Why Does My Car Keep Getting More Coolant Leaks?

I just had my water pump replaced to fix a coolant leak. I drove the car for a couple of days, and now it’s leaking coolant again. The shop I went to told me that my radiator needs to be replaced now. Isn’t this something they should have noticed when they replaced the water pump?

This is a really good question! There are a few important things to know about coolant leaks:

Fixing a coolant leak is kind of like plugging a dike.                        

Once you fix one leak, another one pops up. Water follows the path of least resistance, so it will leak out of the weakest point in the system. Once you have repaired that weak spot, the water will then escape from the next weakest spot in the system. Here’s an exaggerated example: If your water pump had a hole the size of a quarter, and the radiator had a hole the size of a pin, the water is going to be leaking out of the quarter-size hole rather than the pin-sized hole. Once that quarter-sized hole is repaired, and the cooling system is able to operate at full pressure again, only then would you be able to even notice the pin-sized hole from the radiator.

Sometimes there are multiple weak spots in the cooling system that just don’t start leaking until the larger leaks are repaired.

Coolant acts as a solvent.

Think of coolant like a laundry detergent. It is designed with certain cleaning agaents that allow it to clean debris that builds up in the system. Many cars, especially ones that haven’t had the coolant regularly changed, may see that there has been gunk that has built up in the system that is actually helping plug up some of the areas that may otherwise leak. Once new coolant is added to the system, it can actually loosen some of the debris, causing it to “unplug” the leak.

Coolant leaks can be tricky. Even if the shop had pressure checked the system after they replaced the water pump, it may check fine immediately after the repair, but after the new coolant has circulated through the system, it may take a few days or weeks before a new leak surfaces.

This is one of the reasons why it is so important to have your cooling system serviced on a regular basis. Keeping fresh coolant in your vehicle prevents it from having corrosion that can cause leaks in the first place, while eliminating some of those nasty goobers that clog up your cooling system.

Have a question for Dan? Send it to askdan@gascan.com

Dan Amundsen is a Master ASE Certified Technician, with over 40 years of automotive repair experience. He has been the owner of Juanita Firs 76 since 1978. He runs a true family business with his two children, three nieces, and many just-like-family employees that have been with the company for over 15 years.