Smoke ‘em if you got ‘em

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tool chest and shop

Maximizing your smoke machine

Smoke ’em if you got ’em

Compiled by Mike Mavrigian for inspecting EVAP systems, from a safety 5. Close any system vents. 6. Continue to f ll the system until the f ow meter (or indicator) shows that the system is full. 7. Visually inspect for smoke leakage (if needed, use the kit’s LED lamp to check for leaking vapor; or the kit’s UV lamp to check for dye if used).

EVAP test: Most smoke machines are designed to be used either with the shop’s compressed air supply or with an inert gas (C02 or nitrogen). Many automakstandpoint, since a spark or heat source

Asmoke machine can be used in virtucould potentially ignite fuel vapors when ally any low-pressure vehicle system mixed with air. Small CO2 cartridges are for the purpose of locating leaks, available (with preset regulator) for easy including EVAP, intake/induction system, connection to the smoke machine’s supply. oil, EGR, engine vacuum, exhaust, coolant Smoke machine units also are available with (radiator, water pump, hoses, etc.), HVAC, a built-in air compressor, eliminating the a variety of gasketed areas, engine blocks, need for an external supply connection. worn throttle shafts, diaphragms, intercool1. Perform tests with the engine off. er, turbocharger, idle motors and solenoids, 2. The vent valve is normally open with the under-dash leaks and even vehicle body engine off in OBD II EVAP systems. Use wind/water leaks. a scan tool to close the EVAP system for Basic leak testing 3. Connect the smoke machine’s power 1. Locate the system port (system to be cables (red clip to battery positive and tested). black clip to a good ground, as far away 2. Install the appropriate port adapter from from the battery as possible). the smoke machine’s kit. 4. Connect the charge source (if using shop 3. Attach the adapter to the vapor supply air, adjust pressure according to the hose. machine’s instructions). 4. Activate the smoke machine (turn on). 5. Verify that the vehicle’s fuel level is

leak tests. ers recommend the use of an Today’s smoke machines are incredibly compact, easy to use inert (non-combustible) gas and offer a wide variety of system tests.

Circle 116 on Reader Service Card

below the base of the fuel tank neck. avoid the smoke from being blown around, 6. Locate the EVAP service port (green cap). which can make locating a leak diff cult.

Remove the Schrader valve from the EVAP • Remove the fuel cap. This allows the service port (this features a left-hand system to be f lled with smoke. Fill the thread, so turn clockwise to remove). system with smoke. After a solid stream of 7. Connect the machine’s service port smoke exits the fuel tank neck, reinstall adapter to the EVAP service port and conthe fuel cap. Now the solenoid will cycle on nect the smoke machine hose. and off as pressure increases. 8. Since a common cause of EVAP DTCs is a • In order to check for intermittent leaks, faulty or improperly installed fuel cap, wiggle EVAP system components (hoses don’t disturb the cap at this point. If and connections) while watching the f ow the f rst test fails, then make sure that meter. If an intermittent leak is found the cap is installed properly and re-test. while wiggling, the f ow meter rises.

This will rule out the cap if the problem Body wind/water leaks: Set the vehicle’s lies elsewhere. Activate the leak test and climate control to “fresh air” (not “recircuobserve the f ow gauge. Allow a few minlate”) and adjust the blower to full speed. utes for the gauge to settle. This creates positive cabin pressure. Connect the smoke machine’s hose to a

EVAP test tips: diffuser. From outside of the vehicle, direct the smoke vapor along seal areas (door • NOTE: In order to pressurize the system gaps, windshield trim/gaskets, window fa ster, press the smoke button and allow seals, etc.), with the hose placed about the smoke to f ll the system until you hear two to three inches away from the inspecthe solenoid cycling, then press LEAK to tion path. If you note a disturbance in the perform the test. smoke (smoke blowing back at you), this • Perform testing indoors where the ambiindicates the location of a cabin leak. ent air is stable (avoid wind or fans), to Smoke machines that feature a f ow meter aids in determining if a leak exists (and the extent of the leak). If the f ow meter indicates f ow after the system is f lled, this indicates the presence of a leak (the higher the ball is in the f ow meter, the larger the leak). If no f ow is shown on the meter, this indicates that no leak is present. Vacuum leaks: After choosing the appropriatesize cap plug from the smoke machine kit, f rst f ll the system with smoke before you seal the system with the cap plug. If you’re checking for intake vacuum, try to seal the intake as close to the air inlet as possible (especially important Shop air is adequate for the majority of tests, while inert gas if the engine is equipped (nitrogen, CO2) is recommended for many EVAP system tests. with mass airf ow sensors

and other ducting). Consider sealing the engine’s air f lter by removing the f lter, wrapping it in plastic and reinstalling the f lter into its housing; or stretch a latex glove around the air passage and secure it with a large rubber band. Also, plug the exhaust tip (using the kit’s exhaust cone and plug the cone’s hose). An additional tip: Manually rotate the crankshaft so that intake and exhaust valves on the same cylinder are not open.

Select an accessible engine vacuum line and insert the smoke machine’s tapered nozzle (using the brake power booster supply hose is often a good choice to introduce smoke into the intake manifold, but if you choose the booster hose, make sure that you don’t place the booster’s check valve in between the smoke and the manifold).

Charge the system with smoke for about one minute and inspect for smoke leaks (or use a UV light to check for smoke dye).

EGR leaks: Leaks at the EGR valve may be detected during a vacuum leak test. If you observe smoke exiting from the valve’s seat, gasket or diaphragm, disconnect the EGR’s vacuum hose/line and push smoke directly into the EGR valve. This will help to determine if the valve seat or diaphragm is leaking. If you suspect that the EGR ports are clogged (common problem), you can remove the EGR valve (exposing the ports) and introduce smoke through the exhaust pipe (no or little smoke indicates plugged ports).

In order to test the EGR pintle shaft,

When initially testing an EVAP system, don’t disturb the fuel cap at f rst, since an improperly installed or faulty cap may be the cause of the problem. After the initial smoke check, then remove the cap and re-test. This will isolate the cap as pass/fail. the engine must be off, and don’t cap off any part of the engine. Introduce smoke through a direct manifold vacuum source (the power booster hose for example). Turn on the smoke machine tester and observe the EGR. If a noticeable amount of smoke exits the valve, cap off the intake and plug the exhaust pipe tip. Introduce smoke. A small amount of smoke indicates an acceptable EGR valve.

Brake booster leaks: Disconnect the booster’s vacuum supply hose and introduce smoke directly into the booster (eliminate the check valve for this test). Check for smoke exiting the booster canister (crimped areas, etc.), and check underdash for smoke exiting through the rear of the booster (don’t depress the brake pedal during this test).

Engine oil seal/gasket leaks: Remove the engine’s oil dipstick. Connect a

Smoke traces are easily spotted in accessible areas where visibility isn’t hindered.

For hard-to-reach or compact/busy areas, an inspection light (LED or UV) can aid in detecting the exact location of a leak.

snug-f tting section of hose over the dipstick tube and insert the smoke machine’s hose nozzle into the hose. Plug the PCV, air breather and air intake. Temporarily remove the oil f ll cap. Pump smoke into the crankcase until you see smoke exiting from the oil f ll port, and reinstall the oil f ll cap. Continue introducing smoke through the dipstick tube. Inspect the engine for leaks, looking for smoke, dripping or bubbling oil. To f nd a coolant leak using a smoke machine it’s best to f rst drain the coolant from the system, then pump smoke into the radiator.

Turbocharger/intercooler leaks: With the engine off, connect the smoke machine to the engine’s intake system, introducing smoke into the “cold” side of the turbocharger. Once charged with smoke, inspect the cold side of the turbo, the intercooler, ductwork, and the wastegate for leaks. Next, pump smoke into the exhaust pipe tip (using the cone adapter) and check for smoke exiting the “hot” side of the system (exhaust piping, exhaust manifold and the hot side of the turbo).

Exhaust leaks: With the vehicle raised on a lift and with the engine off, wait until the exhaust system is cold (due to thermal expansion, leaks will be easier to f nd on a cold system). Seal off the air intake, and adjust crankshaft position to avoid having intake and exhaust valves open on the same cylinder. Introduce smoke into the tailpipe tip (using the kit’s cone adapter). If you’re dealing with a dual exhaust, use a cone (and T-hose) for each pipe tip. Inspect for smoke exiting at any leak/poor exhaust sealing areas.

Underdash vacuum leaks: Connect the smoke machine’s supply nozzle to a main vacuum circuit that feeds through the f rewall. Activate the leak test to introduce air into the system while observing the machine’s f ow gauge. If the f ow gauge shows zero, the system has no leaks (at this point). Continue to introduce air into the system while testing each climate control setting while observing the f ow meter. If the gauge rises, a leak exists. If you suspect a leak, introduce smoke into the system (at the position on the climate control where you suspect the leak to occur). Use a light to help determine the location of the leak.

Pre-testing replacement components: It shouldn’t happen, but it does... sometimes we run into a replacement component that’s faulty, only to make the discovery after installation. A smoke machine can be used to test certain components prior to installation. In order to test components such as radiators, oil coolers or water pumps, simply plug one end and (using the correct adapter) pump smoke into the opposite end.

Smoke machine applications

Funny, but in a strange way, probably the most overlooked application is that of a general leak test. Using hand vacuum/pressure pumps, it is possible to check component level integrity, but it is diff cult or even sometimes impossible to generate enough

Example of easily visible signs of leakage.

volume to provide reliable test results on larger pieces or complete systems where a large volume of air is to be displaced.

Testing the entire system is made possible with the use of a smoke machine because of the measurable volume of smoke and/ or test gas (air, nitrogen, or other inert gas) f owing from the machine. Quite often, leaks are exposed that were not even suspected because they were not associated with any particular driveability symptom or customer complaint at that time. Get in the habit of using your smoke machine for problem diagnosis and general testing. • Example Ñ Crankcase

Here is an example where a slight oil leak can be seen on an OHC four cylinder engine. At f rst glance, it appears that the valve cover gasket is leaking. Introducing smoke through the dipstick tube into the crankcase revealed something that wasn’t expected. Smoke was escaping from the timing belt cover which indicated that something else was leaking; likely the crankshaft and/or camshaft seal. It turns out that this vehicle was nearing the mileage interval for the timing belt to be replaced, so the leaky seals were easily conf rmed and repaired when the timing belt job was performed. The seals, valve cover gasket, and timing belt replacement was the proper repair to be performed, and was easily caught with a quick smoke test of the crankcase.

It is easy to see how f nding this unexpected leak led to the discussion of a much larger job. One thing led to another and it turned out the timing belt was also due for replacement. Many shops today have in place inspection programs using quick, systematic procedures (such as this example with a smoke machine) to provide better service to their customers. And at the same time, keeping their schedule (and bays) full with productive repair business. • Example Ñ Induction system

Introducing smoke through the air intake is a quick way to f nd un-metered air leaks throughout the induction system. One way is to use the tapered cone adapter that comes with your machine to connect into the system by simply opening the intake

Notice the escaping smoke. Look close and you’ll see that someone is using a zip tie rather than the OE clamp.

air system and inserting the cone. Notice the escaping smoke in the picture above? Look close and you may see that someone is using a zip tie (the black tab is sticking straight up) rather than the proper clamp to secure that end of the hose. • Example Ñ Exhaust system

Exhaust systems need to be inspected, as well. Test with the system cool so heat expansion is not a factor in the case of a small leak, and the catalytic converter will not impact the quality or quantity of your smoke.

Catalytic converter leak on back side.

As you can see by the f ex tube leak, there are smoke machines that have UV dye solution contained in the smoke. This allows the dye to be carried airborne and Tapered cone in tailpipe. deposited at the exact point of leakage. It is revealed by using a UV light and is very handy when you can see the smoke, but the leak is hidden until further disassembly allows it to be revealed. Just hit it with the UV light and look for the dye!

These are but a few examples of general purpose leak detection; there are many other applications that will likely cross your path. Let your imagination be your guide and use this technology whenever you need to verify a system or component is sealed. ●

For more information, including a detailed look at f ow meters and compound pressure gauges, see www.autoserviceprofessional.com. Smoke machine sources Bosch — SMT 300 www.boschdiagnostics.com

Motorvac — Cool Smoke www.motorvac.com

OTC — LeakTamer www.otctools.com

Redline — Smoke Pro www.redlinedetection.com

Smoke Wizard www.smokewizard.com

Star Envirotech www.starenvirotech.com/smoke.html

Vacutec — Leakf nder Series www.vacutec.com