How To Check Head Gasket Yourself? – Stepwise Guide

Checking your head gasket for signs of failure is an essential part of engine maintenance that anyone can perform themselves with some basic tools and mechanical know-how.

To thoroughly inspect your head gasket, you will need to start by looking for external coolant or oil leaks in the engine bay. Next, you can confirm leaks by conducting pressure testing on the cooling system. For a more comprehensive internal check, perform a cylinder leak-down test to detect compression issues. Finally, if possible, directly inspect the physical condition of the head gasket after removing the cylinder head.

This article provides a step-by-step guide to checking your head gasket in each of these critical areas – inspecting for external leaks, pressure testing, leak-down testing, and physical inspection. Following these key steps will allow you to fully assess if your head gasket needs replacement.

Step 01: Inspect the Engine Bay for Signs of a Leak

The first signs of a faulty head gasket usually appear as leaks in the engine bay. Here’s what you need to look for:

• Carefully inspect around the cylinder head and corners where the head gasket is located. Look for any droplets, drips, or puddles of coolant or oil. Coolant leaks are often green, yellow, or orange while oil leaks will be dark and greasy.
• Check the oil filler cap and dipstick for a milky, frothy residue. This happens when coolant mixes with oil, creating an emulsion.
• Start the engine and let it warm up. Watch the exhaust – white smoke or sweet-smelling exhaust can indicate coolant is leaking into the combustion chamber.

Slow seepage around the head gasket may not be visible at first, so also look for corrosion or stain marks around the gasket surface. Catch leaks early before they become more severe.

Step 02: Perform a Pressure Test on the Cooling System

Confirm coolant leaks by performing a pressure test on the cooling system:

• Obtain a cooling system pressure tester, either hand-powered or electric. Ensure the engine is completely cool before connecting it.
• Follow instructions to pressurize the system to the vehicle’s recommended pressure (often 15-17 PSI).
• Observe the pressure gauge – a rapid drop in pressure indicates an external leak. Mark any areas where you see coolant escaping.
• Let the engine completely cool again before relieving pressure and disconnecting the tester.

This test can help identify the general location of any external coolant leaks, including from the head gasket.

Step 03: Perform a Leak-Down Test on the Engine

While a pressure test finds external leaks, a leak-down test indicates if the head gasket is blown internally:

• Connect an air compressor to the cylinder head opening. With the piston at top dead center, apply around 80-100 PSI of pressure.
• Listen for air hissing from the oil filler cap, radiator, and exhaust. Measure the rate of pressure drop.
• A small amount of leakage is normal, but a sharp pressure drop over 25% indicates a bad head gasket or warped cylinder head surface.
• Repeat test for each cylinder – a problem isolated to one cylinder points to a localized head gasket failure.

This test confirms if coolant is leaking into the combustion chambers or engine oil, signature of a blown head gasket.

Step 04: Inspect the Head Gasket Itself

For complete inspection, you need to remove the cylinder head:

• With the head removed, examine the head gasket surface for any cracks, damage or corrosion. Look for signs of overheating like burn marks.
• Use a feeler gauge to measure the thickness across the entire head gasket. Compared to specifications – any readings below minimum thickness mean it needs replacement.
• Check that head gasket openings align perfectly with cylinder bores. Misalignment can cause leaks.
• Ensure proper installation by cleaning and resurfacing the head and block mating surfaces. Use torque specifications for your vehicle when reinstalling.

Thorough inspection of the head gasket itself will confirm if it needs to be replaced, and proper installation helps prevent premature failure.

How do I know if my head gasket is bad?

You can suspect a bad head gasket if you notice any of the following common symptoms: coolant leaks around the cylinder head that leave green, orange or white deposits; overheating of the engine due to disruption of proper cooling; white exhaust smoke caused by coolant burning in the combustion chamber; milky engine oil from coolant mixing; low coolant levels without visible external leaks; sudden loss of engine power from compression loss due to gas leakage. If you observe any of these signs, it likely indicates failure of the head gasket. It is advisable to diagnose with pressure testing and inspection of the head gasket itself to definitively confirm whether or not it needs replacement.

What are the first signs of a blown head gasket?

The first indications that a head gasket is blown or failing are usually: visible coolant leaks around the cylinder head, particularly green or orange staining from seepage; engine overheating or inability to control operating temperature due to coolant loss; white exhaust smoke as coolant leaks into the combustion chamber; bubbles in the radiator and overflow tank from combustion gases entering the system; milky oil residue on the fill cap and dipstick from coolant mixing with oil. Catching these early warning signs and having your vehicle professionally inspected can help avoid extensive engine damage. If you notice any of these symptoms, have your vehicle checked right away to allow early diagnosis of a blown head gasket.