Cracked Exhaust Manifold

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Cmkinney
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Location: Provo, UT

Cracked Exhaust Manifold

Post by Cmkinney »

I knew I had an exhaust leak and the shop just discovered the exhaust manifold has a crack.

My car is a series 1 euro 1980 635csi with m90 and dogleg.

When looking for a mew manifold, will one from a m30b35 fit? Is the m90 manifold the same as the m30?

Any advice on what to look for would be much appreciated.
bpoliakoff
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Re: Cracked Exhaust Manifold

Post by bpoliakoff »

M90 and other E24s have the same manifold. Check realoem for a part number and cross reference it.The later ones are different. The M90 manifolds are the same front and rear. If you can't find one let me know as I may have one. At the same time, a good welding shop that knows how to weld cast iron can do the repair
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
Cmkinney
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Re: Cracked Exhaust Manifold

Post by Cmkinney »

Thanks! And by later ones, do you mean 88-89? Or did they change after series 1?
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Ralph in Socal
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Re: Cracked Exhaust Manifold

Post by Ralph in Socal »

The M30 went through several exhaust manifold iterations thru the years

Early series 1 cars had a two piece manifold that was bolted together and looks like a log. Very restrictive due to design. Only 1 downpipe

Later series 1 cars had two separate manifolds that are distinctly different. Front and rear are not interchangeable. 2 separate downpipes

Series 2 cars to 87 were all 2 separate manifolds like later series 1 cars. Not front to rear interchangeable also. 2 separate downpipes also. These and all manifolds made previously had 3-bolt flanges

88/89 cars are M30B35 and use a different two piece manifold with larger flanges for better flow. These were also designed to scavenge exhaust gases for better performance. The front and rear manifolds are identical. Easy way to ID is the 2-bolt flange

Rumors are that the M90 used larger 2 inch 3-bolt flange exhaust manifolds specific for the M90 but I can not substantiate with facts

Please post pictures and part numbers if you can

Ralph
There is a very fine line between "Hobby" and Mental Illness.

85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)
bpoliakoff
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Re: Cracked Exhaust Manifold

Post by bpoliakoff »

Ralph, correction. M90 used 2 seperate identical manifolds with front and back interchangeable.
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
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