Has anyone replace gaskets on the exhaust manifold?

[cpalmer]

I've realized I've got a good exhaust leak coming from the manifold some where on my 78'. It's slowly gotten worse and worse.

I was hoping to maybe wait until I could get a new header to get rid of my thermal reactors, but times are tight and I have no idea when that will be.

So, I need to change the gaskets on there.....She's sounding like a Tiger tank more and more and on drives more than an hour, it wears on me now and leaves me with a headache .

Has anyone done this? It looks pretty straight forward. Take off heat shield, remove bolts, replace gaskets, etc..

I'm just wondering if it is something simple, or, if it's something that is much more complicated and will take some time.

Do I need a torque wrench?

Any advice or thoughts are appreciated.

Thanks!

[thomas_m535i]

It should indeed be pretty straight forward. However, make sure you soak every nut and bolt liberally in penetrating oil (e.g. WD-40) well in advance. In addition, if you want to use power air tools to loosen things, it's really recommendable to take great care and don't force anything (especially with the heat shield bolts, which have a tendency to break!).

When mounting these kind of parts back in place, I always like to use a bit of copper grease on the studs to make future removal more easy. I also found that some of the replacement bolts and nuts from BMW for the exhaust system, are nowadays made of copper. Might be nice to replace while your doing this job.

[Mike W.]

X2 on penetrating oil, but WD40 isn't very good. Liquid Wrench is best IMHO. Expect several of the studs to come out instead of just the nut coming off. Get new copperlock nuts and use them, they aren't expensive and will save you much time and trouble if you ever pull it again. And make sure you use a 6 point socket on the manifold to downpipe nuts, they like to strip.

Are you sure where it's leaking from? It might be from the reactor to downpipe, or worse from the reactor itself, they can need some welding from time to time. Start it up from cold and feel around with your hand, you have 20 or 30 seconds before it gets too hot.

[cpalmer]

Thanks you guys.

I've already taken the heat shields off before, so they are good to come off.

I'm wondering about the thermal reactors......do they come off by themselves or with the header? Can I take them off and plug any wholes with bolts? SOunds like I can't do that from what I have read, so I figure they are connected to tha header as one.....but I haven't really looked.

I did seafoam a couple months ago, of for a couple seconds, I saw some white smoke come from the exhaust manifold/header part of the problem....but it was gone real quick.

And I'll do the hand sweep like you said Mike.

I'm using MMO as my rust breaker now. It seems to cut right through rust in less than a minute.

Thanks again. I know no matter what, I'll go in with a bit more confidence and get the copper nuts and bolts.

Cheers

[T.Hanson]

Gotta do what you've gotta do. I remember appreciating the engine on a stand for access to the bolts. Some are around, under, just enough to make straight in air tools, Not.

A stud out the rear of the back manifold, for exhaust, cat hook up was boogered. Bright idea to replace it rather than ignore it, or clean up the threads. Lesson : Messing around with studs, nuts, pieces exposed to big heat, rust, crud needs extreme care, patience, maybe a torch. Twisting anything off is a very bad, expensive, time consuming aggravation.

[Mike W.]

Thanks you guys.

I've already taken the heat shields off before, so they are good to come off.

I'm wondering about the thermal reactors......do they come off by themselves or with the header? Can I take them off and plug any wholes with bolts? SOunds like I can't do that from what I have read, so I figure they are connected to tha header as one.....but I haven't really looked.

I did seafoam a couple months ago, of for a couple seconds, I saw some white smoke come from the exhaust manifold/header part of the problem....but it was gone real quick.

And I'll do the hand sweep like you said Mike.

I'm using MMO as my rust breaker now. It seems to cut right through rust in less than a minute.

Thanks again. I know no matter what, I'll go in with a bit more confidence and get the copper nuts and bolts.

Cheers

The reactors are kind of like overgrown tin can exhaust manifolds, they definitely unbolt from the down pipe. As far as repairing them, they weld up ok with either gas welding or stainless tig IIRC. But they don't like silver solder or brazing rod. They're heavy sheet metal, so no putting in a bolt to plug a hole. If you have to pull them, you should probably get new downpipe gaskets, but be careful, some places, like the dealer at least once in my times, have sold only a solid steel "gasket" which didn't like to seal. You need a composition one, which is still available, but you might have to order it.

[Jeff Dennis]

CPalmer where are you located? I have two sets of manifolds to replace my thermal reactors as advised in this forum I only need one set.
Let me know if you are interested in the spare set.
I've not done the replacement yet on my car it runs cold and without issue. I do not know if they bolt up straight to the down pipes maybe one of the others here would know. These are the 3.0 euro manifolds for the M30 as fitted prior to the reactor version.

[Mike W.]

I do not know if they bolt up straight to the down pipes maybe one of the others here would know. These are the 3.0 euro manifolds for the M30 as fitted prior to the reactor version.

They're not a bolt up. The mounting flange is at a slightly different angle, it's rotated some and the reactors are about 3" taller. Same bolt pattern, but not in the same place. You would essentially need to cut the downpipes and weld in an extension after you bolt the flanges to the new manifolds. Not a big deal, just not a bolt up.

[cpalmer]

Thanks you guys, very much. I am up in Seattle from Oregon for a few more days and once I get back home I will be tackling this.

On a side note, I was out and about in Seattle at Green Lake Park and I saw THREE E12s rolling around. All older gents, all automatics. I almost was going to run and stop them as I had my car parked right there, but it was a little busy.

Was nice to see them rolling around though.

[Jeff Dennis]

Thanks for the info Mike!