I'm going to get a cast iron manifold , are the ports in different positions so earlier manifolds wont fit? Does anyone know? I want to replace it by going underneath , without removing the intake or injectors, has anyone done it that way, please share your knowledge ?

As far as I remember you can't do it all from underneath unless you are an experienced proctologist. The air cleaner assembly is above the manifold and removing that means removing all the duct work on the firewall etc. The guys at Autologic did mine as well as the PCV valve and the glow plugs at the 200K service.

I would be very interested to see your comaprison between the manifolds. Check to see if the ports match the gasket. The one I saw on the net had the EGR port coming off cylinder one only. Having less exhaust gas in the intake tract is not ideal for emissions, but I am not sure what effect there is on partial throttle tune. Closed or Full throttle will be unaffected.

Cheers

I'm already bypassing the egr. That was the first thing I tried when I first noticed some exhaust smell.
Can't notice any difference in driving with the egr bypassed, except less hesitation when taking off.
I'm not 100% sure it is the manifold , but everyone says they crack, a mech told me he'd never seen one that didn't have at least a few cracks...

It could be the turbo, I noticed one morning what looked like a stream of exhaust coming out from my front right hand wheel arch whilst I was waiting to turn right, but then it disappeared later...

I've changed the air cleaner element, and are going to replace the breather , just got to find an E-torx socket to get it off, never seen one like it before.
If I have to remove the intake , I'll do it, but I've read the injectors can weld themselves in and be hell to remove.
I'll remove the covers, air cleaner etc, and then go underneath, after I find a cast iron manifold...

Hi Yes you can do the whole job from underneath ,I replaced my manifold with a cast unit.I put the vehicle up on blocks about 6" high ,removed the underpan and done the majority from underneath .The only items I removed from the top were some hoses etc and the air cleaner assembly .No way did I want to remove all the injectors etc when there was no issue with them .It wasnt a bad job to do ,just took my time and a bit of patience.Replaced the turbo while I was at it as well.No leaks now.The ports etc on the manifold I removed and the new cast iron unit I fitted was exactly the same.Only done about 20,000 k since it was replaced and all good so far.

Well , you the man! :2thumbs:
I wanted to know if it could be done without removing the injectors, that's a relief.
The turbo, I'm thinking whether to replace it just to be safe, but they're not cheap.

Did you have to remove turbo to get to the manifold?
Did you just use WD40 to loosen up the bolts?

The cast iron manifold you used, was it from a earlier BMW diesel or a new cast iron manifold made in the the same design as the stainless one more or less?

Yes I had to remove the turbo to get the manifold off the bolts that hold it to the manifold are accessible from the base of the air cleaner assembly,there are a few plugs you remove to get to the bolts,from memory they are a 12 point headed bolt.The manifold I used was a brand new unit I imported from the UK.I purchased original gaskets ,new exhaust manifold nuts etc from BMW.I used a high quality penetrating oil and soaked all the manifold nuts with it as the last thing I wanted was a broken stud. A bit of the work was by feel but as I said earlier it wasnt a bad job.I replaced the turbo as it was leaking oil,a tell tale sign is a bit of oil apppears where the tube goes into the intercooler and runs down the underpan.If you have any more questions let me know.

Nice work Skier1.
I looked into this 2 years ago and have always regretted not fitting the cast iron manifold. I am not sure why the injectors need to be removed? as mine were not touched.

Did you notice any difference in the engine noise as mine has an exhaust resonance from the OEM manifold at 2500 especially when cold.
Cheers Dan.

I dont drive the vehicle too much ,its my wifes car so I cant really say whether it made any difference to engine noise.