Rusted Exhaust - Help with nuts

[mike87]

Hi, got an '87 325is with a pretty rusted exhaust. I finally managed to get the area after the cats disconnected, was wondering what nut size the section that connects the downpipes to the headers is - there's 6 nuts. Also, is there a special technique? Do I need a 13mm socket + u-joint + extension + ratchet? I tried just a 13mm socket and it couldn't fit over the nut, but a 14mm socket seemed too large. I'm unsure because the nuts are so rusted.

I didn't want to force it. Any help would be appreciated! Currently letting the nuts soak in WD40 overnight and picking up some PB Blaster later this week.

[FredK]

I am uncertain what the size is on those locknuts.

However, skip PB Blaster or any other penetrant if the car has been driven in the winter. Penetrants don't work well and you'll end up snapping the studs. Then you'll be in a WORLD of hurt.

Get a propane or MAPP gas (preferred) torch, heat them until glowing, then remove them with a socket with a u-joint.

[mike87]

I am uncertain what the size is on those locknuts.

However, skip PB Blaster or any other penetrant if the car has been driven in the winter. Penetrants don't work well and you'll end up snapping the studs. Then you'll be in a WORLD of hurt.

Get a propane or MAPP gas (preferred) torch, heat them until glowing, then remove them with a socket with a u-joint.

hm, i do have a propane torch handy, i will keep this in mind. thanks.

can anybody confirm they're 13mm before I try again? they're def not english-sized measurements right?

[Charley]

I removed mine last week. 15mm nuts on mine (copper nuts)
they were hard to brake loose. brakebar+long extension+ujoint worked
quite well for me.

Charley

[mike87]

I removed mine last week. 15mm nuts on mine (copper nuts)
they were hard to brake loose. brakebar+long extension+ujoint worked
quite well for me.

Charley

15mm? mine are def. not 15mm... hmm conundrum

they go on the two triangular sections on the lower left of this pic:


it's part # 18301737774, #2 on this picture:

[Kershaw]

those are 15mm on most cars. however i have seen one car with a smattering of 15 and 13mm nuts mixed together.