In this article, I'm gonna' show you how to do an engine compression test on your Nissan 2.4L Altima, Pathfinder or Xterra vehicle.
An engine compression test is not hard to do (since you're only dealing with 4 cylinders) and it should take you about 30 minutes to do.
Here are the contents of this article at a quick glance:
- Important Tips And Suggestions.
- Symptoms Of Low Or No Engine Compression.
- The ‘Dry’ Engine Compression Test.
- ‘Wet’ Engine Compression Test.
- Why An Engine Compression Test?
- Which Compression Tester Should I Buy?
- Related Test Articles.
Important Tips And Suggestions
TIP 1: The compression test is done with the engine cranking, so you'll need to be careful and take all necessary safety precautions.
TIP 2: You'll need a helper to crank the engine for you, while you eye-ball the compression tester. My suggestion to your helper wait outside the vehicle till you're done setting up the test. Once the test is done, ask you helper to wait outside again.. this will help you to avoid having him or her accidentally crank the engine while you're setting up the test.
TIP 3: If the engine starts, you should perform the compression test with the engine warmed up, but not completely hot (normal operating temperature). If the engine does not start, don't worry about it.
Symptoms Of Low Or No Engine Compression
Having low or no engine compression in one cylinder on your 2.4L Altima (Frontier, or Xterra) will cause your engine to miss at idle and you'll definitely feel there's something wrong when you accelerate the vehicle.
When this happens (low or no compression on just one cylinder), you'll see one of the following Misfire Diagnostic Trouble Codes:
- P0300: Random Cylinder Misfire.
- P0301: Cylinder #1 Misfire.
- P0302: Cylinder #2 Misfire.
- P0303: Cylinder #3 Misfire.
- P0304: Cylinder #4 Misfire.
Now, a lot of times, low compression at idle, will only cause a Rough Idle Condition and it won't set a Misfire Trouble Code at all.
The next common scenario is having low or no engine compression on two engine cylinders... and your Altima (Frontier, or Xterra) won't start. It'll Crank but Not Start. This usually indicates a blown head gasket.
If a blown head gasket is a concern... take a look at this tutorial I've written: How To Troubleshoot A Blown Head Gasket (Nissan 2.4L, 2.5L).
When you have a situation where you have NO Compression on ALL 4 cylinders, you'll see:
- When you crank the engine over, it cranks very fast... and this fast cranking speed is very noticeable.
- You'll have spark (in every cylinder), so you know it's not an ignition system issue.
- The fuel injectors spray fuel.
- You can confirm this with a Noid Light test.
- Also, you can confirm this, although indirectly, by removing the spark plugs and checking to see if they are fuel soaked (fuel fouled).
- The most common causes of this scenario, are:
- Blown head gasket.
- Broken timing chain.
- Engine thru' a rod.
OK, having covered the most common scenarios of low compression and no compression, let's get testing to see if this is the case on your 2.4L Altima (Frontier, or Xterra).
The ‘Dry’ Engine Compression Test
Let's jump right into the ‘Dry’ Engine Compression Test.
Before you start, let me just say (one more time) that you'll be working around a cranking engine, so you have to be careful and stay alert at all times.
This is a pretty easy test and at the end, I'll show you how to interpret your test results. If you do find that you do have one or several engine cylinders with low compression, I recommend testing those cylinders with a ‘Wet’ compression test (and you'll find the instructions for this ‘Wet’ compression test in page 3 of this article).
Alright, let's start:
Disable the fuel system. You can easily accomplish this by disconnecting all of the four fuel injectors. Disabling the fuel system will prevent fuel from being injected into the cylinders.
The ignition distributor has to be disabled. You can easily do this by unplugging the distributor's connectors (disabling the distributor will keep the ignition coil from sparking).
Now, remove all four spark plugs. As your taking them out, be careful and don't drop any of them on the floor, or you could cause the spark plug's ceramic insulator to break, and this will cause a misfire!
Thread the engine compression gauge into the spark plug hole for the number 1 engine cylinder (this is the spark plug hole closest to the drive belt). Hand tighten the compression gauge only! Do not use any type of tool to get it tight.
OK, when the tester is set up, have a helper crank the engine on your Nissan while you observe the needle on the compression tester's gauge. Once the needle on the compression tester stops climbing, have him or her stop cranking the engine.
Record this compression reading on a piece of paper. Include the number of the cylinder this reading belongs to. Now repeat steps 1 thru' 6 on the other 4 cylinders.
Continued in the next page...