This can be fixed-today. A...
This can be fixed-today. A bolt went through here leaving a trail of destruction. Localized damage such as this is easily repaired.
The first thing I can say about fixing a radiator is--don't. The cost of a racing radiator has come down over the last few years. For the most part, an aluminum racing radiator may now be less expensive than a brass OE type.
When a radiator core needs repairing, that usually means some of the tubes must be closed off. This will reduce the cooling capacity because the affected water passage tubes will no longer flow water. The amount of cooling reduction will depend on how many tubes are damaged.
For this article, a Howe Racing Radiator is being prepared. It suffered a substantial hit in a side tank and never leaked. However, when a bolt went through the tubes
The positive side of repairing a damaged radiator is that you can return it to action in about eight hours. Also, the repaired radiator can be kept in the hauler for a spare. When a radiator is damaged early in the night, you will then have something to run in the feature.
Using needle-nosed pliers,...
Using needle-nosed pliers, remove as much as possible of the damaged fin area near the break in the water tubes. Pinch off the tubes if possible. Don't compress the fins more than necessary to remove the damage.
The following fix is directed toward aluminum radiators, although I have no doubt it will work on brass radiators, as well. Brass radiators should be cleaned with lacquer thinner to remove the black paint in the affected area.
The first step is cleaning. Grease, oil, or antifreeze must be cleaned from the damaged area. I use two different cleaners. The first is denatured alcohol. (This is not rubbing alcohol, which contains various amounts of water.) After the coolant is drained, pour some of the alcohol in the radiator. Turn the radiator so the alcohol runs out the damaged area. This cleans the radiator from the inside.
Next, with the radiator sitting on a bucket, pour some of the alcohol over the damaged area. When this has evaporated, spray the area with a nonflammable brand of brake cleaner such as Justice Brothers. The brake cleaner leaves no residue and removes any oil that might still be present. This cleanliness is important when using adhesives.
The next step is the tape. Yep, masking tape. I prefer the blue tape because it is easier to remove. Select the side of the radiator with the least amount of damage. Lay the tape over the damage. You should tape a much larger area than what might seem necessary. Rub the tape to make it stick, but don't bend the fins.
Cleaning the damaged area...
Cleaning the damaged area is vitally important but easy to do. Pour one-half cup of denatured alcohol in the radiator. Turn the radiator so the alcohol will pour out the damaged area. This cleans the radiator from the inside. Then pour alcohol on the outside of the damaged area. Finally, spray the area with nonflammable brake cleaner to remove any oil that might be left. Blow-dry the area.
On the other side, using needle-nosed pliers, pull the damaged fins away from the damaged tubes. If you can reach the tubes, crimp the ends with the pliers. If you can't reach all the damage, that's OK as long as you did a good job of cleaning.
Lay the taped side of the radiator down flat, preferably on some blocks so you can see under it. Under any conditions, the radiator should be level.
Now you are ready to start making the patch. The active ingredient is J-B Weld, a product of the J-B Weld Company, which makes two products you may be familiar with: J-B Weld and J-B Kwik. The J-B Kwik, which sets up in four or five minutes, is as strong as J-B Weld but won't run in and fill the gaps as well because of the short setup time. For the same reason, it doesn't have as much adhesion.
I have used J-B Weld for as long as it has been on the market. There are a number of other two-part epoxy products available. I've never found any to be, on all counts, the equal of J-B Weld. I have repaired engine blocks, cylinder heads, and hydraulic rams in garbage trucks with the stuff. If the metal is clean, J-B Weld works.