There is some debate about the exact reason for this problem, but they're all deeply rooted in one key concept: bad design. Here are some theories:
- Subaru's single overhead camshaft design (SOHC) engine use the same badly designed cylinder heads from older engines that also had gasket problems.
- The horizontally opposed engine uses both aluminum blocks and heads, which tend to move around and create more wear.
- Voltage in the cooling system is believed to contribute to gaskets corroding and failing.
- Subaru's factory gaskets use a coating that deteriorates faster than a pile of nachos in a fraternity.
Leaking Oil and Coolant ∞
Head gasket failure in a SOHC engine is a passive leak between the coolant jacket, oil gallery and the exterior of the motor.
It typically starts with an external oil leak at the back of the cylinder head. More often that not this happens on driver's side gasket. Most owners only become aware of this when they bring their car in for routine maintenance or if they notice a drop or two of oil on the driveway.
Eventually external coolant leaks can also start to happen. Owners can start using their senses on this one. They might see engine temperature fluctuations, hear noises like engine knocks or smell the terrible fragrance of their engine eating itself alive.
“Oil leaks are bad. Coolant leaks are worse. Mixing the two can be catastrpohic. The gnarly mix will corrode gasket seams and eat away at bearings.”
If these leaks are left untreated, they will strengthen and the cause the engine to overheat ... or worse.
An Unavoidable Issue? ∞
Even following the manufacturer's recommended service intervals will do nothing to prevent this problem from happening. Once your car is north of the 75k mile mark, you're at risk.
I found out today that my Subaru has both leaking head gaskets. Being the ONLY owner of this vehicle and keeping meticulous maintenance and up keep according to the factory manufacturers guidelines, I have to fix both head gaskets at only 77K miles? This is outrageous; I could not have avoided this repair AT ALL. This should definitely be a recall given the amount of complaints on the web about this issue. — 2007 Outback owner
If you really want to avoid this problem, go with a 6-cylinder Subaru engine or use it as an excuse to get a turbo. "But honey, we need the turbo to avoid costly head gasket issues down the road."
Catching it Early ∞
While the problem can't be prevented, you can catch it early and plan for the repairs.
As your car racks up the miles, it might be a good idea to have your mechanic inspect the heads for leaks during otherwise routine maintenance. Any small leak can be monitored over time while you begin to pawn off your prized possessions to save up for the impending repair.
Repairing the Problem ∞
Replacing head gaskets is a very comprehensive and labor-intensive task. The actual gasket itself it usually pretty cheap, but the labor costs are what gets you. Why? Because to truly fix the problem the entire engine needs to be removed and that cost alone will be more than $1000.
That's why when head gaskets get repaired, your mechanic will typically recommend you get other work done at the same time. Things like replacing the water pump, timing belts and tensioners, and thermostats -- all of which is made much easier by the fact that the engine is already removed.
Yes, your bill will skyrocket (most say somewhere between $2200-$2500) but despite the wallet pain, this isn't a scam and will ultimately save you money in the long run.
Head Gasket Problem Review ∞
- If you own a Subaru with a 4-cylinder, non-turbo engine, your head gaskets will fail at some point.
- These gaskets have failed consistently for the last 25 years because of bad design or cheap materials.
- The repair will require the engine to be removed, so it's best to have other work done at the same time.
- Typical repair costs will be between $2200-$2500.