2003 530i Exhaust leak

[javarithms]

I have a major exhaust leak at the downpipe connection after installing new gaskets. My question is which way should the exhaust gasket be installed? Or does it not matter?? The sides are not symmetrical so I'm inclined to think there is a right side.

Does this side of the gasket face the front of the car or the rear? Also, what should I torque the nuts too?? Could not find that info anywhere including TIS. Thanks!!

[effduration]

[QUOTE=javarithms;30483568]I have a major exhaust leak at the downpipe connection after installing new gaskets. My question is which way should the exhaust gasket be installed? Or does it not matter?? The sides are not symmetrical so I'm inclined to think there is a right side.

Does this side of the gasket face the front of the car or the rear? Also, what should I torque the nuts too?? Could not find that info anywhere including TIS. Thanks!!/QUOTE]

I think they're reversible..someone will correct me if that's not correct...but You should be able to undo the nuts and bolts and re-attach...make sure they are good and tight.

[rlordjr]

Make sure the flanges are seated correctly before you tighten fully. According to the German mechanics the nuts should be GuttundTeit

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[edjack]

Download this: https://www.atlascopco.com/content/d...33864801_L.pdf

Page 9 has a torque table for M-threaded fasteners.

[Twistytee]

I’ve changed these twice now and never noticed a leak or issue with orientation. I did soak the fasteners in CLR for 24 hours before re-install. I think they are brass nuts to prevent rust seizure. The soaking removed any corrosion and made the install process smooth.

[edjack]

Good tip! Yes, BMW have used brass nuts for a LONG time.

[djb2]

Gaskets have slotted bolt holes, often on only one side, to handle manufacturing tolerances. Some have one tight hole, one slotted, and the rest loose to hold the gasket in alignment. Oil pan gaskets sometimes have tight corner holes to hold screws for initial installation for people with only two hands.

The bolts/studs are Inconel, a heat-tolerant stainless steel. The nuts are copper-coated steel. Always use new ones. The don't need to be from BMW, but you should get them from an experienced BMW parts vendor. Solid copper nuts aren't strong enough and other plating metals won't stand up to the heat, so don't substitute something from the local hardware store.

Since they are steel nuts, they get the standard torque for the fastener size. From my notes:
Downpipe to exhaust connection, and bracket 14mm (deep), M10 45 Nm

[javarithms]

Thanks for the replies guys. I loosened the (O.E brass) nuts and tighten them again but I still have pinhole leaks when I pushing air through the exhaust and spray soapy water on the flanges. How do I know if the exhaust is seated correctly?? Also, what is the correct method of installing the exhaust? Start from the front and work my way back or does it not matter?? Thanks.

[djb2]

It's much faster and easier with two people, but you can install it with one.

Support the exhaust from the rear a few inches below its final position. Make certain that it can slide forward without dropping off the support. Connect to the downpipe and hang starting from the front, leaving the fasteners finger tight. Once in the final position go back and torque to spec starting at the front. I recall that there is one fastener that you can't reach with a torque wrench, but the hangers aren't critical.

[javarithms]

Ah...crap...maybe that's the problem I connected the rear first and and then connected the downpipe. So if I loosen everything but not disconnect them can I start from the front and work my way back or you recommend loosening the downpipe and disconnecting everything else and start from the front and work my way down?

[Twistytee]

I always start from the front by connecting the midpipe to downpipe with those gaskets. I put a floor jack under the muffler and hang it last. I also loosen or remove the center support bracket and usually re-install it after both the rear muffler section and midpipe are connected.