What Causes A Thermostat Housing To Crack

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Thermostats in your vehicle are important parts that are often overlooked for more ‘important’ internal pieces like the engine and the transmission. Thermistor and thermostat housing is mainly crucial for two reasons – the purpose of the engine warm-up and the potential to regulate the engine operating temperature.

If it is the thermostat it can cause the engine to over heat and warp the head and/or cause mechanical damage. If it is just a leaking gasket or crack in the housing it can leak enough to cause the head to get hot and cause problems because of low coolant levels. Get it fixed cause either will cause more problems over time and both are easy fixs. If you can avoid clogging that groove in the thermostat housing, it will let all the trapped air pass right through, without having to wait for the motor to heat up & open the thermostat. I bled the hell out of it anyway, even after it warmed up, but only a number tiny bubbles made it out.

By unlocking the coolant’s circulation between the engine and radiator, the thermostat ensures that the engine reaches the necessary temperature before releasing the coolant. Thermostats and thermostat housing ensures that your car has great fuel economy, reduces the chance of engine wear and tear, and improves durability in cold weather.

Let’s find out the main function of thermostat housing, the steps of the thermostat housing replacement in your car,

The Function of Thermostat Housing

The thermostat is located between the engine and the radiator, helping regulate the heat transfer fluid flow to maintain the correct temperature. The thermostat is required in every single car to keep the engine operating at the proper temperature.

The thermostat’s duty or the thermostat housing is to impede the flow of the coolant to the radiator until the engine has reached the proper operating temperature to run correctly. When you start your vehicle after the engine heats up and gets warm over time, the coolant will also get hot within the engine.

Due to the coolant warming up and heating within the engine, the wax pellet inside the thermostat melts. Once the engine gets to around 180 degrees Fahrenheit to operate correctly, it expands and pushes the cylinder rod out of the valve’s opening. Expanding the cylinder then causes the hot coolant to flow throughout the cooling system after leaving the thermostat housing.

The radiator helps the coolant cooldown so that very hot liquid does not flow around the entire vehicle. As the coolant reaches a lower temperature, the wax in the temperature housing returns to the normal position and reduces the coolant flow. Due to the wax returning to the proper position, the thermostat and the thermostat housing work together to reduce the engine temperature.

Car Thermostat Housing Replacement

The best way that you can go about the thermostat housing repair or replacement is to refer to your service manual for your specific vehicle. This way, you won’t replace any unnecessary parts, and you won't cause any internal damage in your vehicle by fixing the wrong thermostat parts.

After referencing the service manual, you may be confused or lost as to what step is next – thankful for you; we have ten tips that can help new car owners and beginner car fixers replace the thermostat housing in many various models. Since the unit is easily accessible and can be found when working on your car, it does help that you may not need to remove any parts.

If you still need help finding the one part that you may need to remove the air cleaner assembly, then we have a step-by-step guide and procedure that you can use to replace the thermostat housing for your specific car. We have also included tips on how to work with any components that might be blocking your access to the thermostat housing.

To replace the thermostat housing and the thermostat, there are certain tools that you will need to carry out the repair and replacement. The main tools that you will need to replace the thermostat housing is a clean rag, new thermostat, gasket, gasket sealant, screwdriver, socket wrench, adjustable wrench, wire brush, and drip pan.

  • Cool the Engine

The first step in replacing the thermostat housing is to let the engine cool off. First, wait for the radiator and the engine to cool before trying to replace the thermostat. If you try to work on this apart too quickly, you can easily burn your hand or harm any other internal components. When the system is hot, the cooling system is under extreme pressure, and you will unintentionally burn yourself by releasing a huge gush of coolant.

  • Drain Some Coolant

The next step in replacing the thermostat housing is to drain the coolant in your vehicle. Drain about two quarts of coolant using the radiator drain valve before you disconnect the upper radiator hose from the thermostat shell. Disconnecting this ensures the level of coolant can drop below the thermostat housing.

What Causes A Thermostat Housing To Crack Without

If the coolant level was too high, it would splash up over the housing’s sides and cause excess friction and wear and tear. However, draining the coolant ensures the coolant stays low enough and does not separate the upper radiator hose. Coolant can cause some parts to deteriorate over time, meaning that replacing the thermostat housing ensures your car’s longevity.

  • Access the Thermostat Housing

Once the previous step has been completed, you need to remove the radiator hose from the thermostat housing in your vehicle. To find the thermostat housing in your specific car, there are a few steps you can follow to make sure you locate the correct part.

Follow the upper radiator hose to the engine – in some cars, this may require you to remove the air filter assembly to clear the parts around the thermostat housing case. You may need to disconnect the hose and the electrical sensor connector from the thermostat housing in some cases.

Once the upper hose is removed from the thermostat housing, you may find that the hose had a little trouble coming off. To break the seal, insert a flat-head screwdriver to pull off the thermostat housing so you can gain access to the part you need to remove.

  • Use the Right Tool

In this scenario, the right tool to remove the thermostat housing is a six-point wrench or a six-point socket of the correct size to loosen and remove two or three housing mounting bolts.

  • Remove the Thermostat Housing

When trying to remove the thermostat housing from your vehicle, you may need to use a rubber mallet or screwdriver handle to tap the housing and loosen it. Make sure that you do not use the wrong tool, like a wrench or regular hammer, since the thermostat housing can easily break.

  • Check Thermostat Housing Alignment

Make sure you lift the thermostat housing away from the engine, paying attention to how the thermostat is positioned inside the thermostat housing case. To check the alignment and the positioning, take notice of which direction the bleed pin is pointed to in the casing. If the bleed pin is pointing in a certain direction, make sure you install the new thermostat pointing in the same direction.

  • Clean the Surfaces

Once the thermostat is removed, cover the engine’s opening to prevent any liquid, sealant, or gasket material from leaking into the engine and causing excess friction and overheating.

To properly clean the thermostat housing and engine surfaces, you will have to use a plastic scraper to remove any sealant built-up overtime on the surfaces. Ensure that you use a plastic scraper to avoid scraping and scratching the surfaces too hard.

  • Purchase a New Thermostat

When buying a new thermostat for your thermostat housing, make sure you purchase one with the same temperature rating your car manual states for your specific vehicle. You can easily find this information in your manual, with most thermostats ranging between 192F or 195F rated thermostat.

  • Use the Right Seal

Along with getting the correct thermostat, you also need to use the proper seal to ensure a tight connection. Most new thermostats come with their own rubber seals, but you may need to buy one on your own in some cases.

You might need to apply a sealant to the new gasket for your thermostat housing – check which kind of sealant to use by referring to your service manual. In addition, some thermostats might come with a rubber seal and not a traditional gasket – in this case, apply a coat of coolant to the seal.

  • Install a New Thermostat

This is the last step in replacing the thermostat housing. You have to compare the new thermostat you just installed to the old one in this final step. Then, put each one in place along with the seal and tighten it to ensure a snug connection without any leaks.

Once the new thermostat is securely installed, look for any marking on the thermostat, indicating which end should face the radiator positioned correctly inside the thermostat housing. If you are unsure, some thermostats will have pins that help you position the thermostat within the block and the thermostat housing.

Thermostat Housing Options

  • Duralast Thermostat and Housing Assembly TA2003DL

This thermostat housing assembly is manufactured with OEM quality materials and meets the necessary safety standards set forth by an OE supplier. This thermostat housing comes with a limited lifetime warranty, weighs 2.3 pounds, has four outlets, is made of plastic and stainless steel, and includes gaskets.

Costing $97 to install on your vehicle is a reliable and durable option that works well on all cars.

  • Crown Automotive Thermostat Housing

This specific thermostat housing fits in the Jeep Wrangler, Jeep Grand Cherokee, and the Dodge Durango, including a thermostat and seal that can withstand 203 degrees. Weighing just 0.70 pounds and constructed of steel, plastic, and rubber, this thermostat housing is compatible with 3.6-liter or 3.0-liter engines.

  • Duralast Thermostat and Housing Assembly 39170

This thermostat housing is only $22 and weighs just 0.60 pounds. Being able to withstand even the most demanding and high-heat conditions, this thermostat housing is compatible with nearly all automotive cooling systems due to the copper case and wax compound construction.

  • Duralast Thermostat and Housing Assembly 51280

This Duralast thermostat housing contains a 1-year warranty and weighs just 0.45 pounds. Gaskets are included in this thermostat housing, and it contains 2 outlets. Composed plastic and stainless steel can withstand demanding automotive cooling systems, complete with the offset design, air relief valve, and OEM style seals.

Causes

Thermostat Housing Replacement

To find out the overall price for your thermostat housing repair or replacement in your vehicle, it is important that you can compare various parts available on the market today to see which one fits your vehicle's needs and your own price range.

Some of the most common options will range between $25 and $35. For example, the Motorad Engine Coolant Water Outlet comes to $27.99, with the part working well with the thermostat housing mechanism.

Dorman OE Option

In addition, the Dorman OE Solutions engine coolant thermostat housing with a limited lifetime replacement comes to $12 on the market. This is an inexpensive option that can directly replace the original thermostat housing on certain vehicle years, makes, and models. This type of thermostat housing is resistant to high heat and temperatures with durable and long-lasting construction, preventing cracking and breaking over time.

CarQuest Option

Another price option for a thermostat housing replacement is the CarQuest engine coolant thermostat housing with a limited lifetime replacement. This part is more expensive, coming in at nearly $40.

Water Neck Addition

Furthermore, if you buy a water neck to go with the thermostat housing, this can run you an average of between $15 and $20. One example of a water neck is the Mr. Gasket option, coming in at $18. This part is compatible with the thermostat housing for a complete replacement.

The Mr. Gasket water neck is a chrome-plated piece that offers a snug fit, an O-ring to prevent any water or oil leaks, and a precision die-cast for durability.

Conclusion

Now that you know the steps to replace the thermostat and thermostat housing, it is also crucial that you know the importance of this part before setting off on the placement procedure. Knowing the steps of replacing thermostat housing, the importance of this part and some good options on the market can help you make a smart decision about your vehicle.

My engine light came on and I took my 2016 Jeep Cherokee latitude in and it is still under 36000. This was just after a hard freeze and I purchased and had the vehicle less then a week. They kept it 2 weeks and then the repaired it saying it was just a simple mechanical malfunction of the thermostat housing. What would cause such a malfunction?

My car has 32000 miles.
My car has an automatic transmission.

Marvin Sunderland
22 years of experience

Hi there. If the thermostat housing was made of plastic (carbon fiber) and the temperature outside dropped below the freezing point of the cooling system, then the coolant would have froze up and expanded causing the thermostat housing to crack. Also, if the coolant has too much electrolyte causing a slight voltage in the coolant, then the chemical compound will break down causing the cooling system to eat up seals and carbon fiber.

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

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