How to Repair a Leaking Car Radiator

The radiator is the start of your car’s cooling system. Coolant from the engine travels through tubes in the radiator. These tubes are surrounded by fins designed to direct airflow. The air cools the coolant, which then travels back to the engine, allowing it to run at the proper temperature.

Radiators can develop leaks in several places. These include the hoses, seams, tubes and cores. Without a properly functioning radiator, your engine will quickly overheat. This is something you want to avoid at all costs since overheating can cause extensive engine damage.

The best way to fix a leaking radiator is to replace it. However, there are ways to temporarily fix a leaking radiator until you can get it into a shop for repair. These strategies come in handy during emergency situations.

Part 1 of 2: Locate the leak

Materials Needed

In order to safely inspect and seal the radiator, you need a couple of basic tools:

front view of leaking car radiator

Step 1: Locate the leak. Before you do anything else, make an attempt to locate the leak.

There are many places coolant leaks from, so you want to make sure it is actually coming from the radiator.

radiator pressure tester

Step 2: Use a pressure tester. If you can’t easily spot the leak, you can use a pressure tester on the system.

This tool pressurises the system without the engine running, making leaks easy to spot. To use the pressure tester, attach it to the radiator or reservoir using the appropriate adapter, pumping it up to 15 PSI, which should then reveal the leak.

  • Warning: Do not exceed this pressure or damage to the cooling system may occur. Pressure testers can be rented from most auto parts stores.

Part 2 of 2: Fix the leak

Step 1: Fix the leak. Once you have found the leak, you should determine the best way to fix it.

There are a several ways to temporarily do this. These include adding a bottle of cooling system sealer, an egg, black pepper or epoxy glue. In some cases, the radiator can also be soldered or welded.

The table below will give you a better sense of how each of these methods works:

leak fix methods
  • Tip: If you are able to welder or solder, replacing the whole radiator may be the way to go

mechanic installing a new radiator

Step 2: Get your vehicle to a trained professional. Sometimes the best course of action is to have a professional examine it.

Many repairs to a leaking radiator are temporary fixes. The only permanent and safe repair is radiator replacement by a trained professional. If you added some form of stop leak to your cooling system, don’t forget to tell your technician. One of YourMechanic’s certified professionals will gladly come to your home or work to perform an installation of a new radiator.


Next Step

Schedule Car Radiator Replacement

The most popular service booked by readers of this article is Car Radiator Replacement. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Car Radiator Replacement reviews

Excellent Rating

(2,220)

Rating Summary
2,080
71
8
17
44
2,080
71
8
17
44

William

35 years of experience
731 reviews
William
35 years of experience
Dodge Journey L4-2.4L - Radiator - Phoenix, Arizona
I was glad that the mechanic i was able to secure for my appointment was Will. He has helped us out with other repairs before and he's been great. He showed up early, was finished in a timely manner and helped me understand how to avoid issues in the future and made some great recommendations.
Ford Ranger - Radiator - Peoria, Arizona
William is by far the best mechanic at your company. He is professional, competent, and thorough. He not only performed all the repairs I requested which were many, but also found and corrected repairs by another company which would have been costly to my vehicle down the road. I will request him for any future service or repairs to my truck. I trust his diagnoses completely.

James

31 years of experience
1039 reviews
James
31 years of experience
Land Rover Discovery V8-4.6L - Radiator - Apopka, Florida
Excellent service! Arrived on time, very courteous and professional. Did a great job on the work that was needed. Offered service suggestions on other issues I was having with my car also. I will definitely be booking again.
Nissan Altima - Radiator - Altamonte Springs, Florida
James was very thorough and helpful and put me at ease with the process. I really liked how efficient he worked and on time.

Pardeep

22 years of experience
1277 reviews
Pardeep
22 years of experience
Toyota Tacoma V6-3.4L - Radiator - San Jose, California
Very personable gentleman. does the work quickly is familiar with a vehicle, I am very satisfied with his work and will use his services again.
Lexus IS300 - Car Radiator Replacement - Santa Clara, California
Very friendly and knowledgeable. Great communication, on time and fast service. I would definitely recommend Pradeep!

Anthony

8 years of experience
195 reviews
Anthony
8 years of experience
Toyota Highlander V6-3.5L - Radiator - Orangevale, California
Anthony was great. Very friendly and professional. Did the work in less time than I thought and saved me some money.

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

How Long Does a Vacuum Hose(s) Last?
Most Most car owners fail to realize just how important air flow is to the running of their vehicle. Nearly every system on your car requires air flow in order to function properly. The negative air flow, or vacuum, that...
How to Change a Radiator Valve
A radiator valve allows coolant into the radiator in order to cool off the engine once the coolant has reached a certain temperature.
How to Replace a Radiator Drain Cock
The radiator drain plug goes bad when the oil pressure is lower than normal, there is leaking coolant, or the Check Engine Light is on.

Related questions

Engine over heats no heat
If you do not have any circulation through the radiator then you may have a clogged radiator cores inside. If you used stop leak in the engine then you may have plugged up the radiator and heater core. You should...
A/C not cooling in idle, only on high rpms
Hi there. This typically means that the fan itself has failed or there is a problem with the circuit. I usually start by checking for voltage supplied to the fan when the A/C is turned on. If there is voltage...
2007 Dodge Grand Caravan hard detonation problems
Take a compression tester and check the compression of each cylinder. This will determine how much pressure will hold in the cylinders. If the pressure is 120 or higher, then the cylinders are okay. If the pressure is lower than...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com