A crucial multi layered metal and/or graphite composite that makes a water-tight seal between two halves of an engine, the head gasket’s job is two-fold: to seal combustion chambers that reach pressures in excess of 200 per square inch and extreme temperatures of nearly 3,000 degrees Fahrenheit; and to separate coolant passages that hold almost 20 pounds per square inch of pressure (with temperatures over 220 degrees) and oil passages that typically run 30-60 pounds per square inch. If the head gasket leaks from one passage into another even a smidgeon, it is toast and you're in need of immediate head gasket repair. The engine will soon be toast, too, if it’s run with a leaky head gasket for very long!
The most common head gasket failure: coolant improperly enters the combustion chamber. When the piston is on its down stroke it pulls in gas and air in preparation for the combustion process. With a leaky head gasket, coolant also enters the system. Then when the piston comes back up to Top Dead Center (TDC), the fuel ignites from the spark. But so does the misplaced coolant. This is what causes excessive white smoke to come from the tail pipe. When there’s an excess, the vehicle runs rough. When you have too much coolant, the engine will stop in its tracks as the result of hydro-lock. But that’s not all that can happen. This sudden stoppage could bend a connecting rod, causing internal engine failure. Also, when the piston comes to TDC, it pushes 200 lbs of pressure into the cooling system, causing it to boil over from excessive air pressure and the extreme heat from the combustion chamber.
With a blown head gasket, oil can run into the coolant system and vice versa. The mixing and sloshing of the two creates a 'chocolate milkshake'-looking effect. This is bad! The coolant in the oil system will ruin the bearings in the engine, sometimes immediately. Left unaddressed, the cost to repair or replace this kind of engine damage goes well beyond simple head gasket replacement.
Because of the extreme conditions this gasket is under every time you turn on your engine, it’s just a matter of time before it will fail.
Common failures are the result of high mileage, old age, failure to maintain the cooling system by changing your antifreeze regularly, running the engine hard, and engine or gasket design flaws. (Subaru is infamous for gasket design flaws.)
Early Warning Signs
Early warning signs that your vehicle needs head gasket repair include overheating, loss of coolant, excessive white smoke from the tail pipe, or a rough-running engine when you start the vehicle, especially if it's been sitting overnight. The rough running will generally last for just a few seconds. On engines with a severely blown head gasket, the engine will run rough all the time, coolant may spew from the radiator, and the engine may hydro-lock.
Again, a leaking head gasket will often leak engine coolant into the oil, causing a distinctive 'chocolate milk'-like appearance that you can recognize when checking or changing your oil. The oil level might be higher than normal, too.
Failed head gaskets can emit a white, sweet-smelling smoke from the tail pipe. If you suspect that your head gasket needs repair, get it in right away. Do not delay! Bring your vehicle to one of our convenient locations in North Seattle or Shoreline.
Great experience at Chuck's with a head gasket job on a 2006 Subaru. They were friendly and thorough and took the time to explain exactly why the problems occurred and what it would take to fix them. They also made sure they took care of all other maintenance items while they had the engine taken apart. Very disappointed in Subaru however. I do not expect such a major design flaw to surface at 100k miles. As with all car repairs, the proof of the skill and workmanship of the mechanics comes after several months and years of driving, but I am confident Chucks will stand by their work.
surprising based on age of car. They texted a detailed quote then called me to go over each item. No pressure on me to approve any or all the work. Because of scope of repairs, could not be completed same day. But work was done within time frame provided. One part cost slightly more than estimated only because they had to get from the dealer(again due to age of car)although they did try other options first. This was discussed before proceeding. I was very satisfied with the communication and professionalism.
Chuck's Auto Repair - Maple Leaf
5 out of 5 stars
posted 2 months ago
My daughter’s catalytic converter was stolen from her Honda CRV. Owen not only replaced this after working with our auto insurance but he and the team replaced the sway bar...
that was actually nonfunctional.
The service provided was not only excellent and timely but the team was also outstanding. They answered all our questions and were more than willing to let us know what steps needed to be taken along the way. We are happy to finally know and put out trust in an auto shop in Seattle for all our auto problems. We would recommend them to anyone who is having car problems.