Head Gasket Failure
You all know by now that we are huge Subaru fans. Being here in Northern Utah, Subaru’s AWD just makes a lot of sense. They are great cars that if maintained properly, will give you many miles of reliable service. That being said, your Subaru does have a few common failures to watch out for. The most common failure is a head gasket.
The main reason why Subaru head gaskets are common to fail is simply due to metal expansion. The engine block and cylinder heads on the Subaru engines are made of aluminum. The aluminum cylinder heads and sealed to the aluminum engine block utilizing a metal cylinder head gasket that is fairly thin. The cylinder heads are also sealed to the engine block using metal cylinder head bolts. As you drive your car, the engine reaches temperatures as high as 230 degrees during normal operation. Then once you turn your vehicle off, the engine cools to whatever the temperature is outside. Here in Ogden, Utah, that can be well below freezing. The constant heating and cooling of the engine allow the metal materials of the engine block, cylinder heads, cylinder head bolts, and cylinder head gaskets to all expand and contract. Seeing as the engine block, cylinder heads, cylinder head bolts, and cylinder head gaskets are all comprised of different shapes and materials, they also expand and contract at slightly different rates. This eventually leads to the cylinder head gaskets failing to seal properly.
Top signs you Subaru is due for cylinder head gaskets
Subaru head gaskets typically show us they have failed in three different ways.
Leaking coolant externally – If your head gasket fails along the exterior sealing surface, it will allow coolant to leak from the area where the cylinder head seals to the engine block.
Leaking oil externally – The engine block and cylinder heads have several oil galleys to allow oil to flow to valvetrain components. If the cylinder head gasket fails towards the exterior of one of the oil galleys, you will be able to find an external oil leak.
Leaking coolant internally – This is usually the most common failure. If the cylinder head gasket fails around one of the internal cylinder seals, it will allow coolant to enter one or more cylinders. This creates a good amount of white smoke from the exhaust.
If you were to call 10 different shops to discuss the cost of Subaru cylinder head gasket replacement, you will likely get 10 very different answers. It is important that you take your car to the Subaru specialist that you trust and make sure it is diagnosed and estimated properly before moving forward with any repairs. Here is what we typically include in the estimate when we are doing Subaru head gasket replacements.
Labor (obviously)
Updated cylinder head gasket set
Updated cylinder head bolt sets
Timing belt and water pump component set (comes with tensioners and idlers)
Thermostat
Engine oil and filter
Coolant
Send cylinder heads to a machine shop to have checked for cracks, check all valves for wear, and then resurface (this part often gets overlooked when calling around)
Book an Appointment with A.B. Hadley
If you know or think your Subaru is showing signs of cylinder head gasket failure, book an appointment or give us a call! We will walk you through our diagnosis and estimate process.