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8

I've posted this graphic before, but I think it's pertinent here as well: This is an image of a graph which Carroll Smith put in his book, Engineer to Win. In the book, one of the sections talks about metal fatigue. In this specific graph, he's talking about how stress affects any given metal part: how much will a part take before it fails. The graph ...


7

A simple test that you can perform in your own driveway is: For each corner of the car, push down hard several times (the car should be bouncing visibly up and down) When pushed down, release and watch The car should bounce upwards (above the normal resting point) and then immediately settle at the resting point. Additional bouncing indicates worn or ...


7

Water in fuel is easy to figure out. Put a sample (say 5 to 10 ounces) of the fuel into a clear glass container. Let it sit. If it separates into two layers, you have water in the fuel. Shown: an obviously contrived example of gasoline (10% ethanol) with approximately 2 ounces of water added - water has visibly sunk to the bottom of the jar.


6

The federal test procedures for vehicle emission certification(FTP) is run on a dynamometer. It starts with the vehicle at an exact temperature and barometric pressure and humidity. It is run in a lab that has carefully controlled exact air conditions that are maintained throughout the test. The vehicle is kept is stored at the test temperature for hours ...


5

In general, the max speed in the manual is a guide to tell you how fast it's capable of going. It's likely lower than what it's actually capable of since most buyers won't file suit if a maker under rates a car. There is always a little margin in that so I would not be concerned if you drove a bit faster than the max in the manual. I wouldn't make a habit of ...


5

Take a small propane tank, hook up a hose to it and open the valve slightly. Start following the vacuum lines until you hear the idle go up; that's where your vacuum leak is. The reason that works is that vacuum leaks are places where the vacuum system is open and drawing in air unmetered, causing the system to have a different fuel/air mixture than the ...


4

Yes it can. The reason is, these are two different tests, done differently, reading different things. To understand this, you need to understand how the tool works for each test. For the compression test, the test apparatus captures and holds the compression as it builds through several, but counted revolutions of the crankshaft. You will get so much ...


4

Compression test is more to test if there is a problem. If your compression is low, it could be a number of different issues. You can test the rings by adding oil to the cylinder and see if the compression is higher. Other than rings it can be difficult to determine the source of the issue. A leakdown test will tell you where the problem is. By watching ...


3

In my home state of Colorado, we are required to get emissions tests on our vehicles every two years (after they are a certain number of years old). They way they do this is they place the car on a dynamometer (like a treadmill), put the car in gear, and bring the wheels up to a certain speed. They have a fan placed in front of the car to help cool it down ...


3

A cylinder leak-down tester is a completely different animal than a combustion leak detection kit and has a completely different job. While the combustion leak detector checks for carbon-dioxide (CO₂) in the radiator. The cylinder leak-down tester kit hooks up to to your cylinder through the spark plug hole on one end and to your compressor on the other. You ...


3

I do it until the gauge doesn't go up anymore. I am not aware of a specific number of times that it needs to be done. That usually takes 6 or 7 times, but I have never actually counted.


2

Smoke, propane, stethoscope, and carb cleaner all work well. The last option is highly flammable and much more dangerous than propane because it sits and accumulates on the engine. It doesn't evaporate all that quickly, either. It's a very effective way to check a particular spot, to see if your hunch is right, but it's essential that you have a good fire ...


2

One pump; one pump only. Which test we perform determines the procedure used. Three procedures are described and each test has a different purpose. But keep in mind when the engine is running it only gets one pump per cycle. Running compression test: A decent way to estimate volumetric efficiency (VE). This is not technically a compression test. Install ...


2

The best (read: easiest) method to check this is doing it on vehicle. In that case, you put a fuel pressure gauge on the engine at the Schraeder valve (if so equipped) and check the fuel pressure at idle and ensure you have the proper pressure. Then pull the vacuum line to and check the pressure again, which should have changed (it should go up between 5-7 ...


1

The max speed a vehicle is rated for usually depends on the speed rating of the tires equipped by the OEM. The vehicle can move faster, but the tires are not rated to go faster.


1

I would test with a test light, not a circuit tester. A test light uses the car's battery, a circuit tester has its own battery and basically test for connectivity. When you look at the fuses, one side will be input and the other side output. If the fuse is good, you will have voltage at both sides, if the fuse is blown, you will only have voltage at the ...


1

I would say that if the overflow tank only has a small hose from the over pressure nipple on radiator right under cap then that is normal and you should put the tester right on the radiator cap mouth, as the overflow isn't a reservoir and won't be getting circulation from coolant system until the cap is over pressurized. As opposed to a reservoir or ...


1

It sounds like the mechanic is citing the maintenance schedule rather than a particular symptom. 74K miles is a good long way for a set of shocks and, while it's great that you aren't currently worried about their state, the vehicle will begin to suffer as they eventually fail. Here's a previous question that describes some of the rebounding that will ...


1

Smoke and propane both work well. Another option is a rubber hose stethoscope. This isolates the noise to the end of the hose, and will make a vacuum leak hiss fairly loudly. If you have a stethoscope with the metal rod that you use for putting on the engine block, just yank the rod part out of the hose and viola! You have a new tool. You may be able to ...



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