Once you crack the bung hole you usually need to sweat in a new one. If the radiator is rotting at the top where the tubes join the header then you may need to have it professionally assessed as trying to fix the tube header without some good training can lead to doing more harm than good.

if the tube is rotted at the header, it's time for a new radiator. Rotted tubes don't have the strength or enough material left to repair. Any competent radiator shop will tell you that

The old timer who taught me would cut back and lengthen rotted tubes if there were only a few at either side and the header was in relatively good shape. It depends on the extent of things. Of course back then labor costs were not what they are today and adding an another hour or so only put another $10 to the job and not $100 to $300 like it can today.

The main issue is the minor crack at the drain plug. The top connections are fine. Only a minor vapor on the passenger side of the rad (not near the rad cap). I think overall the rad is in pretty good shape. My approach will be to try to fix it myself and if I still have an issue then replace. There's no way I'd spend $100+ to get a rad shop to fix when even a new one is $189. Nothing related to fixing cars in Canada is <$100.

The best (worst?) one I ever had was a rattle near the muffler on our Nissan Sentra. Brought to Cdn Tire and they quoted me $1000+ to fix the rattle. Essentially they were going to replace all the heat shields on the car. I took a look and noticed that one of the heat shields had dropped from the retaining bolts onto the top of the muffler. 5 mins later I fixed it myself for $0.20 (3 washers) and it's been fine ever since.

So I used the propane torch and it worked well... Too well. The drain piece (that the plug threads into) came off. It's probably good because I was able to clean up the surface.



Can I get a replacement drain (and petcock?) that I could solder on? The propane torch with the solder (and flux) seemed to work really well. So I think a replacement would go on well.

Any tips on soldering a new one on? Should I heat the surface, put some solder on, while hot place the replacement drain on, heat again and solder? Not quite sure of the process. Or should I just put flux on, place the replacement drain on, add flux and solder?

This can be touchy because you can get all the solder joints hot including all the radiator tubes and you don't need a leak there. I would use some heat sink paste to protect parts you don't want to get hot.

You will need a 1/4" or 3/8" close brass bulkhead fitting to sweat onto the radiator bottom tank to install a petcock into.

Something similar to this without using the lock nut or washer:


http://www.amazon.com/Weatherhead-Tubin ... ad+Fitting

Then you can install a regular petcock:



http://www.amazon.com/Primefit-CT1003-4 ... ss+petcock

I showed the 1/4" however you may prefer the 3/8" equivalent.

Dry fit the bulkhead to ensure a good fit.
Clean up the area well.
Apply flux to the tank and bulkhead.
Insert the bulkhead into place and with the flame from your torch pointed away from the tank seam, fan switch and radiator tubes heat the bulkhead and surrounding area until its hot enough to flow solder feeding it all around the bulkhead. If heated correctly the solder should suck right in. Be careful to not overheat and burn the fitting or the radiator or it will get brittle and more prone to corroding and cracking.

Install the new petcock when everything has cooled using pipe dope or Teflon pipe joint tape to ensure a good seal.

Whatever you choose be careful that you do not have the torch so high that you loosen the lower tubes or lower tank seams or you will have no end of problems. Remember that the petcock should not be installed in the bulkhead until after its sweated in and cooled.

Similar to these should be available at a good auto-parts or hardware/plumbing supply store.

Great info. Thanks.

The rad is out of the car and drained which should make things easier. If I borrow the rad pressure tester kit is there anyway to test the rad out of the car? I guess I'd have to figure out how to plug up the inlet and outlet of the rad somehow. I'd hate to try to fix it and have to reinstall to test. There is some mention of people using a cut bicycle inner tube with a clamp holding it in place over the inlet and outlet. Then pump up to 13 PSI.

A set of plumbers test plugs would do it:
http://www.amazon.com/LASCO-13-1820-Eco ... GMYRZ4JH11

Just resist the urge to over-inflate them.

Use wet towels around the other joints to keep them cool. Small flame

Yep. Saw the trick with the wet towels. And small flame sounds good. What about a drain cock?



I would get one that would fit tight in the hole and then solder it in place. Our local Cdn Tire sells these and seems straightforward. I went to a number of places yesterday (auto parts store, plumbing store and fastenal) and they had no idea what I was talking about when I mentioned the bulkhead brass fitting.

You generally do not sweat in a drain cock.

You sweat in a bulkhead or a bushing and then thread the drain cock into place.

The bulkhead is preferable since it has a flange to sweat to the face of the radiator tank instead of trying to get it to hold just on the edge of the thin sheet brass that the radiator bottom is made of.

DieselSpider wrote:You generally do not sweat in a drain cock.

You sweat in a bulkhead or a bushing and then thread the drain cock into place.

The bulkhead is preferable since it has a flange to sweat to the face of the radiator tank instead of trying to get it to hold just on the edge of the thin sheet brass that the radiator bottom is made of.

Actually I bought the drain cock and threaded it in but also soldered it into place for good measure. Actually the solder job looks really good. I was able to apply the flux and the solder just pulled right in. BUT I still think there is a leak somewhere else. I filled it up last night but noticed a few drips of water on the bottom corner. Looks like it might have a small leak near the side/bottom where the side bracket attaches to the bottom bracket/bulkhead.

I borrowed a rad pressure tester kit but none of the adapters fit correctly into the rad cap opening (!). I can't compress the test cap under the lip of the rad cap opening to turn it into place. They also loan a set of what they call GM/Ford adapters. Not sure if they might fit.

Argh! I should just buy another rad but the shipping cost is kind of crazy.

I suppose I did not state that clearly - You are not supposed to sweat a drain cock since the heat can distort it and loosen the crossbar leading to leaks and the crossbar failing. The only time you sweat a valve directly is if you can disassemble it and heat only the body of the valve and not the stem. Yes this is more critical in valves with a packing on the stem and a rubber or plastic seal on the seat however it is best practice.

Yep. The new drain cock actually doesn't leak at all. But once I pressure tester I had other leaks. Cutting my losses and getting a new rad!