How to Perform a Compression Test on the Engine in a Nissan Pathfinder
Performing a compression test on the engine in a Nissan Pathfinder is a simple way to diagnose engine trouble. When parts wear out, such as cylinder walls, piston rings and valves, the SUV loses power, burns oil or runs poorly. Tearing the engine apart to see what is happening inside is a difficult, time-consuming job, but a compression test is a quick and easy alternative.
Other People Are Reading
Instructions
-
-
1
Prepare by warming up the engine in the Nissan Pathfinder. The battery must be in good condition since it is required to rotate the engine several times during the test. Turn off the engine in the SUV once it is sufficiently warm, since running a compression test on a cold engine will give inaccurate results.
-
2
Disable the ignition system to avoid electrical shock during the compression test and remove all of the spark plugs. If the Nissan Pathfinder contains a V6 engine, there will be six spark plugs. Some 2008 models contain a V8 engine with eight spark plugs, so be sure to remove all of them.
-
-
3
Insert the compression tester into one of the spark plug holes and crank the starter to rotate the engine in the SUV. This builds compression in that cylinder so that you can record the compression number. Repeat this procedure on all of the six or eight cylinders, keeping a record of the results.
-
4
Evaluate the results by comparing these compression numbers to manufacturer specifications. If the Nissan Pathfinder contains one of the newer V8 engines, the compression ratio is 9.8:1. If the SUV has a V6 engine, the ratio is 9.7:1 for 2005-2008 models and a ratio of 10.0:1 for 2002-2004 models. Compression numbers should fall within 15 PSI of the recommended ratio.
-
5
Compare the compression numbers to each other. They should fall within 10 PSI of each other. If any of the cylinders produces a low compression number, add a capful of motor oil and perform the compression test on that cylinder again. If this causes the number to increase, the piston rings or cylinder walls need repair. If the number remains unchanged, the valves or valve seats are the problem.
-
1
Tips & Warnings
When performing a compression test on models older than 2002, check the vehicle manual for the recommended compression ratio.
