Bending aluminum tubing

jj14u2c2 · Posted: Sat Jul 03, 2010 3:19 pm Post subject: Bending aluminum tubing

I'm putting a Suby engine in my Baja. Because the engine block is aluminum, I'm using 1.5" aluminum tube to run the coolant to the front. I wanted to bend the tubing so I can use fewer radiator hoses.

Does anyone know if it affects the integrity of the tubing if I bend it? I don't want to put a weak spot in it.

tripicana · Posted: Sat Jul 03, 2010 4:51 pm Post subject:

im pretty sure aluminum needs to be mandral bent...$$$

i dont think the same bender for steel tube will work with aluminum. but then again, a coolant system doesn't see that high of pressures, so it may work?
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drmiller100 · Posted: Sat Jul 03, 2010 7:46 pm Post subject:

1 inch is probably plenty, and you can use aluminum conduit if you want.

if you use aluminum, they make simple conduit benders.

also, an aluminum radiator mounted in the back above the engine is probably plenty of cooling...

Stoned_Elvis · Posted: Sat Jul 03, 2010 8:23 pm Post subject:

how about filling it with sand when you bend it.

Dale M. · Posted: Sun Jul 04, 2010 8:03 am Post subject:

I would use tubing that is same diameter of engine and radiator inlets and outlets....

A full mandrel bend will be great but radius will be large.....

I would at least try to have tubing bent by local fab shop as they will probably have proper dies and experience....

If the aluminum tubing idea does not work, look at premade up radiator hoses, some time something with a few factory turns (from some other application car/truck) may adapt with minimum of joints...

Dale
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jj14u2c2 · Posted: Sun Jul 04, 2010 8:29 am Post subject: tubing

Thanks for the input guys. I agree with Dale that the inlet and tubing size needs to be the same, so the volume of fluid is correct. Fortunatly I know the guys at my local NAPA well and they will let me go thru their radiator hose stock to find what I need. I'm just going to bend up some welding wire from the MIG for a mock up and use that to find good shaped hose for the various bends and joints.

Skidmark · Posted: Sun Jul 04, 2010 8:58 am Post subject:

I tried to bend some aluminum tubing with my low buck bender. Failed miserably... thin wall aluminum tubing will wrinkle on the inside of the radius without a mandrel. I think the radiator hose bends are your most economical option. Finding a tube bending company with the right size mandrels to do just a handful of bends will be expensive. The cost to set up the machine will raise the piece price too high. All fab shops make their money on volume, which makes small runs not very cost effective (I know, I run a fab shop).

I ended up using some 45 degree hose pieces and a straight length of aluminum tube for one of my radiator lines. The second line was a more complicated routing, and ended up going with a piece of steel roll cage tubing bent to the right shape. I know the rust will be an issue, along with the dissimilar metals, etc. It just made it easier so I went with it anyway.

Steel line on the right side...

Image may have been reduced in size. Click image to view fullscreen.

Aluminum line on the left side

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jj14u2c2 · Posted: Sun Jul 04, 2010 9:18 am Post subject: Metals

Skidmark, when I researched this on some Suby sites, several people say that using steel will eventually do unrepairable davage to to the engine block. Electrolysis will eat up the block from the inside water jacket.

I'm far from being an expert on the matter but, I don't want to risk blowing my investment in an engine. I'm going to steer clear of copper of steel.

Russ Wolfe · Posted: Sun Jul 04, 2010 9:35 am Post subject:

The Vanagon used steel from the factory. And that is an aluminum engine.
The replacement aftermarket ones today are bent out of stainless.
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Skidmark · Posted: Sun Jul 04, 2010 9:49 am Post subject:

I did the same research. What it boils down to is how long will that take? How much would it actually shorten the lifespan of the motor? With junkyard motors (long blocks even) being pretty cheap I do not feel the corrosion issue will be a factor in the life of the car. When the time comes, this engine will be replaced with another one. Buy a good used motor, and swap all my goodies over to the new one. Besides, I change my coolant more often than normal people do, which will help keep that from happening as quick (I know it will not prevent it). Design compromises are something every baja owner needs to wrestle with at some point or another, and even more so with an engine conversion. Weigh all the good and bad points and make your own decision - it's all good!

In my opinion, the electrolysis issue will not happen quick enough to be a big factor in my situation. Your situation may differ, but that is up to you.
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drmiller100 · Posted: Sun Jul 04, 2010 10:05 am Post subject:

electrolysis requires an acid or base coolant.

flush the system every couple of years, and it can't take place.

Russ Wolfe · Posted: Sun Jul 04, 2010 10:34 am Post subject:

That was the big cure for the Wasserboxer leak problems. Proper anti-freeze, an change it regularly.
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bdkw1 · Posted: Sun Jul 04, 2010 12:20 pm Post subject:

I have bent 1.5" X .120 wall 6061 in My bender with good results. Anything thinner will want to wrinkle the inner wall. The other downside as mentioned earlier is the large radius. All the dies must be polished smooth and greased not to smear the tubing also...........

PhillipM · Posted: Mon Jul 05, 2010 4:07 am Post subject:

If you anneal the tubing beforehand it's pretty easy even with 6061, just remember if you're using a strain hardening alloy that you might have to anneal it more than once to complete a bend.

xirxious · Posted: Mon Jul 05, 2010 4:43 pm Post subject:

I built a 1" tube bender and we didn't have to heat it much. It was just two large discs that I used a 1" ballnose endmill to put a 1/2" groove along the edges. It worked pretty easy.

PhillipM · Posted: Tue Jul 06, 2010 2:10 pm Post subject:

Depends on the radius.

ZARJDR · Posted: Tue Jul 06, 2010 6:05 pm Post subject:

If you worry that electrolysis is going to be an issue, why not add some sacrificial zinc to your system somewhere? Works well on metal roofs and boat motors.
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