More existential rust crises for Bodhi (and me) - Page 3 - PeachParts Mercedes-Benz Forum

Stretch · #31 06-27-2013, 02:23 AM

Now GTG would mean pictures wouldn't it?

If so I vote GTG!

vstech · #32 06-27-2013, 09:12 AM

it might actually mean pictures, video and some writeups... I'll setup a cloud server for the fun...

DeliveryValve · #33 06-27-2013, 02:31 PM

Quote:

Originally Posted by BodhiBenz1987

....
A question on patches, whether it's riveted on or welded. Would it be better to use a cut out from a parts car, or fabricate one from clean new sheet metal? I have a front frame from a 1988 300E that looks mostly clean, but I have no idea how to cleanly cut out that section ... a sawzall then hand shears? ....

It really depends in the shape and size if the patch. New sheet metal would work well for flat areas and gentle contours. For areas that have a bends and contours that cannot be easily shaped, then a donor piece is required.

As far as cheap cutting tools, get a variety to be able to get the cut you need. Sawzaw is good to have, sheers are good to have.

Cut off tools are good to have. Like this.
120 Volt 3" High Speed Cut-Off Tool

I often use a Harbor Freight 4 1/2 in grinder with guard removed as cut off tool.

Having a GTG with vstech is a great offer. You definitely should to take him up on that offer.
.

daw_two · #34 06-27-2013, 02:44 PM

Quote:

Originally Posted by BodhiBenz1987

That's something to think about! You're near Charlotte, right? I might actually be down there a couple times this fall. I'll think over the logistics for a bit and PM you!

If it's going to be GTG, then let us all know. I might tow a trailer with the 1981 300D NA on it and buy an engine from vstech. While the rust is getting repaired on Bodhi, another w123 could come back to life.

BodhiBenz1987 · #35 07-22-2013, 01:56 AM

Little update with my temporary patch job ... which I put a lot more work into than planned ... so hopefully they'll actually last pretty long.

At least I learned a few things that will be useful when I weld too, like cutting sheetmetal, using seam sealer, and removing undercoating (one of the least fun things you can do when it's 95 degrees out). I ended up cutting out all four rusted areas with a body saw, to solid metal, then cleaning up with a dremel tool and with a few different wire wheel on a drill. POR15ed everything. I then cut out three pieces from a spare front clip, because they were shapes that were to tricky for my metalshaping skills and tools. The fourth piece I had to fabricate because that part of the parts car was rusted. I trimmed up those pieces with aviator snips to fit over the holes, then pop riveted them in place with JB Weld between. Then I added seam sealer, then painted it all with POR15. I messed up when cutting the parts car (I started with a sawzall and did not measure carefully enough) and ended up not quite covering the holes, which I fixed with small fiberglass patches and POR Putty. Stupid mistake. But I think it worked out fairly well anyway. I'm a little worried about the air cleaner mount bolt being lined up right ... I'll find out when I get it all back together. The only thing left I have to do is find the correct bolt to run through the fabricated patch to afix the wheel well plastic liner to.
One question: Do I need to topcoat the POR15? Not going to see much UV in that location. I was thinking of painting it white, but not sure what to use that I can just paint on. Now I'm just thinking I'll leave the POR15.
Here are some pictures, if anyone is curious. Not pretty, but it doesn't matter.

BodhiBenz1987 · #36 07-22-2013, 01:58 AM

More pictures.

rs899 · #37 07-22-2013, 07:36 AM

I think it may be too late to topcoat the POR-15 now anyway. It works best to do that while the stuff is still tacky, maybe 2 hours from putting it down ( or 5 minutes in FL)

DeliveryValve · #38 07-22-2013, 07:40 AM

Nice job so far. The work you did, you may consider this also a permanent repair.

You can leave POR15 that way. But if you wish to paint it, I would suggest roughing it up with 600 grit sand paper and then using the POR15 Tie Coat Primer so you can use what ever top coat paint you want to use.

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Maki · #39 07-22-2013, 10:38 AM

+1 on the Tie Coat Primer. It works very well.

pj67coll · #40 07-22-2013, 11:07 AM

Very good job. Well done. That's more than I've ever managed to do. I think you should paint it too. It will look really good then.

- Peter.

Stretch · #41 07-22-2013, 11:12 AM

Here in Holland it took over a week for that tie coat primer to set - make sure it is warm where you are before you use it. If you paint over the top of it and it isn't dry the upper coats (as many as 10!) will go all crinkly. POR15 also do a self etch primer that sticks to other surfaces - the tie coat primer doesn't stick well to anything other than POR15 in my experience.

Graham · #42 07-22-2013, 11:40 AM

If you can get at the POR, roughening surface with 80 or 120 grit paper is all I have ever done and I have used POR for over 20 years. However, this is what POR says to do:

Quote:

TO TOPCOAT A FULLY CURED POR-15 SURFACE:
Wet sand with 600 grit until gloss is dull, then paint, or use POR-15 Tie-Coat Primer directly on the cured POR-15 surface, then topcoat as desired.NOTE: Never topcoat a POR-15 surface that hasn't dried, as this will ruin the coat already down.

Graham · #43 07-22-2013, 11:41 AM

If you can get at the POR, roughening surface with emery paper is all I have ever done and I have used POR for over 20 years. However, this is what POR says to do:

Quote:

TO TOPCOAT A FULLY CURED POR-15 SURFACE:
Wet sand with 600 grit until gloss is dull, then paint, or use POR-15 Tie-Coat Primer directly on the cured POR-15 surface, then topcoat as desired.NOTE: Never topcoat a POR-15 surface that hasn't dried, as this will ruin the coat already down.

JamesDean · #44 07-22-2013, 02:38 PM

You might want to invest in an angle grinder with a wire wheel attachment. It makes quick work of that undercoating! Your repairs look pretty decent actually! Hopefully with the coatings you've applied they'll stay that way for a good while.

This weekend I had to do some stuff on my 300D too. The wire wheel took less than 5 minutes per area to clean them up as pictured.

Thread:
http://www.peachparts.com/shopforum/diesel-discussion/341520-w124-drivers-rear-wheel-well-rust-cause.html

Pics:
W124 300D Rust Repair 7-20-13 - Imgur

JHZR2 · #45 07-22-2013, 11:06 PM

Ugh, rust is the worst. The only thing to do is to cut it out and I would personally not leave small patches of old metal interspersed with new metal. I trust the welded joints the least compared to new metal and old sound metal. I would rather see a cut out completely and replaced with good metal, and then the entire peace be thoroughly rustproof in front and behind to protect both the new metal on metal and the weld itself.

I'm personally of the mind that unless you really want to take on doing welding take the bit in the future, but you're better off leaving it to somebody who will take on the job I have the right equipment experience and tools to do it. You may well spend as much in getting good tools to do the job right as someone would charge to do it properly once and for all.

A lot of shops don't want to take on rust work though, because where there's some there's usually more, a lot of jobs are very difficult to do. Plus it is tough if they offer a warranty because an old rusted car likely will have another claim.

What I would do is find a local trade or vocational school, probably at a community college or somesuch place, where the purpose is learning, the costs are fairly low, and because the efforts are graded there's a good chance of having it overseen and a very good job being done. I'm not saying there's no risk to this approach, but I think that you will have a better chance of getting a good and complete job done with the materials and processes used that you desire.

So I get an opportunity like that and specify that you want to overseeing the rustproofing on the back of the panel prior to painting the whole thing completely. Because of the nature of the capabilities of such a school, they should be able to do the metalwork and then do all the paint blending for you making it easy.

Good luck!