Dig up the area where the cracked PVC elbow joint is located, if it is underground. Open the jaws on a pipe cutter, and insert them around one edge of the PVC elbow joint where it connects to another PVC pipe. A very temporary fix would be to seal over the crack via your ideas. But I would replace that section as soon as possible. And I would really be cautious if that pipe carries any amount of pressure.
How To Fix Crack In Concrete
If you have a PVC pipe leak, you will need to repair it as soon as possible in order to avoid water damage in your home. You could call someone to do the work for you; however, it will not be cheap and you could just as easily do the work yourself. This handy how-to guide will show you everything you need to know to repair a PVC pipe leak.
How to Repair Tiny Hair Line Cracks
Step 1 - Turn Off Water
If the leaky PVC pipe is used to provide water in your home, locate the proper isolation valve and turn off the water flow to the pipe. If an isolation valve is not available, turn off the water at the main shutoff valve in front of your home.
Step 2 - Locate the Crack
How To Fix Crack In Pvc Pipe
Carefully inspect the surface of the PVC pipe to see if you can locate the small hairline crack that is causing water to drop or leak from the pipe. After you locate the crack, use a marker pen to circle the crack so that it is easy to find.
Step 3 - Sand the Cracked Area
Take a piece of sandpaper and lightly sand the area where you made your mark. This will remove any dirt or residue that will interfere with the PVC glue that you will use to fill the crack.
Step 4 - Fill Crack with PVC Glue
Open up the can of PVC glue and remove the glue dauber. Then, carefully daub a small amount of glue onto the crack in the PVC pipe. Don't use too much glue, but use enough to fill the crack so that it will no longer leak water. Once the glue dries, the small hairline crack should no longer leak.
How to Replace a Section of Cracked Pipe
Step 1 - Turn Off Water
Turn off the water supply that provides water to the pipe unless it is one that is used to drain water.
Step 2 - Cut Out Cracked Section of Pipe
Take the hack saw and cut out the cracked area of the pipe. If possible, cut a section of PVC pipe that is slightly shorter than the PVC pipe coupler that you will be using to repair the leak.
Step 3 - Sand Ends of Pipe
Take a piece of sandpaper and sand away the rough edges that were created when you used the hack saw to cut the pipe.
Step 4 - Install New PVC Pipe Coupler
Dry fit the PVC pipe coupler on the two ends of the PVC pipe to make sure it fits properly. Then, apply PVC primer to the inside of both female ends of the coupler as well as the edges of the PVC pipe. Then, use the PVC glue in a like manner to coat the inside of the coupler as well as the edges of the pipe. Next, fit the coupler onto both ends of the pipe and push the pipe firmly together until the ends of the pipe seat on the lip edges of the coupler. Once the glue dries, the coupler will replace the section of cracked pipe and the leak should be fixed.