Does Power Steering Fluid Expand When Hot?

Do you want to know how temperature affects the volume and performance of power steering fluid? Similar to most other automobile fluids, the power steering fluid expands when heated and contracts when cooled. Although you have the answer to your initial question, there is much more to learn about this topic. Let’s dig deeper and find out.

Does Power Steering Fluid Expand When Hot?

Yes, the power steering fluid expands when it gets hot. This is a common characteristic of most fluids, including power steering fluid, due to their molecular behavior. When heated, the molecules within the power steering fluid gain energy and move more vigorously, causing them to spread out and increase the overall volume of the fluid. 

However, what you need to understand is that the expansion we explained above is not something you need to worry about. This expansion is important for the power steering system because it helps maintain the proper pressure levels within the system.

Let us explain:

As the fluid heats up and expands, it fills the available space in the power steering system. This is beneficial for proper lubrication to help the functionality of the components within the power steering system.

In addition, the power steering fluid expansion also helps maintain a consistent level of pressure. If the power steering doesn’t get hot and expand, the system will fail to provide power assist, and you will feel difficulties in steering the vehicle.

Although the power steering fluid getting hot and expanding is normal and common behavior, excessive heat can lead to several problems within the power steering system which we will explain later in the article. 

What Happens If the Power Steering Fluid Gets Too Hot? 

As we mentioned the power steering does get hot during the vehicle operation. However, if it is too hot, the below-mentioned problems will arise. 

Power Steering Fluid Breakdown

Excessive heat can lead to a chemical breakdown of power steering fluid, known as thermal degradation. This occurs when the molecules in the fluid absorb too much energy from the heat, causing them to break apart.

This process can be detrimental to the power steering system, as it can create byproducts such as sludge, varnish, and acids, which can lower the quality of the fluid.

As the quality of the power steering fluid decreases, its lubrication capability diminishes, making it less effective at reducing friction. This increased friction can lead to accelerated wear within the system.

Components such as the power steering pump, rack, and hoses can be adversely affected by this degradation.

Power Steering Fluid Leaks

When the power steering fluid gets too hot, it can lead to the deterioration of seals and gaskets within the power steering system. The issue is, that seals and gaskets play a pivotal role in keeping the integrity of the power steering system. 

Rubber parts of these components can get damaged due to this excessive heat leading to cracks and leaks. When there are leaks in the power steering system, it will not have sufficient hydraulic pressure for the operation. You will feel a stiff steering wheel and even the power steering assistance warning on the dashboard. 

Foaming of Power Steering Fluid

High temperatures can cause the power steering fluid to foam, which means that air bubbles are mixed into the fluid. Air bubbles in the power steering fluid are something that you should avoid at all costs. Let me explain why.

When there are air bubbles in the power steering fluid, it can create a gurgling noise as the fluid runs through the power steering system. This noise can be quite loud and noticeable inside the vehicle, especially when you turn the steering wheel.

The noise caused by air bubbles in the power steering fluid is not dangerous in itself. It’s more of an indicator of a potential issue within the power steering system. This gurgling noise may go away when the fluid cools down, but if it persists, you should visit a mechanic to fix the root cause of the issue.

You can read our guide on “Is power steering fluid supposed to bubble?” for more info.

Overheating

In extreme cases, the high temperature of the power steering fluid can lead to the overheating of components such as the pump and rack. This can result in component failure and the need for costly repairs.

How to Check the Power Steering Fluid Expansion Level?

You can get a fair idea about the expansion level of the power steering fluid by following these steps.

To check the expansion level of the power steering fluid, start by parking the vehicle on a level surface and letting the engine cool down. Locate the power steering fluid reservoir and open the cap to inspect the fluid level, noting the cold level.

Start the engine and let it run for a few minutes to warm up the fluid. Turn the steering wheel from lock to lock to circulate the fluid, then shut off the engine and wait a few minutes for the fluid to settle. Open the cap again and check the fluid level, noting the hot level.

Compare the cold and hot fluid levels to see if there is a significant increase, which could indicate overfilling or other issues.

Additionally, inspect the color and condition of the fluid, as well as the power steering system for leaks or damage. If you’re unsure, consult a professional mechanic for further inspection.

Why Does Power Steering Fluid Expands Too Much?

As you already know by now, the power steering fluid can expand too much due to excessive heat. In addition, the same can happen if you overfill the power steering reservoir as there is too much oil in the system.

Moreover, the power steering fluid contamination, using the wrong fluid, or existing issues in the power steering system can also contribute to too much expansion of the power steering fluid.

What to Do If the Power Steering Fluid Expansion Is Significant?

If you find that the power steering fluid has expanded significantly, indicating a potential issue, we recommend trying the below-mentioned checks.

Check the Power Steering Fluid Level

First, ensure that the power steering fluid level is within the recommended range. The fluid level should fall between the minimum and maximum markings on the reservoir when the engine is cold and the vehicle is parked on a level surface.

If the fluid is overfilled, it can lead to excessive expansion. If the level is too high, you may need to remove some fluid to bring it back to the correct level.

Inspect for Leaks

Check the power steering system for any signs of leaks, as power steering fluid leaks can cause the fluid level to drop and bring air to the system. 

Check Fluid Condition

Inspect the color and condition of the power steering fluid. If the fluid appears dark, cloudy, or contaminated, you need to flush the power steering fluid and replace it.

If you’re unsure about the cause of the significant fluid expansion the best thing is to consult a mechanic at your earliest as they can diagnose the issue and recommend the appropriate repairs or maintenance.

At What Temperature Does Power Steering Fluid Expand? 

Power steering fluid typically expands when exposed to high temperatures, but the exact temperature at which this occurs can vary depending on the type of fluid and its composition. In general, power steering fluid can withstand a high range of temperatures without significant expansion and lead to the issues that we described as dangerous.

Hot weather can cause the engine and surrounding components to heat up, including the power steering system. This can elevate the temperature of the power steering fluid. In addition, if you are continuously driving on winding roads that require heavy steering, the power steering system is bound to get hotter. 

What is the Ideal Power Steering Fluid Temperature at Operation?

The ideal operating temperature for power steering fluid typically ranges from 175°F to 220°F (79°C to 104°C). Operating within this temperature range ensures that the fluid flows smoothly and maintains its lubricating and hydraulic properties.