where did I go wrong (rust)?

[doofus]

Some of you might of seen my first posts on this forum in 2007/2008 when I purchased and fixed some fairly nasty rust on an otherwise solid HJ47 troopy.
https://forum.ih8mud.com/fj45-owners-club/213568-hj47-troopy-completed.html

Well the rust around the pieces I repaired came back with a vengance!

I will need to start complete repairs again and remove the roof etc. Before I start I want to work out what I did wrong so I won't do it again.

My previous method was to cut and grind bad steel away, make a new piece to fit out of 0.8mm sheet, weld it in, etch with acid cleaner, paint with por15, the smear with polyfiller bog, sand back and then finally paint. See the pics in the thread above. I should comment that this was the first time I had attempted any rust repair or body repair in genereal.

My current thinking is that the bog and outer paint were porous to moisture and rust was able to start to get in around the por15. But I thought the por15 would of stopped it!!! I am generally not happy with that product and will be looking at perhaps rust bullet this time around.

Any Ideas why my rust repairs were so short lived?

 

[cult45]

My first thought is moisture. At any stage during the repair/repainting process did any moisture get within cooee of it? I did a BJ42 frame-off in 2000 with major rust repairs [also my first body work] and I saw the truck by chance 12 months ago and it was still solid, just a few bubbles here and there. SO you can be a total newb and pull it off, you just gotta source the cause of your rust return.

Bog and primer are both porous. If they get any moisture near them at all [bare metal included] then you're allowing the potentiality for rust coming back.

Unless you've been beach-driving every day since then?

 

[alberta mac]

Rust ... I would look at the route water will travel and make sure it can exit.
Sounds like you did take precautions... hhhmmm ?
If I were using steel I would do as you did with por or other and then after fab then oil spray the area possibly drilling some holes to apply the oil periodically.
I did my bj42 in stainless 304 and have done some work in steel also on other cruisers so leaving bare metal as we know is not an option. Make sure your spray is not going on oily metal.
The metal we buy has a thin coating of oil and can be welded.
When rebuilding you may want to clean the metal with a grinder or sand blast then weld and pant/ por / other.
any pics ? of the areas you are revisiting ?

Cheers
JMac

 

[Henry James the 47th]

Same thing happened on my truck after the 600 hours I put in welding. I think that the rust in the seams comes back no matter what, and areas on the inside of panels where you have welded and couldn't physically get at the inside, will have been bare metal and therefore re-rust quickly. Also, there are places where you cut out rusty metal but may not, for various reasons, cut enough of the rusted metal out, and the rust creeps back in short order. I'm thinking of the rocker panels where they meet the door sill for instance. Also, rusted panels, after being blasted back down to bare metal are often so thin that they are weak and hard to weld on without burning through.

I think the rust in the seams will come back unless you cut out every single spot weld, separate every panel, and media blast the rusty seam metal. You can cover it up, try to work rust killing chemicals in there, etc., and it still comes back.

Now that you've done all the weld repairs, you are faced with the metal in those areas being hardened from all the heat, and re-welding too close by may open up another can of worms.

After all the welding is done, at the very least you need to go over every area, making sure it is completely free of rust before primering. Getting rust encapsulator into every nook and cranny with a wand (which may mean drilling access holes into certain areas, or getting the tub dunked in rust killing solution, or zinc treatment after all the welding would be worth the trouble and cost. Sounds a bit drastic, I know.

I'm seriously looking at getting a stainless or fiberglass tub. I think steel will always rust, no matter what, and I for one don't really enjoy months of welding and body work. If you live in a desert, and the truck never sees salty roads, that is a big plus. If not, the steel will rust.

 

[toomanytoyzz]

Post up some pics of where it is starting to (re)rust. My guess is either the panels didn't have all the rust removed before you started the repair or water/moisture is finding its way in under your repairs and starting the process all over agan. When you use body filler in excess it can act like a sponge when water contaminates it. Once you start seeing the bubbles it's a probably gonna have to be redone. Time to get the tools out again.

My advice to you would be to completely tear down the panels and have them media blasted or acid dipped. Acid dipping will get the panels completely down to bare metal on the inside as well as out while media blasting will only get to the areas the nozzle can. Both methods definitely have their + and -'s. With dipping you will have to get primer on the bare metal or else it will obviously rust. Blasting can leave rusted areas untouched if the nozzle/media can't reach. Either way will work 1000x's better than a grinder and some metal ready on a panel.

I would also suggest completely welding up the sections you repair. If any portions are not they will rust even with body filler completely covering it.

 

[alberta mac]

I personally hate revisiting a job I did and thats why I rebuilt with stainless.
However my 45 I did in steel so I there for am now in the same boat in a few years possibly.
I sprayed undercoat everywhere I could when I finished welding.
I think spending a weekend removing the tub and sending it out to get hot dip galvanized would be Awesome then bring it back and por/ duroliner the whole thing folowed by finishing paint.
*** If you are going to replace metal go with 16ga. where 18ga. was used.
Make some areas stronger.

Cheers

 

[Henry James the 47th]

Got any pics of your stainless body work? How did you find it to work with?