How to Stop a Freeze Plug Leak


leaking freeze plug, engine blockHaving a freeze plug leak is pretty rare on cars today.  That’s because there is no movement of your freeze plugs and they are a metal seal rather than a rubber gasket or o-ring.  When an engine is built the freeze plugs are hammered into the plug and as they slide in the metal bends conforming to the freeze plug hole creating a really good seal.  Even though they are one of the best seals on your engine, it is possible to have a freeze plug leak.

In this article, we’re going to talk through everything you ever wanted to know about freeze plugs!

How to Stop a Freeze Plug Leak?

Like any leak, you can replace it or use a stop leak.  Due to the location of freeze plugs and the difficulty of installing them replacing them with a new metal freeze plug often isn’t an option.  Some manufacturers make rubber expandable freeze plugs but we don’t recommend using them as they often protrude into the cooling jacket creating a hot spot and usually don’t hold up very long leaving you with a leak again.  If you’re looking for a stop leak, BlueDevil Pour-N-Go Head Gasket Sealer is the right one for the job.  BlueDevil Pour-N-Go head gasket sealer is a nonparticulate sealer that won’t damage or adhere to anything else in your system except the leak point.  It’s permanent and guaranteed.

Why does your engine have freeze plugs?

Freeze plugs are installed to hopefully protect your engine block in case your antifreeze isn’t properly mixed.  If you don’t have adequate freeze protection the freezing water in your cooling jacket can exert over 100,000 PSI on your engine block which is more than enough to crack cast iron or aluminum.  A cracked block makes your engine just about useless as they are extremely difficult to repair.

Can I replace a freeze plug while my engine is in my car?

As we discussed earlier, most likely not.  First of all, even a leaking freeze plug is very difficult to get out of your engine block due to the tight seal.  The freeze plug will probably need to be drilled or cut out which can damage your engine block if you’re not careful.  Once you get the old one out your need to pound the new one in.  It takes a lot of force to press a freeze plug into a block so you need a straight shot, a big hammer, and a lot of patience.  Usually, having a good enough friend that is willing to hold while you hammer is a requirement as well.

Can I drive with a bad freeze plug?

If you have no other option, you may be able to drive with a bad freeze plug.  Freeze plugs rarely fall out or fail completely so they cause slow leaks.  As long as you keep your engine coolant full and your engine never gets hot, you could limp your car along with a leaking freeze plug although we never recommend it.  It’s messy and at any point could leak to your engine overheating.

You can pick up BlueDevil Radiator Pour-N-Go Head Gasket Sealer of your local auto parts stores like:

  • AutoZone
  • Advance Auto Parts
  • CarQuest Auto Parts
  • NAPA Auto Parts
  • O’Reilly Auto Parts
  • Pep Boys
  • Canadian Tire
  • Walmart


14 responses to "How to Stop a Freeze Plug Leak"


  1. Mark McDonald on January 28, 2021 at 4:37 pm

    Thank you I’ll try it

  2. Aobakwe on February 10, 2021 at 2:57 pm

    I will extremely use it due to more info

  3. Joshua on March 9, 2021 at 3:56 pm

    I see here you recommended pour and go head gasket sealer, what is the difference between that and the pour and go head gasket repair? The only sealer I could find listed 4 and 6 cylinders but I managed to get some blue devil pour and go 2x head gasket repair at my local auto parts store. Will this be suitable for an 8 cylinder truck with a leaky freeze plug?

    • BlueDevil Pro on March 9, 2021 at 5:04 pm


      The BlueDevil Head Gasket Repair is 2x the sealing power of the Pour-N-Go Head Gasket Sealer. It is double the strength and still an easy to use, do it yourself product. You would need two bottles of the BlueDevil Head Gasket Repair for your 8-Cylinder engine.

      Thank you!


  4. James on March 13, 2021 at 11:31 am

    I see that two bottles of head gasket repair are required for an 8 cylinder engine. How about a V10?

    • BlueDevil Pro on March 15, 2021 at 9:45 am


      What kind of vehicle is it? Please contact our technical support line at 888-863-0426 so that we can get a little better understanding of the vehicle and be able to make any appropriate recommendations.

      Thank you!


  5. robert Raymond Robinson on August 12, 2021 at 9:46 pm

    Will blue devil work on rubber and metal freeze plugs

    • BlueDevil Pro on August 13, 2021 at 11:15 am


      BlueDevil Head Gasket Sealer would work for metal freeze plugs, not rubber.

      Thank you!


  6. James on November 8, 2021 at 12:21 pm

    Good afternoon, I am thinking about purchasing a 1989 Foard Coachman 450, the seller is telling me the Freeze plugs are bad and that it leaks anti-Freeze. How much BlueDevil Head Gasket Sealer would you recommend or should I simply take it to a mechanic?

    • BlueDevil Pro on November 8, 2021 at 2:36 pm


      Yes, BlueDevil would be able to treat the leaking freeze plugs on your Ford Coachmen 450. The BlueDevil Head Gasket Sealer (32 oz. yellow label) has a cooling system capacity table on the back of the bottle, which would show you how much product to use per the system you are working with. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!


  7. Amjad on November 29, 2021 at 5:24 pm

    Blud devil work on tx4 London taxi

    • BlueDevil Pro on November 30, 2021 at 8:40 am


      Yes, the BlueDevil Head Gasket Sealer is safe and compatible to use on your TX4 London Taxi. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!


  8. Tom Christenbury on December 4, 2021 at 11:45 pm

    2011 Audi Q7 3.0T gas Base (premium) model, has a leaking freeze plug. What leak stop do you recommend?

    • BlueDevil Pro on December 6, 2021 at 8:55 am


      Thank you for asking about your Audi Q7. The BlueDevil Head Gasket Sealer would be the best product to use for your leaking freeze plug. As long as you are not losing water/coolant too quickly, you would be a good candidate for the product. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!


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