This tutorial will explain the four most common blown head gasket tests you can perform to diagnose a blown head gasket on your 2.4L Nissan Altima (or Xterra, Frontier).
You can accomplish two of the four tests within 10 minutes and without any tools at all. The other tests are done with an engine compression tester and a block tester. All four tests are explained in a step-by-step fashion.
Contents of this tutorial:
Symptoms Of A Blown Head Gasket
The most common cause of a blown head gasket is that the engine overheated due to one of the following: 1) The radiator fan or fan clutch is not working, 2) Engine has No coolant, due to a leak somewhere in the coolant system 3) Thermostat went bad and is stuck closed. The most common symptoms a blown head gasket are:
- Your car or pickup is overheating. You know it's not the fan or thermostat.
- White smoke is coming out of the tail-pipe and it smells like anti-freeze being cooked.
- The car or pickup won't start.
- You have already verified it's not an ignition system problem because you have spark coming out at all of the spark plug wires.
- You know it's not a lack of fuel, because you have verified that the fuel pump is delivering fuel to the fuel injectors.
- The engine oil is thick and tan to off-white color.
TEST 1: Coolant Mixing With Oil
There's a good chance, that you may not have to do all three tests, to find out that the head gasket on your Nissan 2.4L vehicle is blown.
So, if this first head gasket test let's you know that the gasket is blown, then you don't need to continue to the rest.
If this first one, doesn't prove that the head gasket is bad, then go on to the other one.
OK, I'll stop talking and we'll get this show on the road, this is what you need to do:
Open your Nissan's hood.
Pull the engine oil dipstick out of the engine.
Visually check the color of the oil and its viscosity (that's on the dipstick).
You'll see one of two things:
1.) The oil on the dipstick is a creamy tan to off-white color.
2.) The oil on the dipstick is its normal color and viscosity.
Take a look at the following interpretations to find out which one best fits what you have observed of the color of the oil:
CASE 1: The color of the oil is a light tan, like coffee with too much creamer. This confirms that the head gasket is blown and that it's letting coolant mix with the engine oil.
If you're wondering why the oil looks like this? The biggest and most common reason is that the engine severely overheated or was overheating (even slightly) over the course of several weeks and:
1.) The cylinder head (since it's made of aluminum) warped which caused the head gasket to burn.
2.) And a burned head gasket can not seal the oil and coolant ports in both the engine block and the cylinder head (especially with a warped cylinder head).
3.) This leads to the coolant entering the engine oil pan. As both oil and coolant mix, the resulting combination gets thick and becomes an off-white color.
CASE 2: The color of the engine oil is normal. So far so good, but you still need to continue on to the next test: TEST 2: Compression Shooting Out Of The Radiator.
Normally, when the head gasket fries in your Nissan Altima's (or Frontier, Xterra), the coolant will mix with the engine oil, but not always. This is why one or maybe two more tests are needed to make sure that the head gasket is really blown or not. The next test is to see if the engine's compression/combustion gases are escaping thru' the radiator.