Exhaust joint failed - bolt question

T

T2FFN

Senior member
 East Yorkshire
I've suspected a slight leak in the exhaust for a little while as every now and again I'd hear a hissing, kind of like a bottle of fizzy drink being opened, but it was faint and intermittent at best. While driving today the car turned into a Max Power Corsa with a fart-can exhaust on it. Very loud to say the least. I nursed it in low revs to the nearest exhaust centre (mainly embarrassed to let the revs climb and make more noise :oops: ) and once up on the ramp it was a 5 second diagnosis. 3 of the 4 bolts holding the very back portion of the exhaust, basically the furthest forward connection before the pipes go up behind heat shields etc. were missing. When I say missing, the remaining sections of bolts were corroded beyond looking like bolts with no semblance of thread or structure left, so whether the bolts have corroded off or fallen off is just as likely.

So, the exhaust place couldn't do anything there and then, but recommended an internet check for the forward joint, and how the bolts are incorporated into the join. A quick look at what was there it wasn't clear if the bolts were sunken into the joint section, captive etc.

So, anyone that's removed the exhaust for an E85 3.0, any ideas on the bolt type? Can they simply be knocked out and new ones pushed through? Access looks tight for getting to the bolt head, hence the thought they may be captive heads.

Thanks
 
Checking RealOEM it appears to be simply hex M10x40 bolts x 4. Should be easy enough then to knock out the old and place with new.
 
I had same thing happen earlier in year.
Kwikfit fixed mine for £60. Don't know if they drilled or pressed them out though.
Seems to be a common problem. http://www.z4-forum.com/forum/viewtopic.php?f=3&t=82555
 
Thanks, I've left the same comment on that thread, but:

From RealOEM they don't look to be captive as they're just listed as M10x40mm bolts... so in theory should just push out?
 
Think that's the plan. I'm reading online various stories of them being a nightmare to drill out as they're 'Inconel' and pretty hard. Wonder if Bush will give a fixed price for the work, even if they spend hours drilling them? haha
 
Machine monkey said:
Just get them drilled out and replaced with 4 m8 or m10 stainless steel bolts.
Click to expand...
Don't use stainless bolts, they will fret/seize like crazy, even with ceramic grease applied.

From what I remember the stock bolts are more stud like, with no hex head but a flat head and spline fitted in the manifolds.

My advice is to get 1 size smaller bolts (maybe an inbus) and a copper nut and use them in the (oversize) holes.
If you have a seperate bolt and nut you can always use an angle grinder if things will get really stuck and no drilling or heat is necessary.
Using m10 bolts may be difficult on the back of the manifold flange to use (not much room) with a spanner or socket (with m8 you have more room)
 
If you are talking about the join at the front end under the engine, mine are looking pretty knackered so will require attention. I read elsewhere on the forum that these must be drilled out due to manifolds cracking when idiots take a big hammer and try to knock them out.
 
To close this thread: I went to a BMW independent who burnt out the old studs/bolts and replaced with stainless. Cost £165 all in.
 
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