How Can I Fix a Leaking Heater Core?

heater coreHaving a leaking heater core can be one of the most frustrating leaks you can have in your vehicle.  Almost any leak in your car is an external leak, meaning the leaking fluid will just leak out onto the ground.  Sure, that isn’t the best for the environment and it can make a mess in your driveway or the parking lot at work, but at the end of the day as long as you keep your fluids topped off, you can keep driving your vehicle relatively comfortably

A leaking heater core usually will cause a much more annoying leak.  On most new vehicles, the heater core is inside the cabin of the vehicle.  Even if you have an older vehicle with the heater core outside the cabin, leaking fluid can still find its way into the cabin through the ventilation ducts.

Having coolant leaking into the cabin of your vehicle can cause all sorts of problems.  First, when your car isn’t warmed up yet, the coolant will make a mess on your floorboards and possible start the process of corrosion.  As the coolant leaks onto your floor it will soak into your carpet and the padding.  As this moisture stays trapped in your carpet it can start to corrode the floor pan in your car.  Since this is all happening under the carpet, it can quickly get out of control without you ever knowing.  In the worst case, this corrosion can compromise the integrity of the floor of your vehicle making it unsafe.

Another problem with coolant leaking into the cabin of your vehicle is that once it is warmed up, that coolant will be almost 200 degrees!  This hot coolant will quickly turn to steam in your car and will definitely cause an unpleasant odor.  The steam can also quickly spread through your ventilation system making it very difficult to remove the odor.  Depending how big the leak is, the steam can cause fogging problems on your windows and leave you with no way to clear the condensation since it is your ventilation system that is spreading the problem.  Lastly, antifreeze is a poisonous substance so breathing in its vapors can even be harmful to you and your passengers.

If you have a leaking heater core, then you may have experienced some of these symptoms and have realized how frustrating it can be.  It isn’t unusual for heat cores to develop leaks because they are often made from relatively thin metal to help aid in the heat transfer from the hot coolant inside to the air being blown over it by your vehicle’s HVAC system.  This thin metal can develop cracks over time and the joints in your heater core can start to come loose due to vibrations in your vehicle and bumps in the road.

Replacing a leaking heater core can be an extremely annoying project due to its location in your vehicle.  The heater core needs to be right next to the fan that pushes the air through your ventilation system.  That fan needs to be near the firewall of your car so it can have the ability to both pull air in from outside the vehicle, or recirculate the air in the cabin depending on the settings of the system.  If you have air condition in your car, then the AC evaporator will be right next to the heater core which is also a delicate piece of equipment that is difficult to move.

Fixing a leaking heater core will always be much easier than replacing one.  Since it is only a small leak in the heater core, we recommend simply sealing that leak and leaving your heat core in place.  You can do this by simply by adding BlueDevil Pour-N-Go to your vehicle’s radiator when your vehicle is cold.  When BlueDevil Pour-N-Go reaches the leak point, the temperature differential will cause a chemical weld to form sealing your leak without affecting any other part of your cooling system.

BlueDevil Pour-N-Go Head Gasket Sealer

To learn more about BlueDevil Pour-N-Go, visit our website here: Pour N Go Head Gasket Sealer

You can purchase BlueDevil Pour-N-Go from any of our partnering local auto parts stores like:

  • AutoZone
  • Advance Auto Parts
  • Bennett Auto Supply
  • CarQuest Auto parts
  • NAPA Auto Parts
  • O’Reilly Auto Parts
  • Pep Boys
  • Fast Track
  • Bumper to Bumper Auto Parts Specialists
  • S&E Quick Lube Distributer
  • DYK Automotive

 

Pictures provided by:

heater_core.jpg – By JAK SIE MASZ – Licesned By Creative Commons Via Flickr – Original Link

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77 responses to “How Can I Fix a Leaking Heater Core?

  1. I have this problem. I easily found this sight with a search engine and was very impressed. The article is informative and not imposing. Kudos to whoever is in charge of your marketing.
    Thanks,
    Joni

    1. Jenifer-

      Thank you for your question. The direction about putting the heater on to the max is to draw heat from the engine to keep it from overheating during that 50 minute idle. As long as the vehicle isn’t going to overheat during that 50 minutes, the product should be able to help seal your leak.

      Thank you!

      -BDP

  2. I have 2004 Saturn Vue that has a very small leak in the heater core (i believe). No radiator cap and the engine is a Honda V6. I don’t especially want to disconnect the radiator hose to add it and would like to use the coolant reservoir.
    Is this something I can do for this minimal problem?

    1. Jim-
      Due to your vehicle only having a reservoir/overflow rather than a radiator cap, we would have recommended that instead of pouring BlueDevil through the reservoir/overflow, with the car off and engine cold you would disconnect the top radiator hose and add the product there. Once it had been added reconnect the hose and start the idle from that point.

      Thanks for your question!

      -BDP

        1. Troy-

          Yes, if your vehicle only having a reservoir/overflow rather than a radiator cap, we recommend that instead of pouring BlueDevil through the reservoir/overflow, with the car off and engine cold you would disconnect the top radiator hose and add the product there. Once it had been added reconnect the hose and start the idle from that point.

          Thanks for your question!

          -BDP

  3. I have a 2000 dodge ram 2500 with what I believe is a heater core leak. I get no heat when driving and when I turn the truck off, smoke starts coming out of the front. Do you think BlueDevil Pour-N-Go would help or do you think I’ll have to spend $500-$700 replacing it. Thanks!

    1. Sean-

      Thank you for asking about your Dodge Ram. Based on your description, we would recommend using the BlueDevil Head Gasket Sealer (32 oz yellow label). The BlueDevil Pour-N-Go Head Gasket Sealer is intended for use in 4 or 6 cylinder engines. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!

      -BDP

  4. My wife’s 2002 Chevy Blazer was stolen and the next day My wife and daughter tracked down the thief in the blazer and pushed him in a snow bank where it sat for several hours running and in reverse before the cops came and released it to them. The temp in the truck was around 200. The next day windows fogged up and fluids leaked onto the floor board and the heat stopped. Is this the heater core or some other problem. The blower works great, the guages show temps rising to 200 plus but no heat comes out and the windows fogged up.

  5. Poured in Blue Devil pour and go car has a funny smell I can not get rid of after putting this stuff in steam clean the whole car still the same work as a professional cleaner in the past so I know it’s so I know it’s a not about cleanliness

    1. Natale-

      We have not had an issue with the car smelling funny after use of the BlueDevil Pour-N-Go Head Gasket Sealer. Please contact our technical support line at 888-863-0426 so that we can get a better understanding of the vehicle’s symptoms and be able to make any appropriate recommendations.

      Thank you!

      -BDP

    1. Nita-

      Thank you for asking about your Chrysler Pacifica. Based on your description, we recommend using the BlueDevil Head Gasket Sealer, found here: http://store.gobdp.com/head-gasket-sealer-38386/. As long as the vehicle will maintain an idle for 50 minutes, without overheating or stalling out, and you are not losing more than about a quart of water/coolant during that 50 minutes, you would be a good candidate for the product.

      Thank you!

      -BDP

  6. I have a 2002 mercury Sable ..an on my passenger side floor I have a leak probably from heater core but it’s going into my carpet on that side …an my air conditioning is blowing but hot air an no freon is in my air conditioning it leak out all of it ..my question is …can my heater core has something to do with my air conditioning freon leaking out all the way ? Plz help me out ..I need know what to do ..I don’t have much money ..

    1. David,

      Thanks for your question about your Mercury Sable. We can’t think of any way your leaking heater core could be related to your AC leak, it is probably just a coincidence. Our recommendation would be the fix the leak in your heater core quickly to keep your engine from over heating and causing more damage. You can use BlueDevil Pour-N-Go (available here: http://store.gobdp.com/pour-n-go-head-gasket-sealer-00209/) to seal that leak to keep your engine safe. When you have a chance later, you can use RedAngel AC Stop Leak (available here: http://store.gobdp.com/a-c-stop-leak-aerosol-00222/) to seal the leak in your air conditioning, then refill it to get that back to normal.

      Thanks again for your question!
      -BD Auto Pro

      1. I have a question I have a 2000 mits eclipse with a blown head gasket n fixing to use blue devil but my heat doesn’t work so will that be a problem and if it starts to run hot during this process what do I need to do.. Thanks ..

        1. Amanda-

          Thank you for asking about your Mitsubishi Eclipse. The direction of turning the heater on with the blower to the max, while performing the BlueDevil Head Gasket Sealer procedure, is to draw heat from the engine to keep it from overheating during the 50 minute idle. Unfortunately, if the vehicle is unable to idle for the full 50 minutes without overheating, it may just be that the leak you have or symptoms you are having are just a little to extreme for the product. Feel free to contact our technical support line at 888-863-0426 with any other questions.

          Thank you!

          -BDP

    1. James-

      Yes, the product is safe to use with turbo charged engines. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!

      -BDP

    1. Carlos-

      Thank you for asking about your Ford Expedition. Have you noticed a loss of water/coolant? Please contact our technical support line at 888-863-0426 so that we can get a better understanding of the vehicle’s symptoms and be able to make any appropriate recommendations.

      Thank you!

      -BDP

    2. Carlos: I also have a 2000 Ford Expedition with the same problem. Email me if you can and let me know if you were able to get yours fixed. Thanks

      G

  7. There’s a small leak where my heater hose is clamped and connected to my heater core, will this do an adequate job in stopping the leak?

    Vehicle is a 1999 VW Passat 2.8l v6

    1. Pat-

      Unfortunately, BlueDevil Pour N Go Head Gasket Sealer is not intended for that type of leak. If it were the physical heater core leaking then yes, we would recommend BlueDevil. However, due to it being the clamp connection and/or the hose, we recommend having the clamp & hose replaced. This should stop the leak and should be fairly easy to access and replace.

      Thank you!

      -BDP

  8. I have a 1985 camaro and it slowly loses coolant with no apparent sign of leakage on the ground or floor board. I replaced the intake gasket and still, I slowly lose coolant and the car heats up 200°+. The heat works fine, no odor or condensation on windshield. Head gasket?

    1. Does the heater core sealant work for the radiator also? It seems to run fine in cooler weather but when it’s hot out, that’s when I start having problems. Thanks for any info.

    2. A.J.-

      The symptoms you have described are common when a vehicle has a blown head gasket. We recommend using our BlueDevil Head Gasket Sealer (http://store.gobdp.com/head-gasket-sealer-38386/) to stop any coolant loss. The reason you may not be physically seeing some of the tell-tale signs of a blown head gasket is because you are catching it early on.

      Feel free to contact our tech support team at 888-863-0426 with any questions regarding the product and/or your vehicle.

      Thank you!

      -BDP

    1. Mary-

      Please contact our technical support team at 888-863-0426 so that we can get a better understanding of the situation and be able to make any appropriate recommendations.

      Thank you!

      -BDP

    1. Danny-

      Once the product seals, it is a permanent seal. As long as you are not losing water/coolant too quickly, you should be able to see some good results. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!

      -BDP

  9. My son has a 2002 Ford Crown Victoria. We had no issues with defrost or air until a few days ago when the dreaded “green fog” came out of the vents. We suspect the heater core is either leaking or gone bad. Would your product work for us? It would be at least 1200 to replace due to the need to pull out the dash so we’d like to avoid that expense.

    1. Kelley-

      Thank you for asking about your son’s Ford Crown Victoria. The BlueDevil Head Gasket Sealer would be able to seal a heater core leak. As long as you are not losing water/coolant too quickly and the vehicle can maintain idle for 50 minutes, then you should be able to see some good results. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!

      -BDP

  10. I have a Ford 150 and I believe the coolant is leaking because it appears on my passenger side floor. Which product would you reccomend?

    1. Liz-

      Thank you for asking about your Ford F150. Based on your description, we recommend using the BlueDevil Head Gasket Sealer, found here: http://store.gobdp.com/head-gasket-sealer-38386/ . As long as you are not losing water/coolant too quickly and the vehicle can maintain idle for a full 50 minutes, you would be a good candidate for the product. Feel free to contact our technical support team at 888-863-0426 with any other questions.

      Thank you!

      -BDP

  11. Hi
    I have a 2005 Chyrsler Sebring. I noticed a red oily substance on my rear drivers side floorboard. I’m thinking its the heater core causing it. Which product would be best to use??

  12. When I turn on the heat I get the smell of coolant. Obvious I have a leak. If I use this product and if it seals the heater core will I still smell the coolant after the leak is fixed? Or will I have to spray something inside the HVAC to get rid of the smell?

    1. Fernando-

      We would like to speak with you in regards to whether or not you have actually noticed any loss of coolant. Please contact us at 888-863-0426 so that we can assist you in using BlueDevil Head Gasket Sealer. We are available Monday – Friday, 8:00 AM – 5:00 PM EST.

      Thank you!

      -BDP

  13. Hi, I have a 2011 Cadillac and less than 2 months ago the heater core blew, fun fun! Well I just did it again! I’m 200 miles from home and the repair shop. I want to take it back to them, as it was over 1200$ to fix. I feel they should repair it! What can I do to safely drive it until I can get it home. I’m currently soaking up antifreeze with towels out of the floorboard.

    1. T Jackson,

      Thanks for your question about your Cadillac. IF you have a leaking heater core and need to just get your car home, you can locate the feed and return heater lines in your engine bay. They should run into the firewall near each other and one should connect to the engine near the water pump. If you remove the hoses from the heater core and use a connector rated for the temperature and pressure of your cooling system you can temporarily bypass your heater core to get your car back home. Most auto parts stores should sell the correct size connector and clamps you’ll need to accomplish this.

      Thanks again for your question!
      -BD Auto Pro

  14. My F150, 2001has vapor coming into the passenger compartment. It overheats in stop and go traffic. I’ve had to turn on the heat to get the temp gauge away from the red zone. If I leave the air/panel off, it does not overheat. Returning to the time before AC isn’t something I want to do. There isn’t any apparent fluid loss. Will your product help prevent an expensive repair? The first mechanic I went to fix the problem said it sounded like a ‘flow problem’ and replaced the water pump to cure the overheating. That was not a cure. The vapor in the cab has started since then.

    1. Susan,

      Thanks for your question about your F150. Based on the overheating and the vapor in your cabin it sounds like you’ve got a leak in your heater core. It is possible that you’ve got a blocked heater core which could cause the overheated problem you’re having in which case you can try flushing your cooling system with BlueDevil Radiator Flush (available here: http://store.gobdp.com/radiator-flush-00204/).

      Thanks again for your question!
      -BD Auto Pro

  15. I have a 2000 jeep grand cherokee. I have noticed a puddle of water in my passanger side floorboard. I was told it was my heater core. Would the bluedevil fix my problem?

    1. Jinger-

      Thank you for asking about your Jeep Grand Cherokee. The BlueDevil Head Gasket Sealer would seal a leaking heater core. 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!

      -BDP

  16. hi! I have a polo 1.4 tdi 2004 model and I experienced water leaking inside the passenger side and my mechanic opted to disconnect the heater pipes and plug them so there would be no circulation of water to the heater,can this product fix my problem and is it available in SA

    1. DMK-

      Yes, you can bypass the heater core to prevent the leaking you have seen recently. However, if you do so you will no longer be able to successfully use your heater.

      Another option would be to run BlueDevil Head Gasket Sealer (http://store.gobdp.com/head-gasket-sealer-38386/) through your cooling system to seal the leak and stop any coolant loss. The product is available locally through AutoZone, Advance Auto Parts, O’Reilly Auto Parts, and other auto parts retailers near you.

      Thank you!

      -BDP

  17. I have a 2002 Toyota Camry 4 cyl. 326,000 miles.
    I’m getting a fruity smell while the vehicle is running after a little while (15+ mins.). Checked hoses, no leaks. Checked ground,not wet nor no collection of fluid on/in crossmembers. I do have AC and heat, no fogging interior.
    Could this be possibly the start of a head gasket leak? If so what product to use.

    1. Jorge-

      Thank you for asking about your Toyota Camry. Based on your description, it is a little difficult to pinpoint what the issue is. Please contact our 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!

      -BDP

  18. Hi i have a 1993 Jeep cherokee sport with a 4.0 straight 6. There is sweet sticky stuff on the passenger floor, i cleaned the floor and it came right back. It doesnt seem to really be using antifreeze, only a hair here and there. The engine doesnt overheat and the windows dont fog. Is this the heater core? And if so will the blue devil pour-n-go work?

    1. Daniel-

      Thank you for asking about your Jeep Cherokee Sport. Based on your description, it is very possible you are dealing with a heater core leak. The BlueDevil Pour-N-Go Head Gasket Sealer would be able to seal a heater core leak. It doesn’t sound like you are losing antifreeze too quickly, so the product should be able to help seal your leak. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!

      -BDP

  19. I have a 2008 Ford Explorer and it’s dripping coolant from right up by the firewall. I’m almost 100% sure is my heater core. Which product should I use? The poor n go head gasket sealer or the poor N go radiator and block sealer. Why one produced over the other? And what is the best way to use it?
    Thank you so much for your time and help!

    1. Jessie-

      Thank you for asking about your Ford Explorer. Based on your description, we recommend using the BlueDevil Pour-N-Go Head Gasket Sealer, as the Radiator & Block Sealer is specifically formulated for the radiator and/or the block. The BlueDevil Head Gasket Sealer would seal a leaking heater core. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!

      -BDP

  20. I have a very small leak in my heater core and I’m interested in trying a leak sealing product, but I want to keep my car for a while and I’m worried about short term and long term side effects. After the 50 minute idle is over and the car cools down, won’t the temperature differential of the engine cooling down cause the remaining leak sealing product still inside the engine to chemical weld on the inside of the engine and components (water pump, etc)? I read a coolant flush before the treatment is recommended. Is a coolant flush also recommended afterwards to remove the remaining leak sealing product?

    1. Ed-

      BlueDevil Head Gasket Sealer only reacts during 1 heat cycle. It will not coat the entire cooling system; the chemical weld that is created will only be formed at the leak point. You will not need to flush your cooling system after applying the product. You may simply drain the system and refill with your factory recommended antifreeze.

      Thank you!

      -BDP

  21. I have 2002 grand Cherokee Wj and I just changed the heating core because I was having a leak issue in the floor board. It’s still leaking in the floor board after I changed it and leaking outside the jeep. Would this stuff be able to fix my problem? I also believe it’s coming from the hoses under the hood connects to the heater core

    1. Justin-

      Thank you for asking about your Grand Cherokee. Based on your description, it sounds like you may have some loose hose connections. We would not recommend using the product in this case, as the product should not be used for leaking hoses or faulty hose connections. Inspecting and replacing any hoses necessary would be your best option.

      Thank you!

      -BDP

  22. I have 97 Buick Century I’m not sure if I have a broken temorstat or a leak in the heating core or both. I have a foggie windshield there is something on my passager side floor but there is still plenty of coolant in my reserve and my radiator plus the leak only happens when the engine is cold

    1. Willie-

      Thank you for asking about your Buick Century. Based on your description, it seems more likely that you are experiencing a heater core leak rather than a thermostat issue. We recommend using the BlueDevil Head Gasket Sealer to seal your heater core leak http://store.gobdp.com/head-gasket-sealer-38386/. 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 minutes, you would be a great candidate for the product.

      Thank you!

      -BDP

  23. I have a 1996 ranger and the heater core has a leak. So I’ve by passed, but if I can seal the leak I would like to do that. Everything is already flushed out. So how much of the blue devil pour and go would I use and how do I mix it? Does it go in before the antifreeze? And do I do it with the car off and then once it’s filled up start it and let it idle for 50 min correct?

    1. Forrest-

      You will add your antifreeze first just leaving enough room for 16 ounces of BlueDevil Pour N Go Head Gasket Sealer. Once the antifreeze has been added you will start the engine and slowly add BlueDevil through the radiator cap. Once BlueDevil has been added you should tighten the radiator cap and allow the engine to idle for 50 minutes.

      Feel free to contact us at 888-863-0426 with any further questions.

      Thank you!

      -BDP

    2. Forrest-

      Thank you for asking about your Ford Ranger. You would need 16 oz. of the BlueDevil Head Gasket Sealer to properly treat your vehicle. The product is formulated to work with the antifreeze already in your system, so your only real direction is to make sure you have enough room to add the product. When the engine is cold, you would remove the radiator cap and start the engine up. Slowly pour the product in through the radiator cap, put the cap back on, and allow the vehicle to idle for 50 minutes. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!

      -BDP

  24. I have a 2002 Honda Civic and the heater no longer produces heat, it keeps leaking antifreeze, the oil temp gauge has started to go up at higher speeds, and the cabin sometimes smells like antifreeze. I think I have a heater core leak, does this sound accurate? Are there any side effects of adding the Blue Devil product I should be aware of? Things to look for? Is there a point at which adding the product is not likely to change how failed the heater core is?

    1. Garrison-

      Thank you for asking about your Honda Civic. Based on your description, we recommend using the BlueDevil Head Gasket Sealer http://store.gobdp.com/head-gasket-sealer-38386/. 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 minutes, you would be a great candidate for the product. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!

      -BDP

  25. I have a 99 Chevy van 3500 it has started leaking from the heater core. Which is apparent cause the coolant on the floor board. The heater core was replaced new last year. I read that y’alls blue devil product is mainly for 4 or 6 cylinder engines. Will it fix the same problem on a 5.7 liter v8. Or would I need to use 2 bottles of yalls product

    1. Brian-

      Thank you for asking about your Chevy Van 3500. The BlueDevil Pour-N-Go Head Gasket Sealer is intended for use in 4-6 cylinder engines. You can still use the product on a V8, you would need at least 2 bottles to properly treat the vehicle.

      Thank you!

      -BDP

  26. I have a 2001 Dodge Caravan. In the last few days I have noticed a small puddle on the driver side floor, smell anti-freeze when I turn on the heater, have fogged up windows and only slight heat. Does that sound like a heater core leak? Which of your products will correct that problem? Will it clog up the thermostat?

    1. Richard-

      Thank you for asking about your Dodge Caravan. Based on your description, it does sound like you are experiencing a heater core leak. We recommend using the BlueDevil Head Gasket Sealer http://store.gobdp.com/head-gasket-sealer-38386/. The product does not contain any solid or particulate matter, so it is a non-clogging product. Also, as per the directions, you will be removing your thermostat and performing a cooling system flush prior to using the product. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!

      -BDP

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