Portable Automotive Smoke Machine is designed to find leaks in engine cavities by supplying smoke there and visual detection of its exit from the outside of the system under test. It features a convenient, easily dismantled design and simple control by one multifunction button.
The machine is made in the form of a cylinder, which has a detachable bracket for hanging to the car’s hood. An electrical cable and a plastic compressed air hose are fed to the bottom of the casing. There is also built-in backlight of 18 LEDs, designed to indicate the connection of the cable to the battery, and additional illumination of leakage points. At the top of the machine is located a multifunction button, highlighted when pressed. This button controls the activation of heating, smoke supply, and pressure control. This allows, without distracting from the search for leaks, to control the operation of the smoke generator, to take breaks during the leak test, or to apply smoke in small portions when inspecting the leak spots in detail.
When the multifunction button is pressed, the locking of the removal of the bracket is disabled, therefore it is recommended to hold the smoke generator by hand.
Preparation for work
To refill the machine with liquid from which smoke (steam) is generated, or to check its level is necessary to remove the bracket for hanging. To do this, by pressing the multifunction button, press the bracket on both sides with your fingers and pull it out. Then, pull out the button assembly together with the heating element built into it.
Fill the generator with 5…10 ml of a liquid to produce smoke (roughly to the middle of the level of the dispenser spring inside the fill chamber). It is recommended to use baby oil “Johnson’s Baby” or ATF transmission oil. One refueling is enough to hold 5…10 tests.
Checking the liquid level or refueling of the smoke machine is allowed to be performed without disconnecting the supply of compressed air and power from the battery. But, in this case, you must take precautions, and do not touch the heated internal parts of the smoke machine.
For operation of heating element of the smoke machine, the supply cable of the device must be connected to a car battery with a voltage of 12 V. The red crocodile from the cable must be connected to the “+” terminal and the black one to the “–” terminal.
Two standard car fuses rated for 10 A and 15 A are inside of the power cable. The red fuse (10 A) protects against exceeding the maximum current and short-circuit, blue (15 A) – protects against incorrect polarity of connecting the supply cable to the battery in case where the body of the smoke machine is connected to the “ground” of the car (for example, when it is suspended to the car’s hood).
Smoke machine is designed for connection to a compressed air line with a pressure of 1.5…10 Bar. For connection to the compressed air line, to the wheel nipple adapter is connected a standard quick-detachable adapter.
An adjustable throttle is installed inside of the quick-detachable adapter for the compressed air line. Turning the screw when adapter is disconnected, you can change the throttling section, and, accordingly, the amount of smoke. It is necessary to adjust the throttle to the desired smoke supply in accordance with the compressed air pressure in your system.
Also, smoke machine can operate from compressed air supplied from the car’s wheel. At the same time, no additional adjustments are required. To connect smoke machine to the air pumped into the car’s wheel, a built-in compressed air hose with adapter for the wheel nipple is used. During operation, the device consumes a small amount of compressed air with an optimum smoke output of 5…10 l/min.
In order to check the tightness of the intake manifold, it is necessary to block the inlet duct, installing, for example, a suitable piece of polyethylene film at the junction of the air duct.
Further, it is necessary to connect smoke machine output hose to the fitting on the engine intake manifold.
If there is no suitable fitting on the intake manifold, smoke can be supplied through the oil dipstick tube.
Smoke machine is controlled by pressing the multifunction button. The beginning of smoke generation and its supply to the intake manifold is controlled visually by the appearance of smoke in the output transparent hose. Smoke should appear about 3 seconds after the heater is turned on. Approximately 5 seconds after the start of smoke generation, it is recommended to temporarily remove the finger from the multifunction button. If, after that, a jet of smoke appears from the indicator hole in the center of the button and does not stop for about 3 seconds – the system under test is practically tight, and there are no leaks that affect the operation of the engine.
If there is no smoke when releasing multifunction button from the indicator hole, there are large leaks in the system. In this case, smoke can be applied until visually places of its exit appear.
During the search for small leaks, it should be borne in mind that as the smoke flows, the pressure in the intake manifold may increase. The smaller the leak, the slower the smoke moves, and the greater possibility of increasing the pressure. When the button is held with a force of 2.5…7 kg, the pressure is limited to 0.2…0.6 Bar. This pressure is recommended to search for leaks in the intake tract of engines equipped with a supercharger, since they can leak only at increased pressure. In all other cases, a lower pressure is recommended to search for leaks – approximately 0.05 Bar. The design of machine allows to limit the smoke feed pressure due to the area of the inner surface of the button-piston. An increase in the smoke feed pressure results in an increase in the reverse force of the button. When the reverse force of the button exceeds the force of pressing it, the smoke supply, heating and backlighting will automatically turn off. For additional pressure monitoring, an indicator hole located at the center of the multifunction button is used: a sign of the presence of excess pressure is the appearance of a smoke stream emerging from this hole after releasing the button.
On some engines, the bottom part of the oil dipstick tube may be located below the oil level in the crankcase. If the oil dipstick plug is not sealed, then even with a slight increase in the smoke supply pressure, the engine oil can flow up the oil dipstick tube and begin to pour over its upper edge. The level of the lower part of the oil dipstick tube in the crankcase can be determined by applying a little air to the dipstick tube with open oil filler cap. If you hear a specific sound of air bubbles outputing from the liquid, then it is located below the oil level.
To shorten the search time, it is recommended to open the oil filler cap of the engine and hold the multifunctional button of the machine until the smoke shows off from the oil filler neck. This will indicate that the entire diagnosed system is filled with smoke.
Then you must close the oil filler cap and press the multifunctional button again.
In a short time, you will see the leak points.
At the end of the diagnostics, before unpluging the smoke supply hose, we first recommend opening and closing the oil filler cap again. It should be borne in mind that not all modern crankcase ventilation systems have a non-overlapping connection to the intake manifold.
The search for significant leaks is much easier than searching for small leaks. Small leaks almost do not affect the engine operation and their search is performed considerably less often. It should be taken into account that if significant leaks are present, it is more difficult to detect minor leaks.
If leak points aren’t seen, then it is possible that the smoke escapes into the exhaust system through unclosed valves in the cylinders or through the unclosed EGR valve. In this case, it is recommended to close the exhaust pipe, inserting into it, for example, rags, but not very tightly.
Checking the ventilation system of crankcase gases by a smoke machine allows you to detect, mainly, external leaks. In order to detect internal leaks or check the operation of the crankcase ventilation system, knowledge of the device and the operating principle of this system and the corresponding qualification of the master are necessary.
When searching for faulty sealing in the fuel tank ventilation systems, it is not recommended to use air for generating smoke, since the supplied air will mix with the fuel vapors and significantly increase the danger of ignition from the slightest spark. It is recommended to supply an inert gas to the smoke machine instead of air, for example, nitrogen (smoke produced by the smoke machine is not smoke in fact; actually, it is oil vapors).
It is not recommended to start the engine with the smoke machine pluged to the intake manifold. Because of the differential pressure created in the intake manifold, the machine button can turn on itself and cause an unforeseen smoke supply.
It is not recommended to hold the multifunctional button for a long time when the power is connected and the compressed air is switched off, as this can lead to overheating of the smoke machine and its heating element.