How to Fix Your Mini’s Radiator Expansion Tank Failure From the Best Mechanics in San Jose

Minis are fun cars to drive. They are powerful and provide drivers with superior performance. They are known for being safe and reliable, but they still have their issues. If you own a Mini, you have probably heard that radiator expansion tank failure is something that you need to watch out for.

What is the radiator expansion tank?

The radiator expansion tank is also referred to as the RTE. It is a container that is used as an overflow tank. When coolant expands, this tank provides extra storage. The coolant is then recycled back through keeping the engine at optimal running temperature.


If you ever need to check your coolant level, never remove the radiator cap while the engine is hot. The coolant is under pressure, and when the cap is removed, it can spray out, causing severe burns. Always wait for your engine to cool down completely before removing the cap.

Symptoms of Radiator Expansion Tank Failure

When the radiator expansion tank begins to fail, you may experience some of these symptoms:

Rust in the radiator

When the RTE is functioning properly, you will not have rust in your radiator. If you experience rusting, you are probably facing tank failure.

Overheating Engine

Coolant is necessary to keep your engine cool. If it is not receiving the proper amount of coolant, it can overheat. If your engine overheats, turn your car off. Do not continue to drive it, because it can lead to complete engine failure.

Low Coolant Level

Your coolant needs to be at the level specified by your manufacturer's instructions. If the coolant level is low, there is a chance that your radiator expansion tank has failed or you have a coolant leak.

Coolant Leak

Leaks under your vehicle are usually easy to see if you park on a hard, flat surface. If you park on gravel, put a large piece of cardboard under your vehicle to see if you have a leak. Coolant is easily distinguished from oil. It is usually bright green, blue,yellow, red, orange, or pink. Oil is dark reddish-brown and appears almost black.

Strong Coolant Smell

Coolant has a sweet smell that is unmistakable. You should never be able to smell it inside or outside of your vehicle.

What Causes Radiator Expansion Tank Failure?

These are the most common causes of radiator expansion tank failure:

Reservoir is Cracked

When your reservoir tank cracks, it allows coolant to leak out. If the crack is small, the leak may not be noticeable at first. If the crack is large, you can lose a lot of coolant at once. Cracking can occur from old age and overheating.

The Tank Isn't Correctly Pressurized

If the tank isn't correctly pressurized, it can lead to overheating. The excess heat will damage the tank and cause it to crack.

Cap is Broken or Wasn't Properly Sealed

Issues with the cap can lead to a loss of pressure. The loss of pressure leads to overheating.

Don't Wait to Get it Fixed

If you notice any of the above symptoms happening to your Mini, don't wait to have them fixed. Failing to take care of the issues right away can lead to additional damage including complete engine failure and fire. Replacing the tank now can save you time as well as money.

Quality Service You Can Count On

If you own a Mini, you want to hire a mechanic that you know that you can trust. Don't waste your money taking your car to a dealership for service or maintenance. Our technicians are highly trained and will provide you with dealership quality service without the outrageous costs. We also have the expert equipment needed to diagnose and fix your vehicle properly.

Free Second Opinions

If you need a second opinion, bring the other company's recommendation to us. We will perform a visual inspection and either confirm or deny their recommendation. This is for visual inspections only. It does not apply to electric repairs or deciphering codes.

Contact Us Today

Fast Lane European is a Volvo, Mini, Mercedes, and BMW service and repair shop. We are located at 3585 Stevens Creek Blvd, San Jose, CA. Stop by and see us today or call to schedule your appointment at 408-985-1000.