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

BodhiBenz1987 · #1 06-23-2013, 10:58 PM

Bodhi and I are having another existential crisis and I could use a little advice and/or encouragement. Or a lot of it.
The car has been going fantastic lately and I haven't really had to do anything but oil changes and an aux water pump swap. I was actually itching for a project so I decided to take off the passenger front fender and clean up some lumpy old rust repair on the fender itself. While I had it off I decided I might as well clean up the wheel well, where, with the fender off, I could spot some of what I thought was surface rust. I should know by now what to expect from "surface rust."

The pictures tell the story. Now I have a giant hole, plus the air cleaner mount is barely attached and the two front bolts that hole the wheel well lining on are gone (that's where the rust started, obviously). It is obvious to me patches need to be welded in. I have a part clip with the area of the big hole, but I'm not sure about the two rear areas because the mounting is different on the diesel.
I was wondering if anyone else has had an issue with rust in this area, and how did you deal with it? On the bright side, I am more motivated to learn to weld than ever, so maybe after seven years I can finally get over my fears and actually do it. It's kind of my white whale in terms of overcoming apprehensions. On the other hand I'm looking at the positioning of this job and getting overwhelmed. I think it would take me months to get to the skill level to attempt welding in the engine compartment, and I don't want my car out of commission that long. Could I rivet in a couple patches, POR the heck out of it, and come back to it when I reach that skill level? Or would that just be asking for worse rust?
If I did weld it ... I understand from previous advice and Googling that an arc welder would not be suitable for the job. I guess I need a MIG? I don't care if it's ugly but I don't want slag flying all over or to end up slicing the fender up. Also, would I want to weld smaller patches in at each rust point (assuming the metal between is OK ... I haven't scraped all the paint off yet), or just cut out that entire front area of the wheel well?
I guess those are kind of vague questions, but I'm really just fishing for what other people would do, and I know there's a lot of experience AND imagination on here.

I do realize a lot of you would just put the engine in a cleaner car, but I am not considering that as an option at this point. Too much of this car is too nice to do that.
Pictures:

pj67coll · #2 06-24-2013, 12:07 AM

I'm afraid I can't be of much help to you on the specifics of welding etc. But I will offer the following encouragement for what it's worth.

Assuming the metal between the holes is sound I believe new patches can be welded in place. I also think you have the capability to learn to weld. I am in a similar position to you with regards to it being something of a mental block for me. But you know what. Probably hundreds of thousands of people thruout history have learned to do it including some I know who simply taught themselves by reading up on it and doing it.

I'm sure with the collective wisdom and encouragement of folks on this forum you will be able to do it and if that car is otherwise as good as it seems I think it's worth doing.

- Peter.

Stretch · #3 06-24-2013, 01:17 AM

I've been in a similar position. I still haven't finished the job yet! But here's some information that might encourage you

http://www.peachparts.com/shopforum/body-repair-restoration/309677-fun-games-welding-sheet-metal-arc-welder-learning-weld.html

Once you've got the hang of your buzz box you'll then need to to start learning again on the car! Welding in different positions is a new skill.

Essentially welding is all about penetration - you want to have had enough fusion / melting through out the joint but not so much that you melt it all away.

If anything the job that you want to go and do on the car is ideal. There's lots of space to reach the area where you need to weld - though you need to remove that electrical wiring well away from the area you are going to fix.

The next problem you'll have is bashin' metal. You'll want to make some new pieces that fit I guess...

...if you leave great big gaps between new metal and old you'll struggle with any welder but particularly a stick welder to fill them.

Go to MetalMeet - for Metalshaping Enthusiasts & Professional Metalshapers for tips on how to shape and weld metal.

Maki · #4 06-24-2013, 01:40 AM

If I had rust like that, I would clean it out thoroughly with abrasives and chemicals like Naval Jelly. Then I'd apply multiple coats of POR-15 or a similar moisture-cure coating to rebuild the areas structurally. Cured POR-15 will certainly support an air filter housing -- I've used it to restore battery trays. In fact, I used it to rebuild a floor rust-out just forward of the rear subframe mount on my '82 300 TD. After 9 years it's still quite solid, with the support of the nylon fabric I got from the POR-15 folks. It didn't stop rust from progressing elsewhere, of course. And yes, I can't vouch for its structural strength in a collision.

DeliveryValve · #5 06-24-2013, 01:56 AM

Those of us who followed Bodhi's story through the years know how much this car means to you. With that said, you are most likely to find more rust surprises in the future, so it is time for you to invest in a good MIG welder setup and start practicing your welding skills on scrap metal. It seems you have time to practice and once you are happy with your ability to create, form and weld in patch metal, go to town on Bodhi. These new experiences will serve you for a lifetime and will keep Bodhi on the road for a long time.

.

charmalu · #6 06-24-2013, 03:18 AM

Body shops are a good source for metal to practice on. they always have bent fenders, hoods etc... they will gladly give you. better to burn holes in scrap pieces first to get your techniques down.

Some times the local Jr colleges have welding night courses.

Would a TIG welder be better on this thin sheet metal than a MIG welder?

Charlie

pawoSD · #7 06-24-2013, 07:31 AM

Is this the only rust on the vehicle? Or does the rest of the car have similar issues?

My 300SD is very rusty too...I've battled it over 10 years at this point and the car means a lot to me, but I finally decided that this summer is to be its last before retirement...

Graham · #8 06-24-2013, 08:47 AM

Quote:

Originally Posted by BodhiBenz1987

Could I rivet in a couple patches, POR the heck out of it, and come back to it when I reach that skill level? Or would that just be asking for worse rust?

I have been going through a similar, but probably much more extensive rust repair on my 85 300D. (It is documented in the Bodywork Forum)

The approach I chose, was to have structural metal weld repaired by a local shop. Non-structural repairs were left for me to complete and I am in middle of that process right now.

A rust hole that lets water in just needs to be closed up. Similarly, a hole around a bolt or screw hole just needs to be repaired in a way that it will accept and hold the bolt/screw.

POR15 (or in my case DOM16) work well as a resin for laying up fibreglass. Small holes can be easily repaired by laying up glass cloth on both sides of holes up to say 1 or 2" diameter. Larger than that, using a combination of a riveted or screwed in place patch along with POR will provide a sturdy repair.

How long will the POR repairs last? On my 72 350SL, I have a low section in the trunk that was completely rusted out - nothing but rust remained. I cleaned that out exposing the original undercoating. I laid up a fiberglass bottom for that section using POR as the resin. That was 21 years ago, and it is still perfect.

There are some repairs where POR/fiberglass is in my view preferable to welding. For example, where heat will damage other components or adjacent coatings.

Based on my current experience, I would recommend you check the hinge pockets - leaks there were likely the main cause of my firewall and floorpan rust.

Good Luck with it whatever you decide.

JamesDean · #9 06-24-2013, 12:54 PM

For most of those rust holes I would pop-rivet patch it. Thats non-structural area. I did a similar repair on my 300D a while ago.
http://www.peachparts.com/shopforum/diesel-discussion/326451-300d-2-5-rust-repair-some-areas-watch-out.html

I also have some more extensive welding work on my 300SD's..
http://www.peachparts.com/shopforum/body-repair-restoration/288453-300sd-rust-restoration-project.html

http://www.peachparts.com/shopforum/body-repair-restoration/304380-300sd-rust-restoration-project-2-a.html

Alastair · #10 06-24-2013, 01:14 PM

If you are going to buy a MIG--Dont skimp and get the cheapest thing out there.
Trouble with the cheapos is the wire-feed system often isnt up to the job, will jam, cause uneven wire feed (And horrible welds) as well as the quality of the torch and liner will give you issues.

For car-body welding, you'll need a MIG with a current range from 25A to say, 140A, and able to use 0.6 and 0.8mm wires. Its best to use an Argon based MIG welding-gas rather than the 'gassless' wires, as this gives a nicer (and for a newcomer) easier weld.
My MIG is a 'Cebora' Autostar 190, perhaps a little overkill for autobody work, but as its pretty robust is an easy machine to set and use.

Here-- MIG Welding Forum

is a MIG welding (and other types of welding) Forum that has tutorials etc to help a newcomer to welding and how to. There's loads of advice/help on there...

--Like everything, Practice makes perfect but the best tip I can give--Make sure the steel surfaces where the weld is to actually be laid down are as Spotless of rust and paint as possible--A few minutes with a grinder to polish up make a Huge difference to the finished welds....

JamesDean · #11 06-24-2013, 01:23 PM

Quote:

Originally Posted by Alastair

If you are going to buy a MIG--Dont skimp and get the cheapest thing out there.
Trouble with the cheapos is the wire-feed system often isnt up to the job, will jam, cause uneven wire feed (And horrible welds) as well as the quality of the torch and liner will give you issues.

For car-body welding, you'll need a MIG with a current range from 25A to say, 140A, and able to use 0.6 and 0.8mm wires. Its best to use an Argon based MIG welding-gas rather than the 'gassless' wires, as this gives a nicer (and for a newcomer) easier weld.
My MIG is a 'Cebora' Autostar 190, perhaps a little overkill for autobody work, but as its pretty robust is an easy machine to set and use.

Here-- MIG Welding Forum

is a MIG welding (and other types of welding) Forum that has tutorials etc to help a newcomer to welding and how to. There's loads of advice/help on there...

--Like everything, Practice makes perfect but the best tip I can give--Make sure the steel surfaces where the weld is to actually be laid down are as Spotless of rust and paint as possible--A few minutes with a grinder to polish up make a Huge difference to the finished welds....

I've had great luck with my little welder guy.

MIG Welder | MIG Welders | MIG Welding

I do not use the gassless wire stuff. I went out and bought a small tank. It was like $120 or something I think. Refills are only $25.

It did well enough on my dad's 300SD.

Diesel911 · #12 06-24-2013, 03:52 PM

Quote:

Originally Posted by JamesDean

I've had great luck with my little welder guy.

MIG Welder | MIG Welders | MIG Welding

I do not use the gassless wire stuff. I went out and bought a small tank. It was like $120 or something I think. Refills are only $25.

It did well enough on my dad's 300SD.

The Tank refills will be cheap until the Tank needs to be pressure checked. That is done about every 5 years. I don't know what the pressure test will cost that will cost.

Also if you are taking a Tank back to be refilled be sure to look up the meaning of the Code Stamping Date on the Tank on the internet so they don't stick you with the Pressure Test charge when the Tank is still with in the time limit.

JamesDean · #13 06-24-2013, 03:56 PM

Quote:

Originally Posted by Diesel911

The Tank refills will be cheap until the Tank needs to be pressure checked. That is done about every 5 years. I don't know what the pressure test will cost that will cost.

Also if you are taking a Tank back to be refilled be sure to look up the meaning of the Code Stamping Date on the Tank on the internet so they don't stick you with the Pressure Test charge when the Tank is still with in the time limit.

Hrmm this is interesting. I think I've only refilled it about a half dozen times so far. Next time I'm there I'll inquire.

BodhiBenz1987 · #14 06-24-2013, 10:18 PM

Thanks so much, guys. Seeing other people's projects really helps both informatively and morale-wise. I think my plan of attack for this particular problem will be in two steps ... for the short run, so I can drive it, I will rivet in a sheet-metal patch on the large hole like JamesDean did, and just POR15-coat everything. For the long run, I will start working on welding. I'm a little worried about the equipment cost since I'm unemployed, but I'm keeping in mind all the value it would give me to have this skill at my disposal. I am going to poke around locally and see if someone has a used MIG setup, or one I could borrow ... my brother in law seems to be really good at finding auctions where you can get various shop equipment, so I'll ask him. In the meantime all the links you guys have supplied will keep me busy.

Also surely it wouldn't hurt to practice on the arc welder I already have. At the very least it would get me over the initial hurdle of the intimidation of welding in general.
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? A plasma cutter is not in my budget. I'm wondering if I should use that for my rivet patch, or save it for when I am ready to weld in a permanent repair.

gerkebi · #15 06-24-2013, 10:43 PM

Cut out from a parts car is preferable. IMO you need a buddy that can weld and learn from him/her. You definitely have the aptitude and attitude to learn welding. Maybe a tech school nearby? Good luck!