Thoughts on surface rust and pitting

[jenkins71]

Hi guys, I am fixing to paint the engine bay of my 71 Charger.
There is very little rust, but some areas of surface rust and some pitted areas.
What would you recommend as far as neutralizing the rust and filling the pitted areas before another coat of paint? I will be doing the paint myself with a Preval Sprayer.

Also, the very worst areas are these two spots on my firewall where the pitting has lead to a couple holes. I don't have the time or money to replace the sheet metal, but what would you guys recommend for stopping the rust in its tracks, and then filling the small holes? (Fiberglass from the interior-side perhaps?)

 

[eldubb440]

i would sandblast those spots, epoxy prime, fill the holes with some sort of 2 part epoxy then a little filler on top, reprime

 

[dvw]

Sandblast, metal prep (very important), Epoxy prime. Then I've used All Metal. I used it in my tailpanel for my Volare when it was painted in 1986 to fill some holes. It still looks fine today.
http://www.amazon.com/Metal-Filler-Putty-Quart-metal/dp/B00KYHCZNY
Doug

 

[65-440]

CLEAN ...ospho ,CLEAN.. then fill with all-metal, CLEAN .. ...etch prime ...... CLEAN CLEAN CLEAN !!!!

 

[jenkins71]

I don't have access to a sandblaster.... Can I just sand it down?

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And will All Metal fill dime-sized holes?

 

[flypaper]

I don't have access to a sandblaster.... Can I just sand it down?

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And will All Metal fill dime-sized holes?

you could wire wheel it all and use chemicals if you really had to
blasting is the preferred/best method
the filler is for pits and small stuff ,not larger sized holes
you might get away with it but
welding in a patch is preferred for that
things like this can come back to bite you in the ***
in the future.
even with blasting i would at least try to ospho up that seam
from the inside letting it seep thru as much as i could.

 

[65-440]

I don't have access to a sandblaster.... Can I just sand it down?

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And will All Metal fill dime-sized holes?

Yes it sure will. Just be sure to prep the metal first, wire wheel as much as possible and try to recess the holes before filling. All metal is good ****. Little advise, do not let it fully cure Before trying to sand down, it dries very hard! Start sanding it as soon as it starts to set up, will make life much easier! Don't be afraid to sand Down and apply a 2nd coat if needed. Great thing about that stuff is you don't need to glob it on, usually a thin coat will do.

 

[jenkins71]

Can someone explain "ospho"? Is that like Naval Jelly?

 

[flypaper]

ospho is a liquid rust converter
it will turn the rust into a paintable surface

http://www.ebay.com/itm/OSPHOQ-OSPH...452?pt=LH_DefaultDomain_0&hash=item418b17b324

 

[RGAZ]

Here is another option:

Blast to clean away rust. (can use a hand-held one from Harbor freight).

MIG weld against a copper back to fill the holes (low-heat, slow, 0.030" or smaller wire, less is more). A nice large piece of copper behind the panel (two man job and the copper gets very hot) with small weld plug holes to fill.

Then blend welds down GENTLY with a flap disc.

Treat rust with Rust Converter and epoxy prime and smooth with all-metal if needed.

If you get good with the MIG and the Copper you can fill small holes pretty well. make sure you get to some good metal though and not recommended if its really swiss cheese. You will be welding forever.

Another option to consider.

Randy

 

[jenkins71]

Good advice guys, thanks.

I went to the Auto Body Supply store to pick up a couple things. They didn't have Ospho, but I got SEM Rust Mort, which is supposed to be pretty good. SEM has good stuff. I also got a can of All-Metal and a can of weld-thru primer, which is for another project and was $35 for a rattle can!

I asked about the epoxy primer, and the guy said you can't buy it in a rattle can as it needs two parts to be mixed to work. I don't have a spray machine, so I won't be going that route, but I could do it in a Preval sprayer... what is so great about epoxy primer Vs regular primer?

Thanks

 

[flypaper]

epoxy is 2 parts when mixed together
you are getting a chemical reaction helping to cure the primer
making it as tough as nails
the best foundation to start with.

if your stuck on spray bombs
eastwood sells epoxy primer in a spray bomb.. it is pricey
its a one shot deal,once you activate it the can is shot
after a short period of time so use it all or lose it.
rust mort is a good product ,i have used it before
also if you are not blasting,
get a large wire wheel in a variable speed angle grinder to clean up that rust.
a wire wheel in a drill is a waste of time and it won't clean it up enough.
don't forget the goggles,the grinder will tear up wheels fast.
i saw a thread once where this guy over the winter
wire wheeled the whole underside of his car with a angle grinder
and it looked like brand new.

 

[Photon440]

Jenkins71, tell your body shop guy to get with the times. You can get two part epoxy in aerosol form. Like flypaper said, get it as Eastwood, or just go online to Amazon
http://www.amazon.com/Spray-Epoxy-Primer-Paint-Aerosol/dp/B0043YP8EC

 

[jenkins71]

Here is another option:

Blast to clean away rust. (can use a hand-held one from Harbor freight).

MIG weld against a copper back to fill the holes (low-heat, slow, 0.030" or smaller wire, less is more). A nice large piece of copper behind the panel (two man job and the copper gets very hot) with small weld plug holes to fill.

Then blend welds down GENTLY with a flap disc.

Treat rust with Rust Converter and epoxy prime and smooth with all-metal if needed.

If you get good with the MIG and the Copper you can fill small holes pretty well. make sure you get to some good metal though and not recommended if its really swiss cheese. You will be welding forever.

Another option to consider.

Randy

Randy, what hand-held blaster are you referring to? I have a little 8 gallon compressor, would it work with that? Thanks!

 

[ma mopar nutz]

Here is another option:

Blast to clean away rust. (can use a hand-held one from Harbor freight).

MIG weld against a copper back to fill the holes (low-heat, slow, 0.030" or smaller wire, less is more). A nice large piece of copper behind the panel (two man job and the copper gets very hot) with small weld plug holes to fill.

Then blend welds down GENTLY with a flap disc.

Treat rust with Rust Converter and epoxy prime and smooth with all-metal if needed.

If you get good with the MIG and the Copper you can fill small holes pretty well. make sure you get to some good metal though and not recommended if its really swiss cheese. You will be welding forever.

Another option to consider.

Randy

:imho:
YUP THIS IS HOW I WOULD DO IT OR I MIGHT EVEN CUT OUT THAT REAL BAD SPOT ON THE SEAM AND PATCH IN A NEW PEICE !!:headbang:

 

[RGAZ]

There are many different kinds. mine is old school Husky brand. But they are Like this:

http://www.harborfreight.com/21-oz-hopper-gravity-feed-spot-blaster-gun-95793.html

and get the media from Tractor Supply/fleet farm/etc or somewhere local (don't use sand!!!). I use a cheap black diamond grit that is dirt cheap.

It just needs 90 psi. If the flow is too low you just get to wait for the compressor to catch up and it can take a while, but you are not doing this to make money. Its a small repair. It can do the job no problem. Just spray a bit, wait, spray a bit more, repeat etc.

Also, when you are done, I use the little blaster to do all kinds of little parts. Its messy so do it outside and be sure to wear a hood protector (or good blast sheild and head cover) or you will be cleaning grit out of every pore and hair folicle. LOL

I hope this helps.

Randy

 

[jenkins71]

THANK YOU RANDY! I never thought of that! I think I may go that route.

Damn..... I just left Harbor Freight too. I feel like I'm there every other day with this project!!! Gotta love it.

 

[747mopar]

There are many different kinds. mine is old school Husky brand. But they are Like this:

http://www.harborfreight.com/21-oz-hopper-gravity-feed-spot-blaster-gun-95793.html

and get the media from Tractor Supply/fleet farm/etc or somewhere local (don't use sand!!!). I use a cheap black diamond grit that is dirt cheap.

It just needs 90 psi. If the flow is too low you just get to wait for the compressor to catch up and it can take a while, but you are not doing this to make money. Its a small repair. It can do the job no problem. Just spray a bit, wait, spray a bit more, repeat etc.

Also, when you are done, I use the little blaster to do all kinds of little parts. Its messy so do it outside and be sure to wear a hood protector (or good blast sheild and head cover) or you will be cleaning grit out of every pore and hair folicle. LOL

I hope this helps.

Randy

He took the words right out of my mouth. They aren't worth a **** for blasting a whole car but you can't beat them for those little areas like your in pics. Good luck

 

[Donny]

Jenkins, these areas are very bad. Most of the methods listed will result in your chasing your tail. These areas must be media blasted. You have a lot more damage here than you think, you never know until you get it blasted. Trust me, I've done hundreds of cars and parts, and I know what I'm looking at. You will likely need to replace the entire firewall - why? Because it's not worth fixing, you'll have patches everywhere, and I sort of doubt you or your helpers will Butt weld patches in. You're going to have heat issues, so warping will be challenging. Copper spoon and welding the holes up will not work, the metal is too thin to render this sort of repair, plus, you'll tear it up more attempting to fill and repair in this manner. Good luck. Look at the pics I have at drblast.com

 

[jenkins71]

Jenkins, these areas are very bad. Most of the methods listed will result in your chasing your tail. These areas must be media blasted. You have a lot more damage here than you think, you never know until you get it blasted. Trust me, I've done hundreds of cars and parts, and I know what I'm looking at. You will likely need to replace the entire firewall - why? Because it's not worth fixing, you'll have patches everywhere, and I sort of doubt you or your helpers will Butt weld patches in. You're going to have heat issues, so warping will be challenging. Copper spoon and welding the holes up will not work, the metal is too thin to render this sort of repair, plus, you'll tear it up more attempting to fill and repair in this manner. Good luck. Look at the pics I have at drblast.com

Thanks for your words Donny, but I really can't afford to replace the whole firewall at the moment. I'm not sure about welding either. I think I will just neutralize the rust and cover up the damage as best I can.

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He took the words right out of my mouth. They aren't worth a **** for blasting a whole car but you can't beat them for those little areas like your in pics. Good luck

Hey man, did you use the Harbor Freight gun? It's on sale for $15 right now, but I hear the Eastwood one (which it's based off of) is way better, and is $60.