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2.5 Exhaust Downpipe joint rusty bolts replaced

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colb
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by colb » Wed May 24, 2023 7:56 pm

The exhaust bolts on the downpipe joints had corroded away what was left of the two lower nuts were just about holding the joint together and of course the rust. The original bolts have blind splined heads that grip inside the upper joint holes and were seized in. Cut what was left of the lower end of the bolt so it was flush with the exhaust flange and gave the air hammer a go but it wouldn't shift the bolt. Ended up using a thin cutting disc in the angle grinder and cut a slot along lower and upper sides of the jointing brackets which took the tension off the splined end. A few rattles with the air hammer had them moving and out they popped. Replaced both with Stainless flanged bolts and flanged nuts put some Loctite on the threads, remains to be seen if it holds up to the heat but both nuts were fully tigtened and the joint tested leak free so the gaskets remained intact. I did fill the visible slot with exhaust paste to finish it off.
Upper bolts still have rusty nuts intact so these were left for another day, will be harder to get at these with an angle grinder may have to invest in a Dremel and give that a go.
Video by someone else doing this job but drilled them out,
https://www.youtube.com/watch?v=b8aKbU7rRf8
I tried drilling but my new drills wouldn't touch the original bolts so resorted to the angle grinder and slot method.
Attachments
Lower Exhaust Clamp Bolts and Nuts
Lower Exhaust Clamp Bolts and Nuts
IMG_20230524_122633523.jpg (73.55 KiB) Viewed 943 times
Replacement Stainless Steel Flange Bolts and Flange Nuts
Replacement Stainless Steel Flange Bolts and Flange Nuts
IMG_20230524_134621822.jpg (124.98 KiB) Viewed 943 times
Slot along both Clamps allowed air hammer to drift splined originals out. Slot sealed with exhaust paste to finish off, no leaks, gaskets survived
Slot along both Clamps allowed air hammer to drift splined originals out. Slot sealed with exhaust paste to finish off, no leaks, gaskets survived
IMG_20230524_134907950.jpg (92.26 KiB) Viewed 943 times
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j3nks79
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by j3nks79 » Thu May 25, 2023 8:40 am

Mine were the same. I done the gaskets last month as I had a slight blow.
I manage to knock the studs out with a hammer.
2009 09 Carbon Black Cinnamon E86

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TOMGREEN413
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by TOMGREEN413 » Thu May 25, 2023 11:33 pm

Congratulations Sir.....mine look similar but can't face dealing with it at the moment..
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Street
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by Street » Fri May 26, 2023 7:15 am

Nice approach colb. I’ve tackled them twice by grinding the bolt head flush like you did then drilling through with progressively bigger drill bits.
The second one I did burnt out about 20 bits. I started to think it would have been cheaper to buy an oxyacetylene torch!!
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colb
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by colb » Fri May 26, 2023 11:00 pm

Don't know what grade of steel those original bolts are but my drills wouldn't make any impression on them, slotting the flanges worked a treat. Will have to do the upper two sometime using the same method of slotting.
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TOMGREEN413
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by TOMGREEN413 » Sun May 28, 2023 12:23 am

Great idea, I'll remember this hack :thumbsup:
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Z4Mariner
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by Z4Mariner » Sun May 28, 2023 10:15 pm

I bookmarked this too - it would have come in handy when I owned my 325xi . . . . I think I only went through 4 drill bits.
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Mike6
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by Mike6 » Tue May 30, 2023 5:06 pm

This has been covered a number of times as its a weak point on the car. Mr Exhaust did a good job on mine and gave me a lifetime quarantee for about £180. Be careful with the gasket and make sure you get it from BMW as its the correct diameter. Some gaskets have a fractionally smaller diameter which might restrict gas flow.

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colb
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by colb » Tue May 30, 2023 5:20 pm

Think I killed the post cat sensor with the vibration from the air hammer got a code for it no signal, just another job to do got to put a replacement expansion tank in first, it's got a crack on the side
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colb
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by colb » Sat Jun 17, 2023 8:54 am

New post started on the stuck exhaust sensor and the difficulty accessing the remaining two exhaust joint rusty bolts to split the joint so the rear cat could be removed to get clear access to the stuck sensor off the car.
viewtopic.php?p=2011655#p2011655
Cut to finger has stopped work at the moment and off on hols next week so its on the back burner for now.
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TOMGREEN413
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by TOMGREEN413 » Sun Jun 18, 2023 10:26 pm

Hope you're finger heals soon, have a great holiday.

Gutted to hear about the sensor........what a nightmare :thumbsdown:
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Robster68
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by Robster68 » Tue Jun 27, 2023 10:45 pm

Did mine a while back broke a few drill bits while doing it,luckily I’ve an inspection pit in my garage😉
Attachments
IMG_1590.jpeg
IMG_1590.jpeg (152.26 KiB) Viewed 644 times
IMG_1589.jpeg
IMG_1589.jpeg (150.75 KiB) Viewed 644 times
IMG_1602.jpeg
IMG_1602.jpeg (149.91 KiB) Viewed 644 times

healeyneil
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by healeyneil » Thu Feb 01, 2024 2:37 pm

Finally doing mine. What a job to get to !. Ordered new gaskets from Euro. Wrong size ( huge) so I went in to my local dealer
£25 each !!

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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by healeyneil » Tue Feb 20, 2024 12:17 pm

I got all 4 bolts out eventually thanks to oxy acetylene. All nice and quiet, but the post cat sensors died. One came out ok (ish), but the other took 3 hours, and much blood and swearing.
I can’t get a thread chaser to start in the hole in the manifold. I have ordered a proper tap to try and clear the threads. Removing the exhaust manifolds looks like an absolute nightmare of a job to take on. Anyone got any words of advice please 🤞

Umfaan
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2.5 Exhaust Downpipe joint rusty bolts replaced

Post by Umfaan » Tue Feb 20, 2024 12:47 pm

Advice =Take it to a Exhaust professional- :roll:

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