S52/M52 single vanos piston nut

**JRB1171** · 01-15-2022, 01:03 PM

Unfortunately I rounded off the corners on my vanos piston nut. This is the 18mm custom nut that's notoriously hard to remove due to being extremely low profile. At this point I'm gonna need to trash it to remove it for the anti-rattle fix. I need to source a replacement, so I'm looking for someone who has one or knows where to get one. I've got a 2000M roadster convertible with S52 single vanos

**petro55** · 01-15-2022, 02:58 PM

I also need one. How did you end up removing it?

I emailed a couple places and am still waiting for reply.

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**pbonsalb** · 01-16-2022, 08:55 AM

Use a socket or wrench that is not chamfered so it can grip all of the low profile. Grind the chamfer off if you don’t have one without. Sand lightly to remove any sharp edges that may gouge the vanos.

Alternatively, keep the socket or wrench very square to the nut by pressing down on the ratchet or wrench head. Many don’t hold the handle so the wrench or socket is perfectly square and it pops up and off, rounding corners along the way.

Put the vanos in a vise so you don’t have to also worry about holding it.

**JRB1171** · 01-16-2022, 09:37 AM

I still haven't gotten the nut removed. i've tried everything so far to get the nut off and no luck. I think I had the special socket (no chamfers) at a slight angle which was what rounded it in the first place. After iit was slightly rounded I hit it with impact wrench and that just rounded it more. At this point I'm going to try a more aggressive "bolt out" socket that will dig into the nut. If this works, I will get the thing off but it will be useless when I'm done.
I did try torching on the nut, but I didn't want to cook the bearings that sit right behind the nut inside the piston so I didn't go too aggressive on the heat.
If I can't find a source for a replacement nut I will bail on the anti-rattle repair and just do the seals and be done. I don't have a lot of rattle, but at 87k on the car I figured I'd do seals + rattle so I don't have to take the car apart again next year.

**pbonsalb** · 01-16-2022, 10:31 PM

Just buy another vanos. I don’t think you can buy another nut. Maybe could make one.

**Hallatauer** · 01-20-2022, 02:52 PM

I've rebuilt several of these units... I have never seen that nut available for sale. You do have to be careful getting it off... Besian Systems sells the a socket with the chamfer ground off. I used it and you still have to be careful. Square on with an impact wrench... helps tp have a second pair of hands/eyes while you do it. Just another PITA.

**AJLM34A** · 01-25-2022, 08:55 PM

There was someone that made a replacement nut for this and instead of a hex, there were two round holes 180* apart and a special socket that had two round pegs that fit into the new nut. I searched and could not find it, but I did find a place that sells a steel nut with their rebuild kit;
https://vanos-bmw.com/product/single...-kit-nut-6-cyl

^^^^^^^^^I have never ordered from them, just found them searching.

The best way to take a stripped nut out of the VANOS, get two round punches, find a drill bit that exact size, you want the punches tight in the hole you drill. When you drill into the aluminum nut, go with light pressure, it will go through the aluminum easy then stop when it hits the first component inside the VANOS which is a flat washer. Insert the two punches and hold the opposite end of the punches(the end that you would normally hit with a hammer) with something that would hold both ends tight, a duckbilled vise grip that a bodyman/fabircator would use works great. Holding the VANOS unit in a vise, gear side down, PB or WD40 the outer area of the nut, put a pry bar between the two punches and it should turn the nut out.

When you drill the nut, you might dimple the impossible to find flat washer. Easy fix. Deburr the side that the drill bit hit with a file, make it smooth. When you install the washer, dimpled side toward the nut, the side the drill bit touched towards the needle bearing.