Exhaust flange rusted

M

Marco

Member
 Hampshire
Hi,

The flange where the exhaust connects to the down-pipe is completely rusted and the bolts look like they are about to disintegrate! :o

Took it to a garage, he unfortunately can't get exhaust parts for the Z4 but he advised that replacing the exhaust would be an expensive job, it looks like it comes all in one piece so you can' just change part of it.

The other option I was given is to cut the flange off and just weld the exhaust directly together. I've read another post whereby someone has mentioned that if you do this then you are in trouble if you need to change the clutch.

-Can anyone offer advise on how to solve this?
-Any recommendations on who I can go to to fix this? I am in the Fleet, Hampshire area.

Any help would be greatly appreciated!

Thanks,
Marco
 
Hi Marco,

They all do that.......

The exhaust system and downpipes are stainless steel, but the studs and nuts are not, any half way decent indy with a lift will be able to either burn or cut and drill the old studs out and replace them.

Stu.
 
Why are you trying to separate this joint first of all?

They all look rusty they all go the same way. Unless you are changing your clutch or have another problem just leave it alone.

There is usually no need to ever change exhaust parts on the z4. The system is stainless steel and will probably last longer than the rest of the car. It will be just surface coronation and the bolts will have almost nothing left of them. That is fairly normal. Unless its blowing i would say leave it alone.

The other option would be drill the bolts out. I have done 3 cars now. I wouldn't like to do a a 4th its a horrible job. The inconel bolts are really hard and normal drill bits dont seem to touch them. And then re bolt with new bolts after sealing the joint. Or if you are really unlucky and the mounting bracket is rusted away weld new ones on. I really wouldn't want to weld the exhaust fully from tip to headers.
 
Thanks for the advice chaps...

Machine Monkey, given that the bolts are really hard to get out, it stands to reason they are not going to just fall out anytime soon....I hope. :?

Perhaps I'll try and find someone to give me a quote to just drill the bolts out and replace them, but I feel less concerned now about the whole issue.

Marco
 
I wouldn't stress about it. I haven't seen it but they are probably like 99% of the rest.

Budget to get it done in the future. Probably £150 to cut and drill them out it s a bugger of a job.
 
As others have said it is a fairly common problem which if left can prove expensive - thousands!!
I asked my MOT inspector a few months ago what he would recommend as it seems this problem can also affect series 3 BMWs and in extreme cases has meant they have gone to the scrap yard as repair has been more expensive than value of car. He recommended Mr Exhaust at Reigate so I booked the car in and they were ready and waiting when I arrived. Within 90 minutes they had cut out what was left of the bolts cleaned everything up put in new bolts and sprayed everything up with some sort of high temperature paint and gave me a 2 year written warranty. An excellent job and I would highly recommend them. They charged around £160 but I did buy the gaskets from BMW as I read reports that some gaskets which seem to fit have a small diameter hole which can restrict exhaust flow. If you want their number its 01737243900
 
Seems a common problem.


http://www.z4-forum.com/forum/viewtopic.php?f=3&t=82989
 
Mike6 said:
As others have said it is a fairly common problem which if left can prove expensive - thousands!!
I asked my MOT inspector a few months ago what he would recommend as it seems this problem can also affect series 3 BMWs and in extreme cases has meant they have gone to the scrap yard as repair has been more expensive than value of car. He recommended Mr Exhaust at Reigate so I booked the car in and they were ready and waiting when I arrived. Within 90 minutes they had cut out what was left of the bolts cleaned everything up put in new bolts and sprayed everything up with some sort of high temperature paint and gave me a 2 year written warranty. An excellent job and I would highly recommend them. They charged around £160 but I did buy the gaskets from BMW as I read reports that some gaskets which seem to fit have a small diameter hole which can restrict exhaust flow. If you want their number its 01737243900
Click to expand...

Thanks for posting this number. My bolts are rusty and couldn't get them off today for an exhaust mod job. Booked in with Mrexhaust to remove old bolts and put new oem back in. :thumbsup:
 
DMC63 said:
Mike6 said:
As others have said it is a fairly common problem which if left can prove expensive - thousands!!
I asked my MOT inspector a few months ago what he would recommend as it seems this problem can also affect series 3 BMWs and in extreme cases has meant they have gone to the scrap yard as repair has been more expensive than value of car. He recommended Mr Exhaust at Reigate so I booked the car in and they were ready and waiting when I arrived. Within 90 minutes they had cut out what was left of the bolts cleaned everything up put in new bolts and sprayed everything up with some sort of high temperature paint and gave me a 2 year written warranty. An excellent job and I would highly recommend them. They charged around £160 but I did buy the gaskets from BMW as I read reports that some gaskets which seem to fit have a small diameter hole which can restrict exhaust flow. If you want their number its 01737243900
Click to expand...

Thanks for posting this number. My bolts are rusty and couldn't get them off today for an exhaust mod job. Booked in with Mrexhaust to remove old bolts and put new oem back in. :thumbsup:
Click to expand...


I wouldn't use OEM nuts/studs/bolts as they aren't stainless, and this is what causes the problem in the first place. If you replace with same sized stainless, there is no need to paint anything, as it won't corrode.

Mike
 
I wouldn't use OEM nuts/studs/bolts as they aren't stainless, and this is what causes the problem in the first place. If you replace with same sized stainless, there is no need to paint anything, as it won't corrode.

Mike[/quote]

Mmm, that would appear to make sense. Why didn't they use stainless nuts and bolts to start with? Did they use plain steel for a reason? Surely BMW have been making cars, and bikes long enough to be on top of this part.

Been over on Pistonheads and bimmer and most are saying to stay away from SS.

Apparently stainless doesn't have the same tensile strength under high heat and is known to stretch over a period of time, this stretching allows the seal between the flanges to come apart and start to blow, albeit very slightly. Further compound this with the stainless bolts galling onto the bolt making it impossible to tighten or remove them without cutting.

Obvious use of a high nickel non copper/graphite antiseize may help to avoid galling, but most say it doesn't work. Recommended is mild steel and brass nuts. Tbh, I'm gonna go with the mild steel oem, and the brass oem nuts. Give them a coat of high temp paint at the end of the summers.
 
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