The engine power balance test, can be a great way to pinpoint, a cylinder that is underperforming.
Above all, a cylinder that is not working as well as, the other cylinders in the engine.
The engine power balance test, measures the power that a particular cylinder contributes, to the total power of the engine.
Also, doing a engine power balance test, will point you in the correct direct to make the needed repairs.
How To Do A Engine Power Balance Test
The test, uses the cylinder’s effect on the engine’s (RPM), to determine this power. So, while the engine is running, either a spark plug or primary circuit is grounded. As a result, this prevents the spark plug from firing in the cylinder, which prevents combustion in that cylinder.
So, the engine (RPM) should decrease, when the cylinder is inoperative. Next, record the drop in the (RPM), and compare it to the other cylinders. So, if all the cylinders produce the same amount of power, then all engine (RPM) drops would be the same.
But, if the drop in engine (RPM), becomes much more for that cylinder, than for the other cylinders. Then, the engine will run rough. Because, one or more cylinders, are not producing as much power as the others.
The Engine Power Balance Test, Identifies The Less Productive Cylinders
Also, if the engine has an (EGR) valve, the vacuum line must be disconnected and plugged. Changes in engine vacuum, may cause the (EGR) valve to cycle on and off. And, this can very the engine (RPM) and interfere with the readings.
The engine power balance test is quick, and easy to perform. But, the results of this test alone, do not specify, where the problem is.
So, you need to compare these results, to the results of a compression, and cylinder leakage test:
- The compression test determines, the maximum pressure in the cylinder, on the compression stroke.
- The cylinder leak down test, measures how well the cylinder seals.
Finally, by comparing the results of each test to each other, you can identify, what may be the problem.
If the results of the test show that it has:
- Good compression.
- Proper leakage.
- Good engine power balance.
Then, a leaking cylinder, would not be the cause of the imbalance. And, the fuel system of most engines is common to all cylinders. Therefore, it would not cause a power balance problem.
Other things that might cause the problem are a:
- A non-common system.
- An ignition problem, usually in the secondary.
- A vacuum leak, that does not affect all cylinders.
Mechanical failure or a defect, that might cause a failed engine power balance test can be a:
- Bent Pushrod.
- Broken Rocker Arm.
- Worn Camshaft Lobe.
- Collapsed Hydraulic Lifter.
Furthermore, all these faults do not affect the sealing of the cylinder. But, do affect the opening of the valves.
So, to determine the exact cause, you should test the ignition system.
First, an engine with good compression, good engine power balance, and excessive cylinder leakage. Is typically an evenly worn high-mileage engine. But, an engine with poor compression, proper leakage and good balance test, usually has a valve timing problem.
Conclusion
Use the combination of the results for further testing from the:
- Compression test.
- Cylinder leakage test.
So, many things can cause a weak cylinder. And, it may take some time, to locate the engines exact problem. Also, one possibility may be, a leaking head gasket. And, they make a testing fluid that can confirm this problem, by testing for the presence of hydrocarbons. Finally, as you can see doing a engine power balance test, can be very helpful.
BY DANNY BENDER
