1. How to Check BMW E90 Coolant Level

Maintaining optimal coolant levels is crucial for the efficient operation of your BMW E90. Regular checks help prevent engine overheating and costly repairs. Knowing how to check the coolant level is a vital skill for every BMW owner. This guide will walk you through the simple steps involved, ensuring you can maintain your vehicle’s health and performance with confidence.

Before embarking on this task, ensure the engine is cool to the touch to avoid burns. Locate the coolant expansion tank, typically found on the driver’s side of the engine bay. The tank is usually translucent, allowing you to observe the coolant level. Check the markings on the side of the tank to determine whether the coolant is within the specified range. If the level is below the minimum mark, it’s essential to add coolant to avoid potential engine damage.

If the coolant level is low, use a funnel to carefully add a mixture of 50% coolant and 50% distilled water to the expansion tank. Avoid overfilling the tank, as this can lead to coolant leaks and overheating. Once the level is within the specified range, replace the cap securely and monitor the coolant level regularly to ensure it remains optimal. By following these simple steps, you can effectively check the coolant level in your BMW E90, contributing to its longevity and performance.

Verifying Coolant Level Through the Expansion Tank

To accurately check the coolant level using the expansion tank, follow these steps:

1. Park the vehicle on a level surface and turn off the engine.

Allow the vehicle to cool for at least 30 minutes to prevent hot coolant from splashing or scalding.
Ensure the vehicle is on a flat surface to get an accurate reading.
Parking on an incline can skew the fluid level indicator, providing an incorrect reading.

2. Locate the expansion tank.

The expansion tank is typically a translucent plastic reservoir with markings indicating the proper coolant levels.
It is usually situated near the front of the engine compartment, close to the radiator.
Refer to your vehicle’s owner’s manual for the exact location if necessary.

3. Check the coolant level.

With the vehicle cooled and parked level, visually inspect the coolant level through the expansion tank.
The coolant level should be between the marked minimum and maximum indicators on the tank.
If the level is below the minimum, carefully add suitable coolant to bring it back within the recommended range.

4. Retighten the expansion tank cap.

Once you have added coolant, firmly tighten the expansion tank cap to maintain pressure within the cooling system.
Do not overtighten the cap, as this can damage the cap or its seal.

Identifying the Proper Coolant Type

BMW E90s require a specific type of coolant that meets the manufacturer’s specifications. Selecting the correct coolant ensures optimal engine performance and prevents damage caused by incompatible fluids.

Understanding Coolant Types

Modern automotive coolants are typically classified into two main types:

Inorganic Additive Technology (IAT): This conventional coolant contains silicates and other inorganic compounds that form a protective layer on metal surfaces. Over time, these additives can break down, leading to decreased corrosion protection and deposits in the cooling system.
Organic Acid Technology (OAT): OAT coolants utilize organic acids to inhibit corrosion and prevent scale formation. They have a longer service life than IAT coolants and are less likely to form deposits.

BMW E90 Coolant Requirements

For BMW E90s, only BMW-approved OAT coolants are recommended. These coolants meet the manufacturer’s specifications for corrosion protection, boiling point, and freezing point, ensuring proper operation of the cooling system.

Coolant Type	BMW Approved	Service Life
IAT	No	2 years/30,000 miles
OAT	Yes	5 years/100,000 miles

Utilizing the Coolant Level Sensor

Monitoring the coolant level using the coolant level sensor is a straightforward and convenient method. This sensor is typically located in the coolant reservoir or the radiator and sends a signal to the instrument cluster or dashboard to display the coolant level. Here’s how to utilize the coolant level sensor:

Locate the coolant reservoir, which is usually translucent or has a see-through window.
Check the level indicator or markings on the reservoir. These markings usually indicate “min” and “max” levels.
If the coolant level is below the minimum mark, follow the manufacturer’s instructions for adding coolant to the reservoir. Refer to the table below for recommended coolant types and ratios.
Start the engine and let it run for a few minutes to circulate the coolant and allow the sensor to detect the correct level.
Monitor the coolant level indicator on the instrument cluster or dashboard. It should now display the actual coolant level.

Vehicle Model	Coolant Type	Coolant Ratio
BMW E90 325i	BMW Blue Coolant or equivalent	50/50 Coolant to Distilled Water
BMW E90 335i	BMW Blue Coolant or equivalent	50/50 Coolant to Distilled Water

Checking the Coolant Level Using the Instrument Cluster

The BMW E90 comes equipped with a sophisticated instrument cluster that provides a plethora of information, including the coolant level. This method is the most convenient and straightforward way to check the coolant level, and it can be performed without opening the hood.

Steps:

Start the Engine: Turn on the ignition and start the engine. Allow it to run for a few minutes to warm up the coolant.
Access the Instrument Cluster Menu: Press the "BC" button on the turn signal stalk repeatedly until the "Service" menu appears on the instrument cluster display.
Select Coolant Level: Use the arrow keys on the steering wheel to navigate to the "Coolant Level" option. Press the "OK" button to select it.
Observe the Coolant Level Indicator: The instrument cluster will display a graphic representation of the coolant level. The indicator should be within the green "OK" range.
Interpret the Coolant Level:

Indicator	Meaning
Green “OK”	Coolant level is within the optimal range.
Yellow “Warning”	Coolant level is low, but not critical. Refilling is recommended.
Red “Critical”	Coolant level is dangerously low. Stop the engine and refill the coolant immediately to avoid potential damage.

Understanding the Coolant Light Warning

The coolant light warning on your BMW E90 is designed to alert you to a potential issue with the coolant system. When this light illuminates, it’s crucial to take immediate action to prevent further damage to your vehicle.

The coolant light warning can indicate a number of different problems, including a low coolant level, a coolant leak, or a problem with the coolant sensor. It’s important to have the underlying cause of the warning light diagnosed and resolved promptly to ensure optimal engine performance and prevent costly repairs.

Checking the Coolant Level

The first step in troubleshooting a coolant light warning is to check the coolant level. To do this, follow these steps:

1. Turn off your engine and allow it to cool down.
2. Open the hood and locate the coolant reservoir. The reservoir is usually located near the front of the engine and is made of translucent plastic.
3. Check the coolant level in the reservoir. The coolant level should be between the “MIN” and “MAX” marks on the reservoir.

If the coolant level is low, it’s important to add coolant to the reservoir. Use only coolant that is specifically designed for your BMW E90. Do not add water to the coolant system, as this can cause damage to the engine.

Warning Signs of Low Coolant Level

In addition to the coolant light warning, there are a number of other signs that may indicate a low coolant level:

Overheating engine
Steam or coolant leaking from the engine
Loss of heat from the heater
Coolant smell in the cabin

Diagnosing Low Coolant Levels

1. Check the Coolant Temperature Gauge:
Monitor the coolant temperature gauge on your dashboard. If the needle regularly enters the red zone, it could indicate a low coolant level.

2. Inspect Coolant Reservoir:
Open the hood and locate the coolant reservoir, typically translucent. If the coolant level is below the “MIN” mark, it’s a clear sign of low coolant.

3. Check for Coolant Leaks:
Visually inspect the hoses, pipes, and connections around the engine and radiator for any cracks, leaks, or damage. Look for puddles of coolant under the car.

4. Listen for Hissing Sounds:
If you hear a hissing sound coming from under the hood, especially when the engine is running, it could indicate a coolant leak.

5. Monitor Engine Behavior:
If the engine overheats or stalls frequently, or if there’s a noticeable loss of power, it can be a symptom of low coolant levels.

6. Check for White Smoke from Exhaust:
If you notice white smoke coming from the exhaust, it could be caused by coolant leaking into the combustion chamber.

7. Coolant Condition
Examine the coolant’s color and texture. Coolant should be a transparent green or pink liquid. If it appears murky, brown, or contaminated with rust or particles, it needs to be flushed and replaced.

Coolant Condition	Interpretation
Transparent Green or Pink	Normal
Murky or Brown	Possible contamination or overheating
Rust or Particles Present	Requires flushing and replacement

Checking Coolant Level

To check the coolant level, locate the coolant expansion tank in your engine bay. It is typically a translucent plastic container with a black cap. Look at the tank and note the coolant level. It should be between the “MIN” and “MAX” marks on the side of the tank. If the level is low, you need to add more coolant.

Replenishing Coolant if Necessary

If you need to add coolant to your BMW E90, follow these steps:

Let the engine cool down completely. This is important to avoid burns.
Locate the coolant expansion tank.
Open the black cap on the expansion tank.
Add coolant to the tank until it is between the “MIN” and “MAX” marks.
Close the black cap.
Start the engine and let it run for a few minutes.
Check the coolant level again to make sure it is still between the “MIN” and “MAX” marks.
If the coolant level is still low, there may be a leak in the cooling system. You should take your car to a mechanic for diagnosis and repair.

Coolant Type

It is important to use the correct type of coolant in your BMW E90. The recommended coolant is BMW Blue Coolant. This coolant is specifically designed for BMW engines and it provides excellent protection against corrosion and freezing.

Coolant Flush

Over time, the coolant in your BMW E90 will become contaminated with dirt and debris. This can reduce the effectiveness of the coolant and can lead to cooling system problems. It is important to flush the coolant every 30,000 miles or 2 years to keep your cooling system running smoothly.

Table of Coolant types for BMW E90

Coolant Type	Recommended for
BMW Blue Coolant	All BMW E90 models

Bleeding the Cooling System After Filling

Once you’ve refilled the coolant system, it’s crucial to bleed it to remove any trapped air and ensure optimal cooling system functionality. Here’s a detailed step-by-step guide on how to bleed the cooling system in a BMW E90:

Start the engine: With the engine running, let it idle for a few minutes until it reaches operating temperature.
Open the bleeder valve: Locate the bleeder valve on the top of the radiator or coolant expansion tank. Slowly open the valve to release any trapped air.
Check the fluid level: As you open the valve, monitor the coolant level in the expansion tank. If it drops significantly, add more coolant.
Close the bleeder valve: As soon as a steady stream of coolant flows out of the bleeder valve, close it tightly.
Repeat steps 2-4: Continue opening and closing the bleeder valve until no more air escapes and the coolant level remains stable.
Check for leaks: Once the system is bled, inspect all hoses and connections for any leaks.
Reinstall the cap: Place the cap back on the coolant expansion tank and tighten it securely.
Test drive: Take the vehicle for a test drive to ensure the cooling system is functioning properly. Monitor the temperature gauge and look for any unusual noises.
Recheck the coolant level: After the test drive, allow the engine to cool down and then recheck the coolant level in the expansion tank. Top up the fluid if necessary.

Additional Tips

Tip	Description
Use a clean cloth to open and close the bleeder valve to avoid contamination.	This helps prevent dirt or debris from entering the cooling system.
Run the heater to circulate coolant throughout the system.	This ensures even bleeding and prevents air pockets from forming.
Avoid overfilling the coolant expansion tank.	Excess coolant can overflow and cause issues when the system heats up.

By following these steps and tips, you can effectively bleed the cooling system in your BMW E90, ensuring optimal engine cooling and preventing potential issues.

Checking BMW E90 Coolant Level

Maintaining optimal coolant levels is crucial for your BMW E90’s engine health. Here’s a detailed guide to check the coolant level accurately:

1. Safety Precautions

Park the car on a level surface and allow the engine to cool down. Wear gloves and safety glasses to prevent burns or spills.

2. Locate the Coolant Reservoir

The coolant reservoir is typically located on the driver’s side, near the front of the engine compartment. It’s a transparent container with a blue or green cap.

3. Inspect the Reservoir

Check for any cracks or leaks on the reservoir. If there are any, consult a mechanic for repairs.

4. Remove the Cap

Locate the coolant reservoir cap and gently twist it counterclockwise to remove it. Be careful not to drop the cap inside the reservoir.

5. Check the Coolant Level

The coolant level should be between the “MIN” and “MAX” marks on the side of the reservoir.

6. Add Coolant if Necessary

If the coolant level is below the “MIN” mark, add a pre-mixed BMW coolant until it reaches the “MAX” mark.

7. Replace the Cap

Screw the coolant reservoir cap back on tightly to prevent leakage.

8. Start the Engine and Check

Start the engine and run it for a few minutes. Check the coolant level again to ensure it has remained within the “MIN” and “MAX” range.

9. Monitor Coolant Level Regularly

Check the coolant level regularly, especially before long trips or in hot weather conditions.

How to Check BMW E90 Coolant Level

Checking the coolant level in your BMW E90 is a simple and important task that can help prevent engine damage. Coolant helps to keep your engine cool and running smoothly. If the coolant level is too low, your engine can overheat and cause serious damage. Checking the coolant level is something that you should do regularly, especially before long trips. Here’s how to do it:

Park your car on a level surface and turn off the engine.
Allow the engine to cool for at least 30 minutes.
Open the hood and locate the coolant reservoir. It is usually made of clear plastic and has a black cap.
Check the coolant level in the reservoir. It should be between the “MIN” and “MAX” marks on the side of the reservoir.
If the coolant level is low, add more coolant until it reaches the “MAX” mark.
Replace the cap on the reservoir and close the hood.