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I recently had a radiator cleaned, soldered, and pressure tested for leaks at a professional radiator repair shop. Is it practical to try and do this at home? Can anyone explain the above procedures in detail?
 

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I can't speak to the rest, but I bought a pressure tester which I have used. The Allante cooling system is pretty sensitive and subject to leaks (aluminum block), so for me, it was a good investment. Cost around $100.

Essentially, its a small handpump with a fitting that attaches to the radiator cap hole and inflates a diaphram to seal the hole, then it pressurizes the system. I found that draining the fluid first is a big help, because it takes a lot of pressure to drive fluid out of a pinhole, but air will escape easily and make a noticeable noise.

When I did this, I found I had a couple of leaks at the hose clamps. On the particular car I was using it for, its possible to get leakage between the water jacket and cylinder liner. If you pull the plugs, you can supposedly (I didn't have this problem) hear the hissing into the cylinder. Dont' know if this is applicable to other engines - depends on the design I suppose.

As far as the cooling system, I pressurized it and found something else to do for a couple hours. When I came back, the gauge hadn't moved (after I tightened all the hose clamps) so I figured I was good to go.

Probably more than you wanted to know...
 

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I haven't worked at a radiator shop. But, my dentist (of all people!) worked for Ford Motors (radiator repair} while he was attending the U of Detroit.

When I was confronted with the problem of needing a custom radiator for my 36 Terraplane. My dentist came to the rescue. He explained what I needed and the procedures.

I picked up a 55 gallon barrel and made a dunk tank, then devised a way to hang the radiator at any level in the tank.

I then cut my tank fillers from Hobby shop stock. I used a Chevy truck 4-core radiator core (had it). Mounted on it's side (tubes up and down). Then soldered on my Hudson top tank (with the home made adapters on it) Keeping all but the work area submerged in water. This draws the heat away from the tubes and keeps the solder where you want it.

I had to adjust the radiator for the correct height, so I cut the core off about three inches from the bottom tank. Then melted the solder and removed the tank, then the bottom tank base and pulled the tube stubs out. Re-tinned the tank base.

Probably the most difficult thing was straightening and de-burring the cut tube ends. They have to be perfect to fit back in the tank base. Time consuming. Re-tin and melt the base back on to the tubes. Making sure each tube gets soldered/sealed to the tank base.

With the tank base done, I then had to place the bottom tank outlet on the correct side. So I heated and pulled the old outlet tube out and made a filler. Then cut a new hole, hand flanged it. Then soldered in the old hose tube. Soldered the new tank to its base. Pressure test showed a couple of leaks and I had to repair them, but it was a great experience and I learned a lot about radiators and soldering in general.

The results being a custom 4 row core radiator (with internal cooler) for the Hudson. At a cost of less than $60.00 as opposed to the custom shops wanting over $500.00!!!
 

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I don't think I'd try anything like Bob did at home, but I've made plenty repairs. Most tanks are removable and the seams can be soldered with a propane torch easy enough. Soldering where the actual tubes go into the tank base would be tricky with a torch. A heavy duty soldering iron or gun is needed for repairs to that area. A wet towel over the tubes works okay when you're soldering on the tank, or just go a little at a time.

There's an easy way to find leaks -- use a bicycle tube and soapy water. Get a 20" bicycle tube and cut it in half opposite the valve stem. Slip the tube ends over the radiator hose fittings and put the cap on. Use a hand pump and attach to the tube. The system is only designed for under 20 psi, but 5-6 is enough to find leaks. This will tell you if the cap is sealing good too. Much cheaper than a fancy pump with plugs!
 

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Great info, what about internal cleaning?

Great information guys. I will give those ideas try on my next project.

What is the best way to clean the inside of a radiator? I tried the over the counter radiator cleaners at the parts stores with no success. The radiator I just had cleaned professionally still has white crust on the ends of the flutes inside the radiator. What is the solution?
 

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I tried the bicycle tube and found it lacked the ability to attain sufficient pressure. I do most of my soldering with the little butane torch like a Blazo. You can direct the heat better without melting the adjacent solder.
I also think Bobcrman's project would be a little ambitous for some of us, but I salute him for his ingenuity.
When making repairs, especially to GM radiators, you will find that they use some kind of solder you can't get yours to flow into very easy.
 
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