# E46 Under body rust treatment



## M3simon (Jan 23, 2012)

Evening all.
I'm just after a bit of advice on how to treat surface rust to the under side of my 2001 E46 M3. 
Generally she's in good condition however, there is a bit of surface rust starting to show and in places getting behind the under seal.

What's the best process?


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## RicardoB (Oct 18, 2015)

If it's just surface rust, would suggest something like a general sand down, bilt hammer deox gel to treat the rust and some rustoleum combicolor on top to cover and protect. 



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## Simonrev (Nov 26, 2012)

If it were me I'd be removing the loose underseal and surface rust with a wire wheel and then treating with ...

Hydrate 80
Epoxy Mastic
Dynax UB 

All from Bilt Hamber


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## Ultra (Feb 25, 2006)

As above BH from start to finish


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## Harry_p (Mar 18, 2015)

The bits in the first couple of pics should be pretty simple with a wire wheel on an angle grinder.

The last pic though, I'd be amazed if that didn't turn into a hole with a bit of digging.

Anywhere the inderseal is loose or bubblin needs hitting with the wire wheel to go right back to somewhere where it's still stuck firm or water will keep finding its way in and continue to prize more underseal off.


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## slim_boy_fat (Jun 23, 2006)

"The last pic though, I'd be amazed if that didn't turn into a hole with a bit of digging."

Hope you're wrong, that's right next to the jacking point so will entail welding if it's perforated.  Not an easy job.


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## M3simon (Jan 23, 2012)

I'll have another look tomorrow. Thanks for the info guys.


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## M3simon (Jan 23, 2012)

Anybody used POR15 products?
Any opinions?


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## Subc (May 30, 2008)

Check out Buzzweld great products and tons of advice on prep and prevention.
http://www.buzzweld.co.uk/


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## ttc6 (Oct 31, 2017)

I've had my share of rusty BMs unfortunately, they all seem to go there. Hope it doesn't turn out to be too bad but it doesn't look great.

The Bilt Hamber stuff is great, echo the comments above. They're happy to give advice on the phone.

I've used POR15 but not let it weather. It seems OK but I reckon not as good value as BH and it would have to be really good to work any better than their Epoxy.

Hope you get it sorted OK!


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## camerashy (Feb 9, 2014)

I have used BH Dynax UB it’s easy to apply and does a great job at underbody protection


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## Andyblue (Jun 20, 2017)

Just ordered some of the Dynax UC for next door neighbour to apply behind his newly chromed grill and the chromed bumpers on his MGA he's having restored - would def recommend either this (clear version) or their UB


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