Subarus are generally reliable, dependable vehicles, and their drivers tend to be incredibly loyal. However, one common concern people have with Subarus is the vulnerability of the head gasket, and this worry may stop them from buying one. Our Subaru repair company is taking a closer look at this issue, breaking down what the head gasket is, signs there’s an issue, and which models are most likely to be affected.
What Is the Head Gasket in a Subaru?
First, let’s look at what the head gasket does and what makes it important. Your engine is divided into two sections:
1. The engine block where the pistons and cylinders are;
2. The cylinder head where the valves, spark plug, and cam shaft are located.
Between these two sections is the head gasket. Its role is to seal the internal combustion process within the engine block while allowing coolant and oil to move separately through the engine to cool and lubricate the components.
What Causes a Blown Head Gasket
The gasket experiences expansion, contraction, warping, and friction during daily use, which puts wear on the area. However, in normal use, the gasket should hold up for a long period of time. The most common cause of a blown head gasket is an overheated engine caused by a lack of coolant in the radiator. The heat of the cylinder head and engine block expand, pinching and contracting against the head gasket so that it can’t maintain the proper seal.
The less likely cause of a blown head gasket is pre-ignition or detonation. The internal combustion within the engine should occur when both valves are closed while the piston is at the top of the power stroke. When it fires early, the fuel and air mixture is incorrect and can create a knocking sound. Over time, this can create wear and excess heat, leading to a malfunction.
Signs Your Subaru’s Head Gasket Is Damaged
The head gasket keeps the coolant passages sealed, so if it blows, the coolant enters the cylinders and creates the following conditions:
- Excess smoke coming out of the tail pipe - may be white, blue, or gray;
- A bubbling sound or visible bubbling in the radiator and coolant reservoir;
- White streaks or a chocolate milk look to the vehicle’s oil;
- Oil and coolant leaking out of the gasket;
- Loss of engine power;
Overheating and a loss of power are the two clearest signs the head gasket in your vehicle is damaged.
Is Your Subaru at High Risk for a Gasket Issue?
The good news is that not every Subaru is equipped with a faulty gasket. It’s primarily an issue that affected vehicles fitted with the 2.5-liter SOHC engine which tends to overheat more often than other models. The specific models more susceptible include:
- Foresters from 1999 - 2010;
- Imprezas from 1999 - 2011;
- Outbacks from 2000 - 2011;
- Legacy from 2000 - 2009;
- Baja from 2003 - 2005;
The engines in these cars are “boxer-style,” so they lay flat and the pistons move laterally. While this improves the handling, because the pistons sit lower in the vehicle, fluids can pool near the gaskets which can erode the seals.
Schedule Service at Our Raleigh Subaru Repair Shop Today
If you have a vulnerable vehicle, you may want to consider bringing it in to check the condition of the head gasket. If it blows out while you’re driving, it’s important to avoid driving it and bring it in for repairs as soon as possible to avoid continuing to overheat the engine and causing significant damage. Schedule service today by calling us at 919-324-3019 or filling out our appointment scheduling form.