Doing an engine compression test on your 2.0L Dodge Stratus (Plymouth Breeze) isn't difficult! Especially since the spark plugs are easy to get to. This guide will walk you through the engine compression test steps and, more importantly, help you make sense of your compression readings.
Whether your the engine compression problem is causing an engine cylinder misfire or an engine no-start problem, this tutorial has got you covered.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar La Compresión Del Motor (1995-2000 2.0L Dodge Stratus, Plymouth Breeze) (at: autotecnico-online.com).
APPLIES TO: Applies to the following vehicles:
- 2.0L Dodge Stratus: 1995, 1996, 1997, 1998, 1999, 2000.
- 2.0L Plymouth Breeze: 1996, 1997, 1998, 1999, 2000.
Tools You'll Need:
- Compression gauge tester
- Engine oil
- A helper
- Pen and paper
Important Tips And Suggestions
TIP 1: If the engine in your Stratus (Breeze) starts and runs, it's best to do the compression test with a slightly warmed up engine as this will increase the accuracy of your compression test results.
It's important to note that the engine should not be hot, so if it has been running for any length of time, let it cool down completely before beginning to avoid the risk of stripping the spark plug hole threads.
If the engine doesn't start then don't worry about this, since you'll still be able to get a compression test result you can use.
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: The compression test is conducted while the engine is cranking. Exercise caution around moving parts to avoid injury. Always wear protective gloves and eyewear, and keep hands and tools away from belts and fan blades.
Symptoms Of Low Or No Engine Compression
An engine suffering from engine compression problems will usually have one of two problems. One, it won't start. Two, it'll run rough or have one or more misfiring cylinders.
- Hard Starting: If the engine doesn't have enough compression, it'll have difficulty igniting the fuel-air mixture, making the engine hard to start.
- Misfire: Insufficient or uneven compression can lead to an engine misfire, where one or more cylinders aren't contributing to the engine's power. You'll see one or more of the following misfire trouble codes registered in the computer's memory.
- P0300: Random Cylinder Misfire.
- P0301: Cylinder #1 Misfire.
- P0302: Cylinder #2 Misfire.
- P0303: Cylinder #3 Misfire.
- P0304: Cylinder #4 Misfire.
- Rough Idle: When there's a lack of compression in one or more cylinders, it can cause the engine to run unevenly at idle. This might make the vehicle shake or vibrate. It generally improves as you rev the engine.
- Loss of Power: Reduced compression often leads to a significant loss in engine power and efficiency. Your car might not accelerate as quickly as it should.
- Poor Fuel Economy: Because the engine isn't running efficiently, you may notice that you're getting fewer miles per gallon.
- Increased Emissions: Lower compression can lead to incomplete combustion, releasing more pollutants than usual.
- Engine Noise: A "knocking" sound can sometimes be heard, especially when the vehicle is idling.
- Warning Lights: The "Check Engine" light or other warning lights on your dashboard might illuminate.
- Smoky Exhaust: You may notice blue smoke coming out of the exhaust pipe, which is a sign of engine oil burning in the cylinder(s).
- Engine doesn't start: This usually occurs when most of the engine cylinders have very low to zero compression.
- Engine cranks faster than normal: When you crank the engine over, it cranks very fast and this fast cranking speed is very noticeable.
Which Compression Tester Should I Buy?
There are lot of engine compression testers to choose from and many places to buy them. I'm gonna' make two recommendations to you:
1) Which one to buy: The engine compression tester that I have always used is the Actron CP7827 Compression Tester Kit. My only complaint about this engine compression tester is that it does not come with a case to store it in.
Engine Compression Gauge Testers
2) Where to buy: You can buy an engine compression tester just about anywhere, but you'll end up paying more for it (especially at your local auto parts store). The above links will help you comparison shop. I think you'll agree it's the better way to save money on the compression tester!
TEST 1: Dry Engine Compression Test
You'll need to remove the spark plugs to perform the engine compression test on your Stratus (Breeze). As you remove them, check each one for visible signs of wear and tear, or indications of oil burning in the cylinder.
Also, take note if the spark plug tubes are full of engine oil, which could be a sign of leaking valve cover tube seals.
If any of these issues are present, you'll need to investigate further, as they could be the cause of the cylinder misfire or engine no-start problem you're trying to diagnose.
OK, let's get started:
Disconnect all 4 fuel injectors from their electrical connectors.
This is to prevent the fuel injectors from injecting fuel into the engine cylinders.
Disconnect the ignition coil pack from its electrical connector.
It's important that, while you're doing the test, no spark is fired from the spark plug wires. You can easily accomplish this by disconnecting the ignition coil pack.
Remove all four spark plugs.
CAUTION: Never remove spark plugs from a hot engine to avoid the risk of stripping the threads in the aluminum cylinder head. Always allow the engine to cool down completely before proceeding with spark plug removal.
Take care not to drop any of them, since dropping them can damage them and cause a misfire condition later.
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).
NOTE: Hand tighten the compression gauge only! Do not use any type of tool to get it tight.
Have your helper crank the engine.
Now the engine will not start (of course), but the idea is to crank the engine long enough to have the compression tester gauge's needle stop climbing. This usually takes about 10 seconds of cranking.
When the needle stops moving (as the engine is being cranked), have your helper stop cranking the engine.
Write down the compression reading, along with the cylinder's number, on a piece of paper.
Repeat steps 4 thru' 7 on the remaining cylinders.
Now, let's take a look at what your test results mean:
CASE 1: Your compression tester recorded NO compression on all cylinders. This isn't good and tells you that you have one of the following problems:
- Broken timing belt.
- Blown head gasket.
- Engine threw a rod.
CASE 2: Your compression tester recorded low or no compression on one or two cylinders. The next step is to interpret those numbers (compression numbers) you obtained from the tests. Go to: Interpreting The Results Of The Engine Compression Test.