Symptoms of a Cracked Block

Cracked BlockHaving a cracked block can give a variety of strange symptoms that can be hard to identify and diagnose.  Like many problems with your cooling system, a cracked block often can mask itself during normal operation of your vehicle and only reveal itself during certain conditions making it extremely hard to diagnose.

Having a cracked block has to do both with the normal use of the vehicle and the construction of the engine itself.  When vehicle manufacturers are designing engines, then want to make sure the engine is sturdy and able to withstand the stresses and strains that will be on it both from the combustion process and from the heating and cooling cycles the engine will go through.  On the other hand, the weight of the engine has a lot to do with how to the car performs.  A heavier engine will decrease fuel mileage due to the extra energy required to get all that weight moving from a stop.  A heavier engine can also affect the handling characteristics of a car as the added weight can affect the center of gravity and its ability to corner well.

As engine manufacturers try to balance building an engine that is both lightweight and strong they have to account for all the stresses the engine will go through.  The pressures of combustion are high, but rarely high enough to significantly affect your engine block.  The more prominent stress on an engine is the heating and cooling cycles it endures from starting and stopping the engine.  The heat comes from the combustion process and is spread to the rest of the engine through the flowing coolant.  As the metal gets warmer it expands but at different rates depending on the temperature gradients.  Combine that stress with the normal vibrations of driving, braking and accelerating you can get huge stresses in different parts of your engine block.

These stress, after many miles, can lead to failures and small cracks to form.  Engine blocks rarely crack quickly.  The crack usually starts as small cracks that leak only a tiny amount of fluid and only when the engine is hot and the cooling system is pressurized.  Since most engine blocks are cast iron, once a crack has started, it is almost impossible to stop.  Because of the way the metal molecules settle into a lattice as the block is cast, cracks can easily propagate through the metal once they’re started.  This means that if you do have a cracked block, the leak will often get bigger quickly.

This leads us to one of the main symptoms of a cracked block.  A cracked block will almost always cause a cooling system leak and start very slowly.  Sometimes it will be so slow that you will only be able to notice the leak when your car is warm and it will just look like a small amount of steam.  As you continue to drive the heating and cooling cycles will enlarge the crack until you notice more steam, then possible drips of coolant and eventually a leak that will lose water whether the engine is warm or cold.

The other symptom of a cracked block that can be confusing is that the crack is often in the corner of a gusset or near a ridge in the block where the metal goes from thick to thin.  These areas are often very difficult to see without a mirror and flashlight or by removing the block.  These areas are often away from other coolant hoses and can be confusing.

If you discover a cracked block in your vehicle, don’t worry!  You may not even need to take your car to the mechanic’s shop to stop the leak.  BlueDevil Radiator and Block Sealer is a safe and easy to use sealing agent that can repair a crack in your cast iron or aluminum engine block without using tools.

For more information about BlueDevil Radiator and Block Sealer, click on the banner below!!
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You can find BlueDevil Radiator and Block Sealer at any of our partnering local auto parts retailers 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
  • Fisher Auto Parts stores
  • Auto Plus Auto Parts stores
  • Hovis Auto & Truck Supply stores
  • Salvo Auto Parts
  • Advantage Auto Stores
  • Genuine Auto Parts stores
  • Bond Auto Parts stores
  • Tidewater Fleet Supply
  • Bumper to Bumper Auto Parts
  • Any Part Auto Parts
  • Consumer Auto Parts

Pictures Provided By:

cracked_block.jpg – By Daseaford – Licensed by Getty Images – Original Link

43 responses to “Symptoms of a Cracked Block

    1. Frank-

      Yes, the BlueDevil Radiator & Block Sealer, and both of our BlueDevil Head Gasket Sealers are safe and compatible to use on aluminum blocks. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!

      -BDP

  1. My mechanic says that probably I have cracked block. The symptoms are presence of small amount of engine oil in coolant but no coolant is in engine oil as the dipstick and oil cap shows no signs of coolant in the oil. Can this product help to overcome problem?

    1. Hello i am having this exact same problem & i am wondering if you can tell me your solution my name is Aynice can you please contact me at 214-574-8407

    2. Blown head gasket more than likely. Cracks in blocks usually occur in the cylinder walls themselves. Unless the vehicle did not have anti-freeze in it and froze during the winter, the cracked block would not cause oil to get into the coolant.

  2. My 3.2 ltr 4M41 turbo diesel Pajero Exceed 2006 will start and run normal after the engine heats up it blows white smoke could this be the EGR valve.

    1. Simon-

      Thank you for asking about your Pajero Exceed turbo diesel. Unfortunately, white smoke coming from the exhaust pipe is a tell-tale sign of a blown head gasket. Are you noticing a loss of water/coolant? Is the vehicle overheating at all? Please contact our technical support line at 888-863-0426 so that we can get a little better understanding of the vehicle’s condition and be able to make any appropriate recommendations.

      Thank you!

      -BDP

  3. I have a 2000 Chevy Cavalier. It overheated accordi h to the dashboard gage. I stopped immediately at a gas station and turned the car off. There was no smoke or steam. The coolant bottle was empty. I filled it 5 days prior. There was no leaking in my garage nor my parking space at work. ????

    1. CAM-

      Thank you for asking about your Chevy Cavalier. Please contact our technical support line at 888-863-0426 so that we may get a little better understanding of the vehicle’s condition and be able to make any appropriate recommendations.

      Thank you!

      -BDP

  4. Hello,

    I would wish to purchase the Radiator & Block Sealer (item number #00205) but each time I tried to confirm the payment, I got the following error message:

    “Something went wrong when trying to process your payment. Please review the error message and try again:
    This transaction has been declined”

    For your information, I am from Mauritius Island.

    Could you please suggest ways to properly confirm the payment?

    Thank you.

    Jonathan

    1. Jonathan-

      Thank you for your interest in the BlueDevil Radiator & Block Sealer. Our credit card processor is very sensitive to international orders to prevent from fraud.  When placing the order make sure your billing address matches exactly what you have on file with your credit card company. Otherwise, you may contact us at 888-863-0426 to place an order over the phone.

      Thank you!

      -BDP

  5. I am having a problem with oil pressure. it starts off good @60lps but as the engine warms up it drops to 8-10lps at idle. the block is a 454 rebuilt twice but has the same issue. everything was checked except the block. after the first rebuild I had some overheating issues which hopefully have been resolved. could an oil galley have cracked to cause the problem.what are your thoughts

    1. Mike,

      Thanks for your question about your 454 oiling issues. It is possible you’ve got a crack in the blog but the only way to discover that problem would be to pull the engine, tear it down, and have it magnfluxed. Before you try all that it may be worth installing a high pressure/volume oil pump or trying a slightly higher viscosity oil. If the engine has been rebuilt twice it’s possible that you simply need to run a thicker oil to compensate for larger clearances depending what type of machine work has been done.

      Thanks again for your question!
      -BD Auto Pro

  6. Hello,
    My 2000 subaru outback just recently started overheating after the coolant froze and we failed to notice before driving (northern MN winters!). I brought it to a mechanic and they replaced the coolant, but the engine still overheats. It overheats, but also cools back down very quickly. They thought it was a blown head gasket but for some reason (call it intuition) I am hesitating to believe this. Plus I don’t notice any of the tell tale signs that it is blown head gasket. So I am wondering if it could be a cracked engine block? I would really appreciate any feedback you may have. Thank you.
    -Colin

    1. Colin-

      Thank you for asking about your Subaru Outback. Are you noticing any water/coolant loss? It is possible that you are getting combustion/exhaust gases pumping back into the cooling system.  You can use a “Block Dye Tester” to confirm whether or not that is the case.
      If that is the case, BlueDevil Head Gasket Sealer will still work if your vehicle is getting combustion/exhaust gases blowing into the cooling system and creating pressure.  To give yourself the best overall chance of BlueDevil working successfully, in addition to the directions, you should remove the spark plug from the cylinder with the leak; this will be the spark plug from the cylinder with the low compression reading.  If you are not sure which one that is, you may pull all of the spark plugs and will notice one will have a white-crystal-like substance on it and/or may look dirty; this is the plug you should pull.  Leave that plug out for the 50 minute idle in order to relieve the pressure from building up and thus allowing the product to seal properly.  Be sure to follow the guidelines for the proper amount to use based on the size of your cooling system.

      Thank you!

      -BDP

  7. My car finishes it’s water after a month, I changed the head gasket, water pump and thermostat and I can’t seem to find any leaks. Which blue devil product do you recommend ?

    1. Mure-

      Have you noticed any other symptoms with the vehicle besides losing water? Please contact our technical support line at 888-863-0426 so that we an get a better understanding of the vehicle’s condition and be able to make any appropriate recommendations.

      Thank you!

      -BDP

        1. Kevin-

          The product is intended for a leak that is seeping or a lightly dripping. In order to get the benefit of using the product, the vehicle will need to be able to idle for 45 minutes without overheating or stalling out, and you shouldn’t be losing more than about a quart of water/coolant during an hour of idle.

          Thank you!

          -BDP

  8. My 1999 Ford f150 was running good, let a family member use it and they never told me I had a coolant leak until I was driving it to work 1 morning and it wouldn’t let me drive more than 20 miles per hour. Let a mechanic look at it and he said when the anti freeze leaked out they just replaced it with water instead of fixing the freeze plug and putting antifreeze back in it so the water froze during winter causing the ice to expand and crack the block what can I do about this situation. Thank you in advance.

    1. Tony-

      Thank you for asking about your Ford F-150. To confirm, are you losing water/coolant from the block and the freeze plugs as well? How quickly are you losing water/coolant? Please contact our technical support line at 888-863-0426 so that we may get a little better understanding of the vehicle’s condition and be able to make any appropriate recommendations.

      Thank you!

      -BDP

  9. I have a 2001 Ford Taurus. It is leaking coolant from, what looked like, the lower radiator hose near the water pump. I replaced the lower hose, put everything back together with fresh coolant and started it. Still leaking. I can’t see where it’s coming from. I replaced the water pump a few years ago so I’m thinking if it were going to leak anywhere from the water pump, it would have done it before now. I’m thinking it maybe a crack in the engine near the water pump. Or the timing cover gasket is bad and it’s leaking there. I just can’t tell for sure because it’s to tight to see. Should I use your product before I take it to a shop or just take it in? I mean, will it harm anything if I try it first? Thanks.

    1. Tom-

      Thank you for asking about your Ford Taurus. Based on your description, we recommend using the BlueDevil Head Gasket Sealer. AS long as you are not losing coolant too quickly, and the vehicle can maintain idle for a full 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

  10. I have a 1985 toyota corolla I noticed coolant leaking at my no3 spark plug port what product do you recommend to fix the problem.

    1. Alfred-

      Thank you for asking about your Toyota Corolla. Based on your description, we recommend using the BlueDevil Head Gasket Sealer. You may use either of the Head Gasket Sealers that we manufacture. The “Pour N Go” (16 oz./white label) is a less concentrated formula that does not require the removal of the thermostat or a flush of the cooling system prior to use. Whereas the “Mechanic Approved” (32 oz./yellow label) requires both the removal of thermostat and a flush before applying the product; the 32 ounce is the more concentrated formula.
      The product with the yellow label will give you best overall results as long as you can remove the thermostat and flush the system prior to use. With the use of either product, be sure to follow the guidelines for the proper amount to use. Based on your capacity, you will be using 16 ounces of BlueDevil with either product.

      Thank you!

      -BDP

  11. Dear Sir, my 318 BMW engine overheat. I have done top overhaul, service the radiator, change the switch, sensor, water pump, thermostate even run the radiator fan direct but still overheat. There’s no leaking water or engine oil.
    What seems to be the problem. Any of your product could help?

    1. Mohd-

      Thank you for asking about your BMW. Based on your description, it seems that you have addressed everything you would have needed to with an overheating vehicle. Another possibility is that the cooling system is building up pressure and there is a restriction of water circulation. Have you noticed a bubbling or a boiling over in the system? Are you getting any codes for engine misfire or is the vehicle idling roughly? Please contact our technical support line at 888-863-0426 so that we can get a little better understanding of the vehicle’s condition and be able to make any appropriate recommendations.

      Thank you!

      -BDP

  12. I have a 93 chrysler New Yorker salon. I replaced the radiator, the thermostat and have noticed a small crack in top of the engine by the thermostat. It takes a little bit for the car to hear up but that is where I see the steam coming from. Will your BlueDevil radiator and block dealer work to that?

    1. Kelly-

      Thank you for asking about your Chrysler New Yorker. As long as you are not losing water/coolant too quickly, you would be a good candidate for the BlueDevil Radiator & Block Sealer. If the system has not been chemically flushed recently, we recommend flushing the system with the BlueDevil Radiator Flush to ensure the system is clean.

      Thank you!

      -BDP

  13. I have a 2008 chevy impala Lt police edition… I took it in about 3wks ago because I kept hearing a loud whining noise whenever I started the car and also when I turned the steering wheel. I was told that I needed a power steering pump which I did have replaced and every since then my car has been leaking a lot of fluid. I took it back and was told that the hose was loose so they tightened it and replenished the fluids but if I tell you that the leak seems worse than before and mind you my vehicle was not leaking at all prior to having the power steering pump replaced. Took it back again because still leaking fluid then I was told that I needed a valve intake cover and oil pan gasket but my car is not leaking oil. Fast forward to a few days ago had the engine steamed cleaned so different mechanic can see where leak is coming from. I was told that my car is leaking oil and that I have a crack in my block but the fluid that is leaking out is not oil it is not it is power steering fluid I know this only because in a weeks time I have used a entire bottle of power steering fluid and my oil level is at 87% after having oil change same time as power steering pump. There is no smoke coming from tailpipe the car starts right up and stays started it is not over heating or running hot. taking it to another mechanic asap for I can not keep missing and leaving work because of this issue.

    1. Felicia-

      Thank you for asking about your Chevy Impala. Based on your description, we agree that you may want to take the vehicle to another mechanic for a second opinion. It is possible that you are losing both oil and power steering fluid, however, it is strange that the first mechanic didn’t mention anything about the loss of power steering fluid. Hopefully, you get a better answer from the second mechanic.

      Thank you!

      -BDP

  14. 2006 Pontiac Montana SV6. What a nightmare! I have an overheating issue that persists despite bleeding of cooling system, Super flush, new water pump, new thermostat. No visible signs of a head gasket. In earlier comments you mentioned misfire, which was a code that came up that I told is unrelated to the issue. Is it possible that I have a cracked block? Is the misfire an indication? Not sure what to do at this point! Please help!

    1. Shari-

      Thank you for asking about your Pontiac Montana. Based on your description, it is possible that you are getting combustion/exhaust gases pumping back into the cooling system. You can use a “Block Dye Tester” to confirm whether or not that is the case.
      BlueDevil Head Gasket Sealer will still work if your vehicle is getting combustion/exhaust gases blowing into the cooling system and creating pressure. To give yourself the best overall chance of BlueDevil working successfully, in addition to the directions, you should remove the spark plug from the cylinder with the leak; this will be the spark plug from the cylinder with the low compression reading. If you are not sure which one that is, you may pull all of the spark plugs and will notice one will have a white-crystal-like substance on it and/or may look dirty; this is the plug you should pull. Leave that plug out for the 50 minute idle in order to relieve the pressure from building up and thus allowing the product to seal properly. Be sure to follow the guidelines for the proper amount to use based on the size of your cooling system.

      Thank you!

      -BDP

    1. Mac-

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

      Thank you!

      -BDP

  15. Can’t figure it out my 85 Lincoln Town car is pouring water out of the back of the motor as soon as I put it in the radiator it ran hot and I let it cool but just sitting there it’s pouring water out as fast as I put it in

    1. Jesse-

      Thank you for asking about your Lincoln Town Car. Unfortunately, it sounds like you are losing water a little too quickly for our products to be successful. A hard part repair may be your best option.

      Thank you!

      -BDP

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