Cylinder Head Gaskets
What is a cylinder head gasket?
Conventional gasoline and diesel engines are made of two major parts: the engine block, and cylinder head. The block and cylinder head are often made of different materials. In order to seal them together, a cylinder head gasket (often called just the “head gasket”) is installed between them.
The head gasket is very flat, and usually made of metal coated in other materials. Most modern engines use a multi-layered steel (MLS) gasket design. The gasket has many holes in it: a large hole for each engine cylinder, and smaller ones for the cylinder head bolts; oil passages; and coolant passages.
Leaking cylinder head gaskets:
A cylinder head gasket that is leaking is sometimes referred to as a “blown head gasket”. It’s possible for a cylinder head gasket to leak in several different ways:
Signs and symptoms of a leaking cylinder head gasket:
Confirming the existence of a head gasket leak usually involves specialized testing by a professional, and can sometimes require disassembly of the engine. A cylinder head gasket can also leak in many different ways, exhibiting many different symptoms. The most common symptoms we see that may indicate a head gasket failure are:
- Air bubbling in the radiator, which doesn’t seem to go away no matter how long the system is bled for.
- The vehicle violently expells coolant; blowing it out around the radiator cap or coolant reservoir.
- The cooling system shows signs of excess pressure build-up, such as a cracked radiator side tank or blown hose.
- The engine overheats very quickly, such as within a couple minutes of driving from a cold start.
- White smoke from the exhaust.
- There is coolant in the engine oil, or engine oil in the coolant.
How to tell if your cylinder gasket is leaking:
If we suspect a cylinder head gasket is leaking into the cooling system, there are several tests we can do to confirm this non-invasively, without having to take your engine apart:
- Performing a combustion leak test to detect byproducts of fuel combustion (carbon dioxide) in the coolant.
- Pressurizing the cooling system with a cooling system pressure tester and then using a borescope (tiny camera) installed through the spark plug hole to look for coolant leaking into a cylinder.
- Using an oscilloscope and a pressure transducer (super sensitive electronic pressure sensor) to detect tiny spikes in the cooling system pressure when a specific cylinder fires.
In addition to these techniques, our experienced technicians have other ways to accurately diagnose a head gasket issue; and fix it too, of course!
Replacing cylinder head gaskets:
Replacing a blown head gasket is a very labour-intensive job that involves disassembling the engine fairly deeply, since the cylinder head must be removed as part of the repair. With overhead cam engines, this means the timing chains or timing belt must also be removed. During the repair, cleanliness is very important as the engine will be open to the elements. We do not consider a head gasket replacement to be a do-it yourself repair that most drivers should undertake on their own.
For the best quality cylinder head gasket repair in Airdrie, look no further than My Garage! Our skilled, hourly-paid technicians will take the time to do the little things right; ensuring you are receiving the best possible repair for your money. A poorly installed head gasket can start leaking again fairly quickly, while a proper repair will usually last for the life of the vehicle. Speaking of repairs that last, we’ll back your cylinder head repair with the best parts and labour warranty in Airdrie!
Doing the job right: Surface prep is key!
A properly-performed cylinder head gasket replacement involves a lot of time spent cleaning parts. Today’s MLS head gaskets depend on a near-perfect sealing surface on the cylinder head and block in order to seal. These surfaces must be cleaned meticulously and carefully, in order to ensure that we leave no old gasket material behind, but without creating any scratches or low spots in the surface.
The quality of this surface preparation is a major factor in how long the repair lasts, and it’s where you’ll see the biggest difference between the workmanship of a caring technician, or a technician in a rush.
We also use a machinist’s straight edge to measure the engine block and cylinder head surfaces for flatness. If these surfaces aren’t flat enough (or are “warped”), common after an engine has overheated badly, then we send the parts to our machine shop for resurfacing. Today’s head gaskets require a super flat surface, so this helps ensure that they will seal for years to come.
Doing the job right: Replace the cylinder head bolts!
Your cylinder head is secured to your engine block with large high-strength bolts. Most vehicles’ head bolts are a torque-to-yield design, which means they actually stretch and elongate as they are tightened on installation. This increases the fatigue life of the bolts and allows for better clamping force on the cylinder head. Unfortunately, this also means these bolts must be replaced every time they are removed. A torque-to-yield bolt that is re-used won’t provide the correct clampload on your cylinder head (which can lead to another head gasket leak), and it can even break!
What about “mechanic in a bottle”?
Due to the high cost of a cylinder head replacement, some drivers may be tempted to try a “stop leak” product in their cooling system. Our advice is not to do this; and it’s not because we want your money! While some of these products have decent success plugging up a leak in a stationary gasket like a water pump gasket, they usually don’t work on cylinder heads due to the high pressures involved. And when they do work, there’s a cost: Most of these products degrade the quality of your coolant, and can plug up system parts like your radiator or heater core.
Preventing cylinder head gasket failure?
Is there anything you can do to prevent a head gasket leak? Most of the time, the answer is no. Cylinder head gaskets can fail on even the most well-maintained engines. In engines that use a cast iron block with an aluminum cylinder head, the gasket is almost a wearable item, as it’s constantly being rubbed back and forth as these parts heat up and expand at different rates. That being said, there are a few things you can do to prolong the life of your head gaskets:
- Flush your engine coolant regularly, as specified in your vehicle’s maintenance schedule, which reduces corrosion inside the cooling system.
- Keep an eye on your temperature gauge, and shut the engine off it the gauge rises above the 3/4 point. Overheating is the leading cause of head gasket failure.
- Diesel owners: Avoid the use of “programmers” or “tuners” that increase horsepower, as these drastically increase cylinder pressure. (But that’s no fun; we know…)
Replacing cylinder head gaskets in Airdrie:
As with any other major engine repair, a head gasket replacement involves many important steps, and a lot of little things. While any experienced mechanic will be able to replace the gaskets and make the engine run again, it’s the proper execution of these little things that will make a difference in the long term: not only with how long the repair lasts, but how the rest of your vehicle performs as well.
These little things include:
- Painstakingly cleaning the block surfaces with gasket remover and a razor blade instead of using quicker methods like abrasive discs or sandpaper. These abrasives all shed gritty material into the engine, which causes wear on the internal parts. No matter what anyone tells you, you will NOT be able to flush them all out, and they WILL cause excess engine wear.
- Cleaning every bolt hole in the engine block with a thread chaser, so the head bolts torque down properly and evenly.
- Mixing the new coolant with distilled water – not tap water – to prevent future corrosion of the cooling system.
- And this list goes on!
A technician who just cares more will always do a better quality job. If you suspect your vehicle may have a head gasket issue, or if you’d like us to provide an estimate for the best quality head gasket replacement in Airdrie, please get in touch with us!