna install Megan headers I was very strongly recommended against using the free gaskets that came with them. I think that this is generally good advice all around. You really, really don't want to have to take the headers back off again to replace the gaskets if they happen to be shit. It's a miserable job.

In the end I ended up installing euro headers with OE gaskets, but because I'm dumb I installed bank 1 and tightened all 9 nuts before bank 2 was put in place.... meaning I had to then remove bank 1 then do it again. I've never sworn longer or harder in my life. I think it's 100% worth the $60 for OE gaskets for peace of mind here.

[Johnvu]

When I was gonna install Megan headers I was very strongly recommended against using the free gaskets that came with them. I think that this is generally good advice all around. You really, really don't want to have to take the headers back off again to replace the gaskets if they happen to be shit. It's a miserable job.

In the end I ended up installing euro headers with OE gaskets, but because I'm dumb I installed bank 1 and tightened all 9 nuts before bank 2 was put in place.... meaning I had to then remove bank 1 then do it again. I've never sworn longer or harder in my life. I think it's 100% worth the $60 for OE gaskets for peace of mind here.

This was definitely a lesson learned for me. I used the Megan gaskets... which lead to an exhaust leak. The entire cabin would fill up with exhaust fumes whenever I would go anywhere past 4500 RPM. I bought OEM gaskets with the longer exhaust studs and the problem went away. There are some parts that aftermarket make a lot of sense, but the gaskets are something you shouldn't cheap out on or you will do it again. In case you are curious, These are the gaskets I tried using aftermarket and had to switch to OEM later:

Exhaust Manifold Gaskets
Header to Section 1
Valve Cover

Just spend the money or you will have to tear it all down again. I should have just listened to what Obioban said in some of the DIYs LOL.

[Tbonem3]

The OE gaskets are thin, which helps if the headers you're putting on have thick flanges. The aftermarket gaskets that come with chinese headers are thick, and may pose a problem for install, nevermind what their quality/construction might do.

[2004LSB]

Thank you everyone for the feedback - - much appreciated. When I had the "fatboys" removed, I vaguely remember seeing the textured pattern imprinted on the header flanges.

[Casa de Mesa]

The OE gaskets are thin, which helps if the headers you're putting on have thick flanges. The aftermarket gaskets that come with chinese headers are thick, and may pose a problem for install, nevermind what their quality/construction might do.

Got it, this makes a ton of sense. Just orders BMW gaskets.

Are AP headers Chinese made? For some reason I thought they were domestic...

[Arith2]

Got it, this makes a ton of sense. Just orders BMW gaskets.

Are AP headers Chinese made? For some reason I thought they were domestic...

They are made in China like 75% of the headers available for our car. Megan headers are Active Autowerks headers but with a different name. There was a thread on M3forum where someone called around and investigated. They look exactly the same and were made in the same factory. I'm really not sure how Megan Racing got away with it.

With these gaskets, there's a good chance they'll leak if you try to reuse them just because that material kind of peels off a bit.

Never use the gaskets that come with headers EVER. I wouldn't use the bolts either.

[Casa de Mesa]

They are made in China like 75% of the headers available for our car. Megan headers are Active Autowerks headers but with a different name. There was a thread on M3forum where someone called around and investigated. They look exactly the same and were made in the same factory. I'm really not sure how Megan Racing got away with it.

With these gaskets, there's a good chance they'll leak if you try to reuse them just because that material kind of peels off a bit.

Never use the gaskets that come with headers EVER. I wouldn't use the bolts either.

F*ck. I'm an arse. I thought I was supporting an American company... Thought the same with AA's, bought into their whole story on the website.

Regarding the bolts, you're referring to the section to section bolts, not the header studs, correct? I have all inconel ones ready to go (pn: 11621318568) for the former.

Reason I ask, I almost bought new studs - the slightly longer BMW studs, even though the AP headers don't need them - but all my studs stayed in place and look ok, save for some minor corrosion at the tips. Should the studs be replaced "while you're there"? I thought that was no, but...