A job I'm not looking forward to... - PeachParts Mercedes-Benz Forum

colincoon · #1 10-14-2009, 07:11 PM

Well, after sitting all summer in the shop (and outside) Norm's rock chips have bubbled and need to be treated. Honestly, I'm scared to do the job. I have the POR-15, body filler, primer, and paint, but just am afraid of messing it all up.

This is what I will be tackling:

I'm guessing body filler wont take care of the giant hole, but I will at least treat that.

Any tips after seeing those pictures? I am going to start on it this coming weekend. I know the procedure is to sand it down, eliminate all the rust, treat with por15, bondo it, prime it, paint it.

I'm just nervous about actually doing it and having a terminal mistake. Anything mechanical I can handle, not so much cosmetic =/

79Mercy · #2 10-14-2009, 07:28 PM

All I can say is good luck. I'll be doing the samething to my W115 prety soon, but the rust isn't as bad as that.

Be sure to take pictures as you progress.

TheDon · #3 10-14-2009, 07:38 PM

just clean it to bare metal and por-15 it.. You could fiberglass it after that to get the shape back

NoSparkNeeded · #4 10-14-2009, 07:41 PM

It all depends on the quality level you expect of the repair. Yes you could use filler on that hole, but to do it properly you would use a dremel or nibbler to excise all the rust. Just cut it away. Sand or grind to shiny metal around the edges. Then you would weld in
some metal with a mig. Prime the backside with POR or cold galvinize.
Look for a filler called "ALL METAL". I would use this filler even if you are not going to weld. Mix the filler and apply, shape with a "cheese grater" file and sand to shape, repeat as needed. Spray with high build 2 part primer, block sand, spray again, squirt a guide coat of flat black, block,
and finish sand with #400. Spray your topcoat. If you aren't going to weld, then do the same steps but use a fibreglass mat to back the hole.
Mix up your filler and saturate the mat with it. Press the mat from the back of the hole. Let it set up, then do your build up with filler in the same way, as if you welded. The fibreglass mat becomes your "metal" patch. If you are careful to remove all the rust, this type of patch has lasted a good long time for me, although since I am able, I always weld.

NoSparkNeeded · #5 10-14-2009, 07:52 PM

Some people "pickle" the metal with "metal prep". I only do this in cases
where I cannot really grind a reall solid shiny edge on the part I'm working on. I used to do this to everything metal I was finishing, but I only do it in certain cases now. Take a look at my gallery, there are before and after pics of the rust holes I fixed. No exactly a tutorial, but a good example of what you are facing. If you have questions as you go along just ask

.
This kind of body work is really annoying, but not that complex. Just a great deal of elbow grease and patience, and ugh sanding, sanding, sanding, dust and toxic materials,heh. You need a good little gravity feed
spraygun. If you have a local bodyshop supplier, they will be lots of help.

colincoon · #6 10-14-2009, 07:59 PM

^That was what I was thinking about doing. I can't weld, but fiberglass seems to work just as well (especially down there where nobody will see it). So pretty much soak the fiberglass in the bondo, apply to the back, let dry, and fill the hole via the opposite side until it's flush?

Might go with this for that hole.

Quote:

Originally Posted by TheDon

just clean it to bare metal and por-15 it.. You could fiberglass it after that to get the shape back

Wanna come over and help Saturday? I'd like to at least get the POR applied in all areas.

Thanks guys.

kingdoc1 · #7 10-14-2009, 08:08 PM

I think a small spot-sandblaster would work well for you if you have access to an air compressor. Sandblasting is a very effective way to remove all the rust and then you could treat with the Por-15. I think Harbor freight might have something reasonably priced.

colincoon · #8 10-14-2009, 08:11 PM

^I do have a small air compressor. I want to keep this as simple as possible though. However I don't mind the investment to kill the rust.

TheDon · #9 10-14-2009, 08:16 PM

Quote:

Originally Posted by colincoon

^That was what I was thinking about doing. I can't weld, but fiberglass seems to work just as well (especially down there where nobody will see it). So pretty much soak the fiberglass in the bondo, apply to the back, let dry, and fill the hole via the opposite side until it's flush?

Might go with this for that hole.

Wanna come over and help Saturday? I'd like to at least get the POR applied in all areas.

Thanks guys.

I work at 5 and have some work to do here

NoSparkNeeded · #10 10-14-2009, 08:18 PM

>>So pretty much soak the fiberglass in the bondo, apply to the back, let dry, and fill the hole via the opposite side until it's flush?

>>Might go with this for that hole.

That is the basic idea. I'd sure get the "All Metal" filler, not plain bondo.
Use the stiffer fibreglass mat. I take the mat, cut it to shape, mix up my filler QUICKLY, work it into the mat, really well, then stick it on the back of the hole, that you have PREPPED really well. Good clean metal behind for the patch.
Don't try at this point to do anything but secure the patch against clean metal. Shape with your subsequent filler applications. Some folks saturate
that first patch with liquid resin, but I've found the body filler to be better, IF you work it into the mat well. Expect to apply and sand off at least 3 times until you get the shape correct. I can do it in two applications now on simple shapes, but have been known to do several "put it on sand it too far" trying to get the shape perfect. VERY lightly
spray on just a light speckled coat of flat black spray can laquer as a guide coat to find your high and low spots when shaping.

>>>Wanna come over and help Saturday? I'd like to at least get the POR applied in all areas.

Hmm, I'd watch and give advise, help? Naw I hate sanding

.

tankowner · #11 10-14-2009, 08:24 PM

POR-15 might be a good idea, but from what I know of it, you should only apply it to rust, not cleaned bare metal. I know I have read reviews where it was applied to bare metal and it did not give the desired result (same area began rusting out again later). POR-15 is specifically made to be applied to rust - just make sure you follow the directions.