Question about stick welding aluminium

aussiebushman · May 14, 2016

When a thread was stripped in an aluminium engine block, I tried to drill it out for a larger bolt - inevitably, the drill wandered off-center and went through the outside of the casting so now it leaks coolant. The engine is still in the vehicle and I live 40 miles from the nearest repair shop so a DIY fix is the only answer. This is my old unregistered "bush basher" It is very necessary around the farm but not worth spending heaps of money - it just needs to go again

I made an aluminium plug in the lathe and it fits OK but brazing was hopeless - just can't get enough heat in to to make the aluminium rod flow into the joint. My current plan is to bond the plug in with dynagrip - a high temperature bog - necessary because the hole is right above the exhaust manifold and I doubt "ordinary" thickened epoxy will withstand the heat.

Can anyone suggest whether putting a shorter plug into the hole then filling to the top with the stick welder might be better?

Monarchist · May 14, 2016

aussiebushman said:
When a thread was stripped in an aluminium engine block, I tried to drill it out for a larger bolt - inevitably, the drill wandered off-center and went through the outside of the casting so now it leaks coolant. The engine is still in the vehicle and I live 40 miles from the nearest repair shop so a DIY fix is the only answer. This is my old unregistered "bush basher" It is very necessary around the farm but not worth spending heaps of money - it just needs to go again

I made an aluminium plug in the lathe and it fits OK but brazing was hopeless - just can't get enough heat in to to make the aluminium rod flow into the joint. My current plan is to bond the plug in with dynagrip - a high temperature bog - necessary because the hole is right above the exhaust manifold and I doubt "ordinary" thickened epoxy will withstand the heat.

Can anyone suggest whether putting a shorter plug into the hole then filling to the top with the stick welder might be better?

You don't have the needed equipment locally to do a lasting repair. Odds are you can damage it far worse than it is now. Not a new situation for any of us.

Coolant leaks more slowly if yah leave the rad cap on the unpressurized notch. You knew that.

Jam something 'temporary' that'll stand the heat up against the leak it to slow it down. Wire and scrap metal for bracing. Aluminium kitchen foil pounded to shape. Stainless hose clamps around that handy exhaust manifold. Wotever fits and won't melt or catch fire in less than two hours run-time. If ever.

Dasn't have be pretty. Has to 'help' get you 40 miles. Once only.

Carry jugs enough of water with yah. Stop and check coolant level now and then.

IOW baby the bitch those 40 miles to where they DO have the resources to make a better 'patch', even if it IS but a patch.

"Dynagrip" is probably not going to make the next Pilgrim's job easy, and he may charge you extra for the insult.

Upgrade yerself from stick-only to TiG or MiG 'in addition' some other day if you wants greater independence from High Street.

Take the few extra minutes to drill a smaller pilot hole next time, too.
MUCH smaller.

If it goes walkabout, run some wire down into it and try harder. Get it right, THEN yah uses the larger drill 'coz it knows where to go.

Bill

moonlight machine · May 14, 2016

You will not get enough heat to do any sort of welding without stripping it down. Then when you weld it it will pull and move around a lot as it cools off. I have never seen stick arc aluminum rod that was any good. Try and get some thread in the block, thread a plug in with your bog. It's the only chance you have as I see it.

Clive603 · May 14, 2016

Wonder if you can get things hot enough in a block to use that weird "Lumiweld", or whatever they call it now, stuff which locally depresses the melting point of the aluminium to form the bond. Access might be a problem. Maybe fill the whole hole up and re-drill from scratch or put a half diameter (ish) piece of alloy in the hole opposite the crack and fill the gap.

The one time I used it myself the bond seemed effective and the filled section well hard enough to drill and tap. I have a feeling that the show demonstrator I bought it from had a sample of a failed tapped hole running into a gasket which had been filled and re-tapped. As I recall things it was claimed that no subsequent machining was needed as the affected area on the gasket face was too small to cause sealing problems. Probably looked OK by eye as I did buy the stuff. A long time ago tho', 35 plus years so memory may not be accurate!

One time I did a similar job I tapped oversize, loctited a plug in and re-tapped. BSP threads were probably involved as being good for in-between sizes and odds are the stud was double diameter with a wrong thread going down into the repair. Most likely the bottom few threads were left tapered so as to give some expansion when the stud went in to help hold things.

Clive

L Vanice · May 14, 2016

Clive603 said:
Wonder if you can get things hot enough in a block to use that weird "Lumiweld", or whatever they call it now, stuff which locally depresses the melting point of the aluminium to form the bond. Access might be a problem. Maybe fill the whole hole up and re-drill from scratch or put a half diameter (ish) piece of alloy in the hole opposite the crack and fill the gap.

The one time I used it myself the bond seemed effective and the filled section well hard enough to drill and tap. I have a feeling that the show demonstrator I bought it from had a sample of a failed tapped hole running into a gasket which had been filled and re-tapped. As I recall things it was claimed that no subsequent machining was needed as the affected area on the gasket face was too small to cause sealing problems. Probably looked OK by eye as I did buy the stuff. A long time ago tho', 35 plus years so memory may not be accurate!

One time I did a similar job I tapped oversize, loctited a plug in and re-tapped. BSP threads were probably involved as being good for in-between sizes and odds are the stud was double diameter with a wrong thread going down into the repair. Most likely the bottom few threads were left tapered so as to give some expansion when the stud went in to help hold things.

Clive

I bought some sticks of "Mad Dog Weld" (seriously-I still have the package) at an antique tractor show maybe 35 years ago. I had the lab at work test it and found it is pure tin. I have used it a few times on broken cast aluminum and it does work very well. I use an air-acetylene (Presto-Lite) torch. The joint has to be encouraged to bond with the tin by wire brushing or steel picking the melted tin against the aluminum surface. It does not flow and bond like silver alloy on steel. Once the surface of the break, or a vee filed along a crack, is tinned, the gap can be filled in. The excess is easily smoothed with file, mill or sander. The repair is difficult to see, but is a little different color from the aluminum. The tin seems to be about as hard as common cast aluminum, so the joint strength is about the same as the parent metal.

Larry

stephen thomas · May 14, 2016

Used Lumiweld & acetylene torch to repair a former GF's radiator about 35 years ago. The relationship did not hold, but apparently the repair did, at least for a few more years that we were in touch.

Bought a Monkey Wards high freq unit for my AC/DC 250 stick welder some 40 years ago, and a later Linde clone TIG torch. Still works fine for my Al needs, including did some Pentagon work with it a decade or so ago. For casual use, only thing really missing from that set up, for an aircooled torch, is foot pedal control. But as others noted, you will have to strip the block, possibly brace/fixture it, and most likely need to do some machining on it afterwards if the weld is near a joint surface.

I once tried Al sticks for a heavy casting. Burned up a pound or 2 practicing and never did get fast or good enough to use them. Went back to heating with a torch and TIG'ing it. You won't like sticks at all if you have never tried it. And still gets back to needing to strip the block to do it well if at all.

I'd try threading a plug in the hole already made, with whatever goop is the best temp resistant. Then fashion a sheet aluminum heat shield onto the exhaust manifold, and pipe clamp it in place. Could even use 2 layers bent to form a slight separation.

Good luck!

smt

HuFlungDung · May 14, 2016

moonlight machine said:
You will not get enough heat to do any sort of welding without stripping it down. Then when you weld it it will pull and move around a lot as it cools off. I have never seen stick arc aluminum rod that was any good. Try and get some thread in the block, thread a plug in with your bog. It's the only chance you have as I see it.

Everybody should try welding aluminum with stick. It's like feeding limbs into a shredder.

johansen · May 14, 2016

I have a hard time believing a hole that leaks coolant will get hot enough that epoxy won't work.

Big B · May 14, 2016

Ir doesn't seem like the heat from the exhaust manifold would be a problem for a weld that is sealing up a water jacket. I wouldn't worry about it at all.

aussiebushman · May 14, 2016

Thanks guys - good advice as usual

The problems you mention about stick welding seem right-on. I agree that getting into the space without removing the engine and stripping the block make it highly impractical.

Comments about the water jacket keeping the temperature down are probably right but the hole is so close to the manifold my guess is that radiant heat alone could crack epoxy - the Dunagrip stuff is supposed to be good to 1300 c - it is probably similar to the "mad dog weld" you mention.

The picture shows the extent of the damage. This problem started with a stripped thread when I reinstalled the head and foolishly, I thought the head itself would act as a guide to drill the hole deeper to take a longer bolt - Big mistake.

I'll go with the option of inserting the turned aluminium plug I made into the hole all the way down and sealing it in with the Dynagrip. Once set into place, the aluminium plug can be center-punched, a pilot hole drilled then opened up and tapped for a new HT bolt. With the head now off. it will be easier to get the new one in square to the surface of the block. I'll go up 1/16 to a 1/2" UNC for which I now have the right taps

What do you think??

Alan

3t3d · May 14, 2016

Back when I used to race snowmobiles....
One of the engines had an exhaust port repaired with titanium epoxy.
It wasn't Close to the exhaust, it WAS the exhaust port...
Never had a hint of failure.
Don't know the source of the titanium putty.

Anyone else?

Now, granted, I don;t know how that could work for ahead bolt.
Maybe a threaded insert is a better idea at this point.
Can you make a better "guide bushing" than the head was that you tried?
Any piece of scrap might do it, it can be held in place with the other head bolts.
Good Luck.

HuFlungDung · May 14, 2016

Devcon made titanium filled putty.

snowshooze · May 14, 2016

I have been able to make beautiful weld deposits on heavier sections of Aluminum with the stick.
But, to really make it weld, a very good pre-heat is the key.
Otherwise, you wind up with a mess.
Take the oxy-acetelene torch, light it.
Leave the oxygen off.
Cover the weld area in soot with the flame.
Now, turn on the oxy for a neutral flame, and heat the part until the soot burns off.
Weld immediately.
You will be pleased.

Monarchist · May 14, 2016

aussiebushman said:
What do you think??

Alan

I think.. that unless you can rig something that positions and guides the drill at least as well as a 'mag' drill could do, you will still not have the tapped-hole's axis and position where the head, head-bolt, and their stress pattern expects it to be.

Fixturing for that dasn't have to be all metal, but you need something that will hold better than just best wishes from afar, Mark One Eyeball, and sorely tired muscles in an awkward position can do..

And that presumes you get a good enough fill to be near-as-dammit at a 'virgin block' starting point.

Bill

aussiebushman · May 15, 2016

Working on the time-proven practice of never throwing anything out that might be useful, I found some LOCTITE cold weld compound on the shelf here and using that and the aluminium plug I had made, got a very secure insert bonded into the hole. When the Dynagrip arrives I'll bog around the outside of the repair to reinforce it.

Regarding re-drilling for the bolt, it is an excellent suggestion to make up a jig.

Can you make a better "guide bushing" than the head was that you tried? Any piece of scrap might do it, it can be held in place with the other head bolts

Thanks and regards

Alan

Monarchist · May 15, 2016

aussiebushman said:
Regarding re-drilling for the bolt, it is an excellent suggestion to make up a jig.

That gets the start in a better place, even reduces walkabout. But if you are using a hand-held drill motor, you also need something to determine and hold the angle so it doesn't move or defeat the bushing. Lack of such was, after all, a part of how this came about as a problem, was it not?

Even wood plank fastened into a vee-trough that the drill body can be held against could help. Framing for that sort of 'helper' doesn't much have to go down inside the engine bay. Not unless you are using a close-coupled right-angle drilling head anyway.

Bill

DDoug · May 16, 2016

HuFlungDung said:
Everybody should try welding aluminum with stick. It's like feeding limbs into a shredder.

The description I heard was:
"It's like trying to shuck walnuts, in the dark, with a logsplitter"

magneticanomaly · May 18, 2016

Alas, however leak-free a glued-in piece of Al may be, and however accurately drilled and tapped, when you try to torque the new head-bolt it will pull out. You need either a fully-threaded plug in an oversize and off-center tapped hole. then drilled and tapped at right location, or fill the bad hole with fully-fused weld and re-drill etc.

moonlight machine · May 18, 2016

That block is junk, the only way you stand a chance of repairing it is to set the block up on a mill and bore the remainder of the head bolt hole and the other damage out. Go just enough bigger than the original hole that the head bolt will be in the insert you will have to make. Leave as much of the casting from the original thread boss as you can. Thread the hole and your insert. Make a sleeve for the head bolt hole in the head, OD to fit the head, ID to fit the tap drill for the head bolt threads. that way you can use the head for a drill fixture. Welding of any type will never work to hold the torque of a head bolt. Any type of weld for aluminum will be dead soft and will never hold threads.

Monarchist · May 18, 2016

digger doug said:
The description I heard was:
"It's like trying to shuck walnuts, in the dark, with a logsplitter"

Make that Hickory nuts, a rusty ball-pein hammer, each hand inside a smelly workboot for 'protection', and a committed willingness to go hungry most of the night, and yer on.

FUBAR of this sort, for the time spent - too much of it borderline torturous, and too little of it sane - most folk just scout another used engine, entire, and spend the time and money saved shagging or drinking beer.

OTOH 'most folk' are not a whole gee-whiz 40 miles out in the outback, so... might have just hauled it to town and had an experienced hand tell him it was .. basically scrap, regardless... by this point.

Araldite 'er up, diddle the valvetrain to convert to a motor one-tube-shy of a full set... and JFDWT?

Been done before.

Bill

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