How to Stop Leaking Radiator Fluid

If you’re leaking radiator fluid or coolant but you’re not sure how to stop the leak, there are a number of ways to repair leaks in your car’s cooling system. Some are quick fixes that aren’t meant to last long, while others are permanent repairs. This article will list a few accepted methods for stopping a radiator fluid, or coolant leak in your vehicle.

Situation #1

You’re stuck on the side of the road and your radiator hose has a small pin hole that it’s leaking from. You don’t have a new hose with you, coolant or the tools handy to replace the hose. However, you do have some heavy duty tape of some sort, such as duct tape. In an emergency situation, duct tape will work long enough for you to have the proper repair, which is replacing the radiator hose.

Step 1: Wrap That Hose Tightly

Use a rag or a towel to dry and clean the radiator hose. Tightly wrap the affected hose a few times. Make sure you wrap at least 4 inches of the hose to ensure that your repair will last long enough to get it done properly.

Situation #2

You’ve noticed a very small leak in 1 of the cooling tubes on the radiator. There are 2 ways to fix this, the quick fix way, after which the radiator will need to be taken to a specialty shop and fixed properly and a longer term fix. Both of these fixes should be considered temporary, although the second option will last quite awhile.

Fix #1: Backyard Mechanic Style

Talk to any mechanic who’s been around for more than 5 or 10 years and you‘ll be told that the best way to seal pinhole leaks in the radiator is with regular, everyday coarse ground table pepper. With the engine running and at operating temperature, carefully remove the radiator cap. Pour approximately 1 to 2 teaspoons of coarse ground pepper into the radiator opening and replace the cap. Run the engine for approximately 20 minutes and fill to proper level. The grains of the pepper will migrate to the pinhole leak and plug it. The problem with fixes like this is that if you use too much pepper, it will clog the cooling tubes, rendering your radiator ineffective. For this reason it’s imperative that you take it to a specialty shop and have the radiator thoroughly cleaned out and soldered.

Fix #2: The DIY Mechanic

There are a number of products available that seal small holes in radiators and the rest of the cooling system. The 2 most popular are Alum-A-Seal and Bar’s Leak (both trademarked names). Follow the label instructions when using either of these products. Basic repair operation goes as follows: Open the container and put the product into the radiator fluid and replace the radiator cap. Then run the engine for 15 to 20 minutes and recheck coolant level.

Fix #3: The Professional Way

The overall best way to fix a leak in your radiator is to take it to a specialty shop and have them clean it out completely and then solder the leak closed.