How To Test For A Blown Head Gasket (2000-2010 2.0L Ford Focus)

Checking whether your 2.0L Ford Focus has a blown head gasket isn't difficult. In this tutorial, I'll walk you through four simple tests that will tell you if the head gasket has failed.

With any luck, your results will show the head gasket is fine. The good news is the first two tests take less than five minutes and require no tools at all.

The last two tests do need a couple of tools: a compression tester for the third test and a block tester for the fourth. If you don't already own them, I'll show you where you can get them. Let's get started.

APPLIES TO: This tutorial applies to the following vehicles:

• 2.0L SOHC Ford Focus: 2000, 2001, 2002, 2003, 2004.
• 2.0L DOHC Ford Focus: 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010.

Symptoms Of A Blown Head Gasket

In my experience, head gasket failures usually show up in one of two ways:

• Engine runs but overheats: The motor starts and runs, but the temp gauge climbs into the red even though nothing obvious seems wrong.
• Engine won't start: The motor cranks over but never fires up.

Below are the most common symptoms you'll run into when the head gasket lets go on a 2.0L Ford Focus:

• Overheating: The engine overheats and there's no clear reason why.
• Oil and coolant mixing: The oil looks milky —like coffee with too much cream— from coolant leaking into the crankcase.
• White exhaust smoke: Thick white smoke out of the tailpipe caused by antifreeze burning inside the cylinders.
• No-start condition: The engine cranks but refuses to start.
• Cooling system overpressure: The reservoir bottle gets over-pressurized and coolant is forced into it whenever the engine is idling or shut off.

TEST 1: Engine Oil Mixed With Coolant

This is usually the first check a shop does when you bring a vehicle in for a blown head gasket diagnosis.

It's super easy, and if the head-gasket failure is severe, you'll usually see coolant in the crankcase mixing with the oil. The oil will look like "coffee with too much creamer".

This happens because coolant and motor oil move between the block and the cylinder head through separate passages. The head gasket's job is to seal those passages, keeping coolant and oil out of the cylinders and away from each other.

When the engine overheats badly enough to warp the aluminum head or burn the gasket, that seal fails —and the two fluids mix.

Because this is one of the most common results of a blown head gasket, it's the first thing we're gonna' check:

1. 1

   Open the hood of your Focus.

2. 2

   Pull out the engine oil dipstick.

3. 3

   Check the color of the oil sticking to the dipstick.

4. 4

   You'll see one of two things:
   
   1.) The color of the oil will be a milky white color (like coffee with too much cream).
   
   2.) The color of the oil will be its normal color.

Let's take a look at what your test results mean:

CASE 1: The engine oil was a milky white color. This tells you that the coolant is mixing with the oil and that you do have a blown head gasket on your hands.

CASE 2: The engine oil was its normal color. So far so good. Let's move on to the next test: TEST 2: Coolant Shooting Out Of Radiator.

TEST 2: Coolant Shooting Out Of Radiator

As the engine runs, the combustion cycle produces several different pressures (compression, combustion, exhaust, etc.). These gases and pressures are normally sealed inside the cylinder by the head gasket, keeping them out of the cooling system.

When the head gasket fails, it can't hold them in anymore. As a result, combustion gases escape into the cooling system through the coolant passages in the head and block.

So, for our 2nd head gasket test on your 2.0L Ford Focus, we'll check to see if compression/exhaust pressure is escaping into the pressurized coolant reservoir (also called the expansion tank or degas bottle).

These are the test steps:

1. 1

   Remove the cap from the coolant expansion tank. If the coolant level is low, top it off before proceeding.
   
   IMPORTANT: Make sure the engine is completely cold before opening the coolant expansion tank. Opening it on a hot engine can spray pressurized coolant and cause severe burns.

2. 2

   Stand at a safe distance from the engine but keep the reservoir in view.

3. 3

   Have your helper crank the engine.

4. 4

   You'll see one of two results:
   
   1.) The coolant shoots out violently as soon as the engine cranks.
   
   2.) The coolant remains undisturbed.

Let's look at what the results mean:

CASE 1: The coolant shot out of the reservoir. This confirms beyond a doubt that the head gasket is blown.

CASE 2: The coolant DID NOT shoot out of the reservoir. So far, so good. In TEST 1 you confirmed the coolant isn't mixing with the engine oil. In this test you've confirmed no combustion gases are entering the reservoir.

Your next step depends on what your Ford Focus is doing:

• If your Ford Focus starts and runs but then overheats within a few minutes for no obvious reason, go to: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).
• If your Ford Focus doesn't start, the next step is to do an engine compression test. Go to: TEST 3: Engine Compression Test.

TEST 3: Engine Compression Test

Over the years I've run into a few vehicles with a blown head gasket that didn't show the "usual" signs. In those cases, the coolant wasn't mixing with the oil, and cranking the engine didn't send coolant shooting out of the reservoir.

Even so, the head gasket was blown. The common factor every time? The engine had severely overheated.

The test here involves doing a compression test to check if two side-by-side cylinders have 0 compression. I want to stress this because it's the key: both adjacent cylinders will show 0 PSI.

This happens when the gasket burns through between two cylinders, letting compression from one leak into the other and back again.

If you don't have a compression tester, this is the one I recommend: BETOOLL HW0130 8pcs Compression Tester (Amazon affiliate link).

NOTE: For a complete step-by-step on performing a compression test —and how to interpret the results— see: How To Test Engine Compression (2000-2010 2.0L Ford Focus).

These are the test steps:

1. 1

   Disable the ignition system if your Ford Focus uses a coil pack by unplugging it from its electrical connector.
   
   If your Focus is equipped with coil-on-plug ignition, you don't need to disable anything.

2. 2

   Remove all four spark plugs.

3. 3

   Thread the compression tester into the first cylinder by hand (snug only —no tools).

4. 4

   Have your helper crank the engine while you watch the gauge.

5. 5

   Once the needle stops climbing, tell your helper to stop cranking.

6. 6

   Write down the reading, then repeat the test on the remaining cylinders.

Here's how to read the results:

CASE 1: Two side-by-side cylinders both show 0 PSI. This confirms without a doubt that the head gasket is blown.

CASE 2: All cylinders show normal compression. This is the expected and correct outcome.

But (and there's always a "but") if your Focus still overheats with no clear cause, move on to the next section: TEST 4: Using A Chemical Block Tester (Combustion Leak Tester).

TEST 4: Using A Chemical Block Tester (Combustion Leak Tester)

Sometimes you're dealing with a head gasket problem that the first three tests don't catch. When that happens, the surest way to confirm it is with a chemical block test.

A combustion leak tester (block tester) is what good shops use to verify a blown head gasket. In simple terms, here's how it works:

• Pour the special test fluid (it starts out blue) into the tester (see photo above).
• Fit the tester to the pressurized coolant reservoir (expansion tank/degas bottle). You may need the coolant level a bit lower so the tool can draw air from the tank.
• Start the engine and let it idle.
• Squeeze the rubber bulb to pull reservoir air up through the fluid chambers. As the bubbles pass through, a chemical reaction can occur.
• If the blue fluid turns yellow (gasoline engines), combustion gases are getting into the cooling system. That confirms a blown head gasket, a cracked head, or a cracked block.
• If the fluid stays blue, you can rule out a blown head gasket (and a cracked head/block) based on this test.

Where do you get the fluid and tester? Most auto parts stores carry them — or you can pick up a kit here:

Frequently Asked Questions

1.) How do I know if the cylinder head is cracked?

The head has to come off and be inspected closely. If the crack is big enough, you'll be able to spot it with your eyes.

But not all cracks are obvious, which is why the smart move is to have a machine shop pressure test the head. That way you'll know for sure.

2.) Do I need to resurface the cylinder head?

YES —always have the cylinder head resurfaced before reinstalling it, especially if the engine overheated. Skipping this step is asking for trouble.

The only exception is if you (or the machine shop) check it with a straight-edge and confirm there's absolutely no warpage. Otherwise, resurfacing is a must.

3.) Do the cylinder head bolts need to be replaced?

YES —the head bolts on the 2.0L Ford Focus are torque-to-yield (stretch) bolts. They physically stretch when tightened to spec. Once stretched, they can't be reused. So the old bolts you pulled out with the head gasket need to be replaced with new ones.

4.) Should I use a "blown head gasket repair" sealer in a can?

I don't recommend it —but here's the reality.

Sealants sometimes work, but only when the head gasket leak is very small, like a minor coolant seep into a cylinder. Even then, it's hit or miss.

The bigger problem is that the sealer doesn't just stay at the head gasket —it circulates through the whole cooling system. That can eventually clog the radiator, heater core, or coolant passages, cutting down the system's ability to cool the engine.

And if you later replace the gasket, you'll have a new headache: cleaning out the hardened sealer. It can gum up everything and add more cost to the repair.

Believe me, I understand —a head gasket job isn't cheap, and even DIY it's a lot of labor. So I understand why people try a can of sealer first. But if your engine is already overheating or losing coolant quickly, odds are it won't fix it. And if it does, the fix is usually short-lived.

More 2.0L Ford Focus Diagnostic Tutorials

You can find a complete list of tutorials and wiring diagrams for the 2.0L Ford Focus in this index:

• 2.0L Ford Focus Index Of Articles.