How Do I Fix a Leaking Freeze Plug?

As vehicles have gotten more and more advanced both consumers and environmentalists have required them to get increasingly more efficient, produce more power, use less gas and produce less harmful emissions products.

Leaky Freeze PlugOne major advancement in the efficiency of the internal combustion engine was the water cooling system.  The efficiency of an internal combustion engine is proportional to the compression ratio, meaning the higher the compression ratio the more efficient the motor will be.  The difficulty is that a higher compression ratio will produce higher combustion and exhaust temperatures.  These higher temperatures if not properly controlled can cause damage to the engine components like the piston rings and valves.  Adding a water cooling system allows for the excess heat to be removed and the engine to safely operate with a higher compression ratio.  Air cooled engines were used to some extent in older vehicles like the Volkswagen Beetle and the Porsche 911, but today are mainly used in motorcycles to reduce weight and complexity.

In modern cars, cooling systems have gotten even more complicated to include your radiator, the engine block, a heater core and the hoses and lines connecting them all together.  Many cars also have other cooling devices associated with the cooling system like a transmission cooler or oil cooler.

All of these cooling components help the engine in your car run smoothly and more efficiently.  If an engine is designed to be water-cooled it is designed to have higher operating temperatures, higher compression ratios and produce much more heat.  This reality makes it essential to any water cooled motor to ensure the system is operating properly or it could easily render the vehicle inoperable.

Why is my freeze plug leaking?

The difficultly with operating a water-cooling system in your vehicle is that most vehicles at some point will be operated in a climate that has temperatures below freezing.  When water freezes and turns from a liquid to a solid it actually expands, or increases in volume.  This increase in volume causes many problems around the world today, like frost heaves in the road and broken water pipes in your house.  The cooling system in your car is susceptible to the same problem if it were to contain pure water.  The best solution to this problem is the add antifreeze to water lower the temperature at which it will freeze.

What happens when the water freezes in your car?

Leaking Freeze PlugWhen water freezes, it can exert well over 10,000 lbs per square inch of pressure on the container it is in.  In the case of the water jacket in your engine block, this is more than enough pressure to cause it to crack destroying your engine.  The engine in your vehicle also has a secondary line of defense against freeze damage, freeze plugs.  Freeze plugs are usually aluminum or brass plugs pressed into holes in the water jacked of your engine block.  In some cases, as the water freezes and expands in your block, the freeze plugs will push out relieving the pressure of the freezing water and partially draining your cooling system.

A leaking freeze plug can be an indication that your cooling system did or came close to freezing.  When a leaking freeze plug is found, the engine should be checked for damage and antifreeze checked for the proper mixture and freezing point.  However, freeze plugs can also start to leak over time simply due to the heating and cooling cycles of driving your car.

How do you remove a freeze plug?

Leaking Freeze Plugs

Replacing a freeze plug can be a frustrating job since it requires the draining and refilling of your cooling system, and the old plug will likely have to be destroyed to be removed.  Instead, add BlueDevil Pour-N-Go to your cooling system.  BlueDevil Pour-N-Go is incredibly simple to use and will permanently seal a leaking freeze plug without having to drain and refill your cooling system or ever crawl under your vehicle.  BlueDevil Pour-N-Go uses a chemical that reacts to the temperature differential at the leak point forming a permanent bond that contains no particulate matter so it is safe for your entire cooling system.

BlueDevil Pour-N-Go Head Gasket Sealer

Pick up BlueDevil Pour-N-Go at your local auto parts stores like O’Reilly Auto Parts, NAPA, Advance Auto Parts, Autozone, CarQuest Auto Parts, Bennett Auto Supply, Pep Boys and Prime Automotive.  You can also purchase it directly from BlueDevil here: Pour N Go Head Gasket Sealer

Pictures courtesy of: and


41 responses to “How Do I Fix a Leaking Freeze Plug?

  1. Aloha
    I have a pin size hole in my core plug (freeze plug) it’s leaking.
    I tried the bars leaking with copper in it and its just leaking out of the
    Core plug. The location of the core plug is located behind the engine and
    Fire wall. How can I take on this project with your product step by step?
    I Am very intrested on trying it but 63.00 in hawaii it’s pretty pricey. I guess
    This would be my last step because i bought it for 500 bucks and not
    worth going through the labor work or paying a mechanic. Please
    Advise. I have pictures of the leaking freeze plug upon request.
    Michael Morgan

    1. Michael,

      Please give our tech line a call for some additional support. Our BlueDevil Head Gasket Sealer (Part #38386) should do the trick for you. It does require a full radiator flush prior to installation. Call 1.888.863.0426 at your convenience and we can assist with any installation questions.


      1. Hello I have a 97 Toyota Corolla which product should I use to plug the leak which has caused to replace the radiator and the alternator belt. Please advise

      2. I have Ford Taurus 2002. I used K seal over a year ago. It worked, but I lost a lot of heat. Recently, the car was blowing heat and smoking. Well it seems that the antifreeze is leaking again from the freeze plug. Will your sealant stop the leak without clogging the heater core? I don’t see a radiator on my car. Is it absolutely necessary to flush the radiator before I use your product? Should I just go back to K seal?

        1. Mitchell-

          Thank you for asking about your Ford Taurus. The BlueDevil Head Gasket Sealer does not contain any solid or particulate matter, so it is a non-clogging product. If your vehicle only has a reservoir/overflow rather than a radiator cap, instead of pouring BlueDevil through the reservoir/overflow, with the car off and engine cold you should disconnect the top radiator hose and add the product there; do not pour it into the reservoir. It may be added into the hose or the opening on the radiator. Once BlueDevil has been added, reconnect the hose and start the idle from that point.
          It would be absolutely necessary to flush your cooling system prior to using BlueDevil, being that a different manufacturer’s chemical was used. We wouldn’t advise mixing the two.

          Thank you!


    2. Hey Dealing with a freeze plug problem would Like To See The pictures you have of a Leaking freeze plug if You still have, I see that you posted this back 2013 … but if You still have, I would appreciate seeing them, so that I can compare to what I See leaking on my own car ……. Thanks for your time

      P.S. Also one question, If a freeze plug is leaking could that cause a car not to start due to all the antifreeze that comes right back out of the car once filled ?

    3. My Toyota tundra leakes water from back of motor some times more than others will this product help in my case ?? Thanks

  2. Im really assured that your product has what it takes to fix my freeze plug problem and im going to go purchase some of your product later this morning. Its ridiculous how some merchants, mechanics rather rip you off, than resolve such car catastrophe.
    Sincerly, Mr. Larry White

    1. Not all of us do, some yes but not all mechanics do. The right way to fix anything that’s broken or worn out is to replace it. I will try this product as well and if it does I’ll swear by it. Good luck with your issue as well.

      1. Can i ask what you think of this product i have a 92 mr2 turbo im pretty sure the freeze plug behind the water pump is leaking or just gone , think this stuff would seal it

  3. I have a 98 Ford ranger and I have a freeze plug leaking rather profusely like in the above picture. I pour water in and it starts flowing out the freezer plug, which is located behind the motor mount. Would the radiator and block sealer stop a leak like this?

    1. Kyle-

      Based on the extremity of your leak, it is larger than what BlueDevil Radiator & Block Sealer is intended to fix. The product would be lost prior to it being able to create a seal due to how quickly the coolant is being lost. Your only solution may be to have the freeze plug replaced.

      Thank you!


  4. my toyota camry 2001model is licking water through the core plug and i dont want to remove my engine. What can i do ????

  5. My 97 Mazda B4000 automatic transmission, 2 wheel drive is leaking trans fluid from what appears to be a small freeze plug on the transmission housing on the rear driver side on the top of the housing. What kind of plug is that? It is right next to the electrical wiring harness, but on the top driver side housing. Please advise?

    1. Patrick,

      Thanks for your question about your 1997 Mazda B4000. Most transmissions don’t come with freeze plugs installed as automatic transmission fluid won’t freeze until temperatures far below what your truck will be operated in so the part you’re looking at could be a sensor or a cover where your transmission could have come with another option. If the plug is threaded or has any way to be removed without destroying it you could try removing it, cleaning it, and reinstalling it with a small amount of gasket making compound since it’s at the top of the housing it’s most likely above the fluid line. Unfortunately, we can’t tell you for sure what the part is since it’s vehicle specific but you may consider taking your truck to a local transmission shop to get their opinion.

      Thanks again for your question!
      -BD Auto Pro

  6. I have inherited a 1962 Ford Ranchero, 6 cylinder 170cu. engine with manual transmission. She sat in a garage for 25-30 years, I’ve recently got her driving. The rear freeze plug over the starter is leaking. Can your products help? Which product?

  7. I have a 95grand marquis and was told that my freeze plug behind my flywheel was leaking and i had to have the engine or transmission taken out to fix this. It is nit leaking really bad, i might have to put water in my car every other day or so. Will this product help me?

    1. I have a 94 integra LS with a B18B1 motor. I’ve gone through a bottle of coolant in under 24 hours because of a leak back by the motor. It really started to drip once I got to my destination and after sitting for roughly 10 minutes it looked like it had just drained. Is this something if I had the pour n go head gasket sealer, that could be fixed or is this a larger issue at hand?

      1. Ian-

        Thank you for asking about your Acura Integra. Based on your description, we would recommend using the BlueDevil Pour-N-Go Head Gasket Sealer for your coolant leak. The product is intended for leaks that are seeping or lightly dripping. As long as the vehicle will maintain idle for the full 50 minutes, and you are not losing more than about a quart of coolant during that 50 minute run, you would be a good candidate for the product.

        Thank you!


  8. It was maybe twelve degrees here in Fayetteville NC today, Jan 5 2018… I warned my 96 Mercury Grand Marquis up, drive off and maybe five seconds later my whole engine bay was full of steam and temp gauge was jumping!!! I instantly packed the car took a look at what was going on and I saw nothing except steam coming from my radiator and around my thermostat housing but no major leaks nor was I loosing coolant…… Any advice would be heaven sent!!

    1. Jamie-

      Thank you for asking about your Mercury Grand Marquis. Please contact out technical support line at 888-863-0426 so that we can get a better understanding of the vehicle’s condition and be able to make any appropriate recommendations.

      Thank you!


  9. Freeze plug seeping on Big Block V8, will the pour-n-go work, bottle says it’s for 4 and 6 cylinder engines.

    1. Jimmy-

      You may still use the Pour-N-Go Head Gasket Sealer for your Big Block V8. You would need two bottles, being that it is a larger engine.

      Thank you!


  10. I have an 87 Chevy suburban an the freeze plug that’s by the transmission is leaking real bad will your product fix the problem if it’s a big leak or hole in the freeze plug

    1. Tabitha-

      Thank you for asking about your Chevy Suburban. Unfortunately, the BlueDevil Head Gasket Sealer isn’t intended for major leaks. It is intended for leaks that are seeping or lightly dripping from the system. If you are losing coolant too quickly, you would probably be losing the product just as quickly, and wouldn’t be able to keep it in the system long enough in order to get the benefit of using the product. A hard part repair may be your best option.

      Thank you!


  11. I have a 91 Honda Accord with what I think maybe a leaking freeze plug. I had water/coolant dripping from my engine can’t tell if the motor is leaking from the top or bottom sense everything is so compact. I only paid $500 for the car an Unfortunately I didn’t know this was a common issue that could cause more damage an I drove the car for 3k miles with the leak an now the coolant/water is drizzling out. Do you think I may have caused a crack somewhere else. An do you think I would have luck with this product? Ty for the help

    1. Josh-

      Thank you for asking about your Honda Accord. Unfortunately, it is not uncommon for the condition of an untreated leak, over time, to become larger. As long as the vehicle can maintain idle for a full 50 minutes, and you are not losing more than about a quart of water/coolant during that 50 minute run, you would be a great candidate for the BlueDevil Head Gasket Sealer. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!


  12. I have a 94 Ford Ranger and I have a freeze plug leaking in back of the motor that would require pulling the transmission I am told. It’s not leaking bad but it’s enough to leave a small spot of water on the driveway at night. As a matter of fact when the engine is hot it doesn’t leak at all. Can this product help?

    1. Anthony-

      Yes, the BlueDevil Head Gasket Sealer would be able to treat the leaking freeze plug on your Ford Ranger. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!


  13. I have a 2005 Chevy truck that has a freeze plug leak on the back of the engine. It is a steady small stream, will your product fix this leak?

    1. Mike-

      Thank you for asking about your Chevy. As long as you are not losing more than about a quart of water/coolant during the 50 minute run, you would be a good candidate for the BlueDevil Head Gasket Sealer.

      Thank you!


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