While manufacturers have developed new long-life coolant formulas, one has to question if these coolants are truly up to the task of protecting the engine for up to a decade. Considering that corrosion is a permanent ordeal, owners agree that the small cost of a regular cooling system flush pales in comparison to any potential harm that could arise from extended coolant service intervals.
Although many manufacturers are now using "extended-life" coolants in their vehicles, most experts agree that regular cooling system maintenance is essential to the health of your vehicle. Engine coolant (a.k.a. antifreeze) serves a multitude of functions, including raising the boiling point of water, providing freeze protection during the cold winter months, and fighting scale as well as corrosion inside of the cooling system. Coolants contain many additives, which makes this kind of protection possible; however, these additives break-down with time and use, and cannot adequately protect the engine forever. Considering the huge role coolant plays in the operation of any engine, many agree that there is no such thing as over-maintaining your cooling system, even if the coolant is rated at 10+ years or 100,000 miles. This article will outline the procedure for flushing the cooling system on JK Jeep Wrangler models.
Materials Needed
Refilling the cooling system with the correct coolant is of key importance when performing a cooling system flush on your JK. The 2007 to 2012 Wranglers use a HOAT (Hybrid Organic Additive Technology) coolant, whereas 2013+ Wranglers have switched to a OAT (Organic Additive Technology). Chrysler insists that these coolants are NOT interchangeable, and any mixing of the two can result in accelerated cooling system corrosion and overheating. HOAT formulas are a bit more common and are available at local parts stores as well as the dealership. Conversely, the new OAT coolant is currently supplied only through dealerships. In either case, two gallons of concentrate coolant (undiluted) will be plenty to refill your cooling system.
Figure 1. OAT vs HOAT coolant.
Pro Tip
Notice the color difference in the two different coolant formulas. This is to prevent accidental mixing of the two.
Step 2 – Drain coolant
Warning!
Before attempting to drain the coolant, ensure the engine is cool to the touch because hot coolant can cause severe injuries if it comes in contact with your skin.
To best access the radiator drain cock, removal of the skid plate is recommended. Simply remove the "scrivet" type fasteners by using a Phillips screwdriver to back out the screws. These fasteners have a tendency to spin when attempting to loosen the screws, so holding a flat screwdriver or similar tool under the base of the fasteners will prevent them from spinning. Newer model Wranglers will have plastic push-pins instead of the scrivet fasteners.
Figure 2. Skid plate removal.
Similarly, the front grille can be removed to gain access to the radiator drain cock as well. Remove the push-pins/scrivet fasteners across the top of the grille and disconnected the indicator lamps. With the top of the grille loose, pull out and upwards to release the lower clips securing the bottom of the grille. Set grille aside.
Figure 3. Grille removed.
Attach a piece of vinyl hose to the radiator drain cock located at the bottom of the radiator on the passenger's side.
Figure 4. Hose attached to radiator drain cock.
Figure 5. Diagram of drain cock location.
Open the drain cock to begin draining the coolant. The drain cock only needs to be loosened approximately 1/2 turn to allow coolant to drain. Have a catch pan handy to collect the emerging coolant.
Figure 6. Coolant draining into catch pan.
Removing the radiator cap and coolant expansion tank cap will introduce air into the system, allowing the coolant to drain at a much quicker rate.
Figure 7. Radiator and expansion tank cap removal.
While the coolant is draining, it is recommended that the coolant expansion tank be drained of any coolant. This can be accomplished by sucking the coolant out with a vacuum pump or by simply removing the tank and dumping the coolant.
Figure 8. Coolant expansion tank removal.
When the coolant has finished draining, tighten the drain cock.
Pro Tip
Slightly lifting the driver's side of the vehicle with a floor jack can allow additional coolant that would otherwise remain in the system to drain out of the radiator.
Step 3 – Fill with water and start car
Although the cooling system capacity is just a touch over three gallons, only one to 1.5 gallons (including expansion tank coolant) can be drained from the cooling system. To remove the rest of the old coolant, several flushing cycles will be needed.
Figure 9. Filling system with distilled water.
Pro Tip
Feeling the top radiator hose can indicate when the thermostat has opened and coolant is circulating the entire cooling system.
Step 4 – Drain water
Figure 10. Color of coolant after each successive flush.
Step 5 – Fill with new coolant
After you have completed flushing the system for the final time, proceed with filling the system with new coolant.
It is best to check the coolant level after a day or two of driving. This will allow any residual air trapped in the system to "burp" and additional coolant to be added if necessary.
Featured Video: How to Flush Radiator Wrangler JK
Although many manufacturers are now using "extended-life" coolants in their vehicles, most experts agree that regular cooling system maintenance is essential to the health of your vehicle. Engine coolant (a.k.a. antifreeze) serves a multitude of functions, including raising the boiling point of water, providing freeze protection during the cold winter months, and fighting scale as well as corrosion inside of the cooling system. Coolants contain many additives, which makes this kind of protection possible; however, these additives break-down with time and use, and cannot adequately protect the engine forever. Considering the huge role coolant plays in the operation of any engine, many agree that there is no such thing as over-maintaining your cooling system, even if the coolant is rated at 10+ years or 100,000 miles. This article will outline the procedure for flushing the cooling system on JK Jeep Wrangler models.
Materials Needed
- Phillips and flat screwdrivers
- Catch pan
- Pliers
- Length of 1/4" hose
- 2 gallons of coolant
- 3-5 gallons distilled water
- Floor jack (optional)
- Vacuum pump (optional)
- Ratchet with metric socket set (optional)
Refilling the cooling system with the correct coolant is of key importance when performing a cooling system flush on your JK. The 2007 to 2012 Wranglers use a HOAT (Hybrid Organic Additive Technology) coolant, whereas 2013+ Wranglers have switched to a OAT (Organic Additive Technology). Chrysler insists that these coolants are NOT interchangeable, and any mixing of the two can result in accelerated cooling system corrosion and overheating. HOAT formulas are a bit more common and are available at local parts stores as well as the dealership. Conversely, the new OAT coolant is currently supplied only through dealerships. In either case, two gallons of concentrate coolant (undiluted) will be plenty to refill your cooling system.
Figure 1. OAT vs HOAT coolant.
Pro Tip
Notice the color difference in the two different coolant formulas. This is to prevent accidental mixing of the two.
Step 2 – Drain coolant
Warning!
Before attempting to drain the coolant, ensure the engine is cool to the touch because hot coolant can cause severe injuries if it comes in contact with your skin.
To best access the radiator drain cock, removal of the skid plate is recommended. Simply remove the "scrivet" type fasteners by using a Phillips screwdriver to back out the screws. These fasteners have a tendency to spin when attempting to loosen the screws, so holding a flat screwdriver or similar tool under the base of the fasteners will prevent them from spinning. Newer model Wranglers will have plastic push-pins instead of the scrivet fasteners.
Figure 2. Skid plate removal.
Similarly, the front grille can be removed to gain access to the radiator drain cock as well. Remove the push-pins/scrivet fasteners across the top of the grille and disconnected the indicator lamps. With the top of the grille loose, pull out and upwards to release the lower clips securing the bottom of the grille. Set grille aside.
Figure 3. Grille removed.
Attach a piece of vinyl hose to the radiator drain cock located at the bottom of the radiator on the passenger's side.
Figure 4. Hose attached to radiator drain cock.
Figure 5. Diagram of drain cock location.
Open the drain cock to begin draining the coolant. The drain cock only needs to be loosened approximately 1/2 turn to allow coolant to drain. Have a catch pan handy to collect the emerging coolant.
Figure 6. Coolant draining into catch pan.
Removing the radiator cap and coolant expansion tank cap will introduce air into the system, allowing the coolant to drain at a much quicker rate.
Figure 7. Radiator and expansion tank cap removal.
While the coolant is draining, it is recommended that the coolant expansion tank be drained of any coolant. This can be accomplished by sucking the coolant out with a vacuum pump or by simply removing the tank and dumping the coolant.
Figure 8. Coolant expansion tank removal.
When the coolant has finished draining, tighten the drain cock.
Pro Tip
Slightly lifting the driver's side of the vehicle with a floor jack can allow additional coolant that would otherwise remain in the system to drain out of the radiator.
Step 3 – Fill with water and start car
Although the cooling system capacity is just a touch over three gallons, only one to 1.5 gallons (including expansion tank coolant) can be drained from the cooling system. To remove the rest of the old coolant, several flushing cycles will be needed.
- Fill the radiator with distilled water. While a regular garden hose with tap water can be used, distilled water is preferred as it contains no minerals. Since the system cannot be entirely drained, a portion of water will remain in the system and eventually be mixed with the coolant concentrate.
- Fill the coolant expansion tank approximately 1/3 of the way with distilled water.
- Leaving the radiator cap off, start the vehicle and turn the heater to the fully 'ON' position.
- While the car is idling, top off the radiator as needed before installing the cap.
- Allow the car to run for approximately 5-10 minutes to allow it to reach full operating temperature. Once warm, shut the car off.
- Allow the engine to become cool to the touch before proceeding to Step 4.
Figure 9. Filling system with distilled water.
Pro Tip
Feeling the top radiator hose can indicate when the thermostat has opened and coolant is circulating the entire cooling system.
Step 4 – Drain water
- Now that the distilled water has mixed with the old coolant in the system, proceed with draining the radiator as outlined in Step 2.
- Each drain interval will produce cleaner water containing less coolant.
- Once the water has drained, proceed with refilling the system with distilled water as outlined in Step 3 and run the vehicle through another heat cycle. It is recommended that the system be flushed at least two to three times. Some individuals prefer to flush until the draining water is completely clean.
Figure 10. Color of coolant after each successive flush.
Step 5 – Fill with new coolant
After you have completed flushing the system for the final time, proceed with filling the system with new coolant.
- With the radiator drain cock closed and tight, fill the radiator with concentrate coolant. Do not use a pre-diluted 50/50 coolant mix, as this will disrupt the coolant ratio and not provide enough corrosion, freeze, and boil-over protection.
- The radiator should accept approximately one gallon of coolant.
- Fill the coolant expansion tank with concentrate coolant until full and close the cap.
- Start the car and top off the radiator with coolant as needed before installing the radiator cap. Let it idle for about 10 minutes, ensuring that the car gets warm enough to flip the thermostat and the car gets up to operating temperature. While the car is running, check for coolant leaks.
- Re-install the skid plate or grille if necessary.
- Properly dispose of old coolant.
It is best to check the coolant level after a day or two of driving. This will allow any residual air trapped in the system to "burp" and additional coolant to be added if necessary.
Featured Video: How to Flush Radiator Wrangler JK