Radiator repair?

My son has a small crack in his radiator near the filler neck. It is in a curved section but does not include the filler neck joint. The truck is
about ten years old. I'm wondering if this radiator should be replaced or repaired. If it should be repaired, should I braze a patch over it or drill the ends of the crack, grind the crack to a narrow slot and TIG-braze filler into it. I am familiar with brazing, etc., but the material is pretty thin, and I am wondering why this failure would occur in a non-stressed area.
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Larry Bailey
Illegitimi non carborundum
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Repair/replace has a lot to do with funds available.
If money is no object or dealing with radiator failure/towing is a dire fate your son does not want to face, then replacement probably offers a bit more peace of mind - but a good repair will hold up for years. Of course, if the radiator has not frozen or had something dropped on it (or hit it - like a stone off the road?) failure after only 10 years is a pretty poor sign - has the antifreeze been changed every couple of years?
I've soldered radiators back together (solder is the repair method I'd suggest, and at that you have to be pretty meticulious). Brazing sounds like a good recipe for a much bigger hole in the radiator - but you might be better at brazing really thin brass than I am.
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Cats, Coffee, Chocolate...vices to live by

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Low temperature solder and a propane torch are your best bets. Scrub the area clean with some steel wool and use low heat to flow solder into the crack.
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If the tank and cores are copper, low temp solder with a good acid based flux will do it up easily. But beware, there are a lot of late model vehicles with plastic end caps and/or aluminum cores that are essentially non repairable.
For a copper radiator, my local radiator shop charges about $50 to remove the tanks, run a rod though the tubes, solder it back together, leak test, and paint it black for best heat transfer. Hard to even think about doing it yourself.
cheers.
LBailey wrote:

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Painting a radiator actually adds a layer of insulation between the heated water and the air.
All racing radiators come un-painted for maximum heat transfer.
Radiator shops paint radiators to make them look nice after being worked on. it gives the customer that little glow to know that something shiny has taken the place of a malfunctioning component.
Whenever I have a radiator worked on - for myself or a customer - I always specify "no paint", and the radiator shop is happy to comply.
Bob Paulin - R.A.C.E. Chassis Analysis Services
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Assuming the radiator is repairable by you I would first make sure that the rest of it is not ready to fall apart. Radiators are much thinner than they used to be to ensure better heat transfer (I read a big dissertation on that somewhere) and I think the use of aluminum was tied into the scientific argument which surprised me since I thought it was so the @#$%#$# could do it cheaper.
Also, with aluminum heads etc if the radiator lets go and severely overheats the engine the rad replacement cost will look pretty cheap in comparison.
Billh

drill
filler
thin,
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Thanks for your replies. I made the small crack into a couple of bigger holes (grin) and then soldered a patch over that which held for the ten mile drive to buy beer for the admiration phase of the project. After that my wife told me that the cooling system was covered under the extended warranty that she had purchased with the vehicle. I was glad I had the beer.
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Larry Bailey
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Check out SilFos rods for the solder repair I have done it with great sucess using this silver solder
Ben

drill
filler
thin,
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I know the job is a done deed but I got a chance to talk to the radiator man in the family today so I thought I'd pass on his advice. He said there are a couple of easy choices. First "he" would, since he works in a well stocked shop, walk over and get a new filler neck and solder it in with regular solder. He tells me that radiator shops stock and sell them to the public but auto parts stores won't (at least around here in Los Angeles). If number one is not an option, second he would silver solder it with no patch. That's it.
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