Welding Tips and Tricks

1929 American LaFrance fire engine alum top casting for the radiator is thinned from years of corrosion. To the point it has eaten holes all the way through.

Any idea what alloy it might be? I've talked to some fire truck owners but they know more about their trucks history than it's mechanics.

Does anyone have experience using 1000 series aluminum filler rod? From what I have read, 1000 alum has the best corrosion resistance without added treatments. Seems to be just what this part needs. Any tips for this particular alloy would be appreciated. (I haven't been able to find any comments on it's use)

This is a job I have volunteered to do for free for the local fire museum. It will be a good practice job as the welds don't have to be pretty as any welds on the outside will be ground and polished.

I think I am set as far as machines and materials......fancy smancy welder with too many knobs and buttons, argon, helium, I can get any other consumables you folks think might help. Good thing is, this is not a rush job and I hope to have a much steadier tig hand in the end.

One more thing, sandblasting sounds like a bad idea to clean the corrosion because of contamination. So I'm thinking I'll use my die grinder with a carbide bit made for alum. but they get gummed up if you don't use some sort of lube. (again, possible contamination) Any ideas for a lube that washes off easy? I do have some dirty alum I can test out your favorite cleaning recipies.

Oh, and I'm going to buy a new cord for my phone so hopefully, I can post some pics for you to enjoy.

Thanks in advance, Bill

In a radiator that old that is aluminum the corrosion was likely from someone using the wrong antifreeze in it. Since I'm sure the new owner will use the correct additives then future corrosion won't be an issue. That means I would pick a filler rod that matches well with the widest variety of parent metals if I didn't know what kind of base metal I had.

Sandblasting is probably too abrasive for an ali casting like this anyway as it tends to be fairly thin and soft, but you could have it blasted with walnut shells or if you want to prevent any blasting media contamination have it blasted with dry ice (CO2) which simply evaporates and is not too abrasive.

It is a good idea though to get any accumulated crud and oxidation off of the ali casting surface as this can be sources of continuing (pit-)corrosion of the material and future pinholes/leaks.

Using a carbide burr (for local weld-prep) that's made for soft material (usually bigger/coarser cutting ridges) and some plain 'ol WD40 works well on alu. The WD40 works a bit like a cutting fluid and keeps the chips from sticking to the burr and clogging it up. Easy to then soak in a degreaser and get it all out. Then finish with a good acetone wipe and let it dry.

As mentioned above.. The existing corrosion is probably caused by old coolant or even plain water that was used in the engine and the ali simply being consumed in the system by the galvanic reaction (especially if there's copper parts in there too..) as it's the least 'noble' of the metals in the cooling system and the water works as an electrolyte.

Once it's all repaired then a good flush/clean of the entire cooling system and a fill with a modern OAT based coolant/antifreeze should keep any further corrosion at bay as it's full of inhibitors that keep systems with different metals in them happy on modern cars.

Bye, Arno.

While this is no help to your weld issue, I'll mention that if the radiator is isolated from the frame by rubber mounts, it needs a ground wire. Grounding it to the frame will virtually eliminate galvanic corrosion. Odds are fair that it was grounded at one time with a galvanized steel braid that rotted away adding to the problem you're facing.

Steve S

Otto Nobedder wrote:While this is no help to your weld issue, I'll mention that if the radiator is isolated from the frame by rubber mounts, it needs a ground wire. Grounding it to the frame will virtually eliminate galvanic corrosion. Odds are fair that it was grounded at one time with a galvanized steel braid that rotted away adding to the problem you're facing.

Steve S

Good tip and it works well!

Hopefully it will not be too thin as that will turn this into a nightmare repair depending on your alum welding experience. You can also clean the alum with an acid solution if needed, most local welding supply houses have it.

I would personally stay AWAY from sandblasting if for no other reason than to avoid getting the media inside. As for welding it... This might be stupid to say but maybe some Hastelloy W? That stuff is frekin amazing and welds pretty much anything. That or an aluminum filler that is extremely versatile. For cleaning I would try to get a thin vacuum hose inside it up close to the corroded spot and then get one of those wheels for a die grinder designed for aluminum or stainless and then scrub with acetone after. Just my .02. Best of luck and let us know how it turns out.

thatoneguy wrote: As for welding it... This might be stupid to say but maybe some Hastelloy W?

Someone correct me if I'm wrong but hastelloy w is just er312 isn't it? I love it too but I don't think that is going to stick to any aluminum alloy.

-Sandow

Sandow wrote:

thatoneguy wrote: As for welding it... This might be stupid to say but maybe some Hastelloy W?

Someone correct me if I'm wrong but hastelloy w is just er312 isn't it? I love it too but I don't think that is going to stick to any aluminum alloy.

-Sandow

Well, no it isn't the same but it still won't work on aluminum lol. Here is a composition chart for them.

https://docs.google.com/spreadsheets/d/ ... edit#gid=0

-Sandow

I welded a scrap old aluminum water pump one time,and I had to grind out a crack with a carbide bur, and I used ivory dish soap as a lube, worked very well, and a few shots with boiling water and it was clean, then add an acetone wipe down, it welded pretty good. I can not remember for the life of me what wire I used on it, and I went, and looked , and I don't have any more of it.

Sandow wrote:

thatoneguy wrote: As for welding it... This might be stupid to say but maybe some Hastelloy W?

Someone correct me if I'm wrong but hastelloy w is just er312 isn't it? I love it too but I don't think that is going to stick to any aluminum alloy.

-Sandow

It probably wasn't right but I've welded aluminum (not sure what it was) with Hast W and its still holding strong to this day. IDK why it worked but oh well lol

Unless your very experienced & confident then trying to weld a virtually irreplaceable rare radiator that old & porous sounds like a bad idea - if I was doing it I'd heat it with a torch & clean several times to boil the worst contamination off - light prep on the edges of pin holes but not too much - then use " HTS 2000 " or similar aluminum braze type rod - it will stick to most alloys without risk of melting them & if the tank is really thin you could flash tin a coat all over - if the part shows you can DA it off flat - go fine enough it could even be polished - most times I had an old aluminum casting like a water pump or thermostat housing & lit up on it with Tig it burned off all the contamination & left either Swiss cheese or just blobs of snot !