Rear 'Bumper Reinforcement' project - PeachParts Mercedes-Benz Forum

JHZR2 · #1 02-02-2004, 10:02 PM

Hi,

I had hoped to be able to wait until the summer, but today was the day. The left bumper reinforcement, the part that holds the rear bumper trim that comes around the side of the car finally fell off completely. The frontmost bolt had long rusted away, and the rear was getting loose. Today I saw that the bottom part of the rubber trim was loose, adn when I pulled it, it all came off.
Underneath was the broken remains of the left rear bumper reinforcement. Using my sockets, a pair of pliers and a careful application of pblaster, it all came off.

I knew I was going to use POR 15 on it, so Ialready had a silver colored (the color doesnt matter, what I was going to paint is under the trim anyway) set at the ready. Fortunately today it got up to nearly 40F here, so I could do it.

I have taken a few pics, and will post more as they come.

Here is a pic of the left rear quarter panel, with the trim and reinforcement gone. I had chipped away the paint bubbles with a wire brush and screwdriver, then prepped it with the etching 'primer' that came with the POR-15.

JHZR2 · #2 02-02-2004, 10:04 PM

And closer up (Didnt use the macro so its a bit blurry)

JHZR2 · #3 02-02-2004, 10:05 PM

Then put the first coat of POR-15 on the bad spots

JHZR2 · #4 02-02-2004, 10:06 PM

Then did over everything that looked like it had rust or the potential to get rusty.

#5 02-02-2004, 10:07 PM

That's some ugly looking rust, but POR15 is great stuff. I didn't know they made it in silver... i've only seen the black stuff (used by a Chevy-Guru friend of mine).

JHZR2 · #6 02-02-2004, 10:09 PM

The POR 15 had to dry to a point where it was "dry with a sligtht finger drag" before I could topcoat it. They claimed it would usually be 4-5 hours, but instead it took more like 8-9.
In the meantime I taped around the area that I would be spraying with undercoating. I chose undercoating because I know it sticks to paint pretty well, and with a thinner undercoating (I used Duplicolor undercoating because it isnt as thick and goopy, some of the ones you buy in pep boys and similar places are a real mess, because they expand slightly and glob all over the place, causing voids, bubbles, etc) which was duplicolor brand from Kmart.
I dont have a pic of the taped painted or unpainted area, but it didnt look that spectacular anyway.

JHZR2 · #7 02-02-2004, 10:18 PM

I painted it tonight, around 930. I wasnt worried that the temperature dropped below 32, because the duplicolor undercoating has some pretty volatile solvents that will dry easily even at these temperatures. The bottle says that it dries in 10 minutes, so I figure at these temperatures, 30-60 minutes would probably make it nearly all the way dry. I let it sit for about 20 minutes then pulled away the edging tape (I only had duct tape, and used that, thus the mess on the car's surface).

So then the result as shown here (I took it in the dark with flash and flashlight, plus lightened the photo) but it doesnt look that good because of the lighting

JHZR2 · #8 02-02-2004, 10:24 PM

It looks in the pic like the upper edge is crooked at the far end; it isnt. I taped straight along the little edge in the sheetmetal, as the rubber trim comes right up to it. Its all black, so if there is a fraction of an inch gap there, itll look black inside.

I think this will protect that seam from letting water in at the very bottom near the underside of the car, when the rear wheels spray up. Itll also protect the surface, as the POR15 stops the rust and the undercoating wont let water get at the surface anyway.

I think the POR15 was just perfect for spraying the undercoating on. It was the right level of dryness (POR optimally reccomends topcoating within 12 hours if not using a POR branded topcoat), and the undercoating sprayed on quite smoothly. I was lucky enough to get it sprayed on before our next 'wintry mix' storm comes along tomorrow morning.

As soon as the new reinforcement comes in and the sun is shining, I will post some more pics with the finished product.

Id highly reccomend people check under these reinforcements. It appears that the seam around which the rust spots were is a common place for rust to start, and there are lots of exposed edges (for the reinforcement bolts, etc) where rust can start. Getting a coat of undercoating on therer seems like cheap and easy insurance. Plus, if yours are anywhere near as rusty as mine, theyll start getting loose before too long anyhow.

dstelkic · #9 05-10-2008, 02:40 PM

So, how did your project look in the end, we never got to see it finished? I am going through a similar fix up on my 300D but i'm having trouble sourcing the new reinforcements. Where did you get yours?

JHZR2 · #10 05-10-2008, 03:22 PM

That was more or less it. The car was destroyed bya marginally insured driver that caused a 4-car pileup. The car saved my life, and obviously the rust was not enough to cause any structural issues - the car did what it was designed to... much to my sadness.

I got the reinforcements at performance products. They are still available.

That said, any old scrap car oguth to have some. Paint them with POR 15 and they ought to be fine.

Best,

JMH

dstelkic · #11 05-10-2008, 07:57 PM

Well, that's too bad that the car was destroyed, but most important is that you were ok. I assume you still have your 85 300D to enjoy.

I've looked for those bumper reinforcements on old cars, but all the off them were so badly rusted that they usually fall apart as soon as you try to take them off the vehicle. So, I ordered a couple of new ones from Performance Parts. For $40 bucks it is not worth spending too much time driving around looking to find old ones in junk yards.

That POR 15 stuff, where can you get it? I have a patch of rust under one of the reinforcements that I would like to treat. It is a bad and good spot to have the rust, as you can see it unless you know where to look, but it is also out of sight, so you don't have to repaint the whole panel.

Magoo · #12 05-10-2008, 09:51 PM

Don't know if its available in Canada, but check at your local auto parts store or auto paint supplier.

JHZR2 · #13 05-10-2008, 10:10 PM

Thanks, yes, I still ahve the 85, but it will soon be for sale, and Ill be buying an as-new 240D, as a "fun" car.

Anyway, POR 15 can be found at:
www.por15.com

Also check Eastwood:
http://www.eastwoodco.com/

Which has anything and everything for classic car restoration. I like their rust encapsulator paint, their pre-prep stuff, and their waxy coating anti-rust sprays.

Best,

JMH

dstelkic · #14 05-11-2008, 02:07 AM

It looks like Performance Parts guys are shipping to Canada... the web site lets me pick Canada and they are supposed to let me know about shipping costs before the order is complete.

As for the rust products... I've pulled off whatever was left of the bumper support (which was mostly just dust and flakes of rust) and on one of the fenders there is a rust spot about 2" in diameter where the bolt penetrates the body to screw into the bumper reinforcement.... (what a lousy setup that whole bumper rubber is anyway... don't you just wish they left things the way they were in Europe... I know it is because of the bumper 5mph crash test but still) Anyhow, the rust seems to be on the surface and the metal underneath is in pretty good shape. So, I'm thinking I'll send it down tomorrow and prime it. Would any of you recommend applying some of the anti rust products?

I've also noticed that wherever there is a penetration through the body (bolts for the bumper reinforcement) the rust is starting to form. It is very minor, but still it can only get worse. So, I was thinking about pulling off all those rusty reinforcement pieces off, replacing them with new or treating them with something for rust, and also treating all the penetration points and screws as well. Has anyone else done something similar?

Diesel911 · #15 05-11-2008, 08:21 AM

If it is cold out the POR-15 is going to need a longer time to set-up.