{"id":6304,"date":"2020-11-02T23:07:26","date_gmt":"2020-11-03T07:07:26","guid":{"rendered":"https:\/\/mitchell11.wpenginepowered.com\/blog\/shopconnection\/so-your-truck-needs-a-smoke-test\/"},"modified":"2025-05-29T08:45:37","modified_gmt":"2025-05-29T15:45:37","slug":"so-your-truck-needs-a-smoke-test","status":"publish","type":"shopconnection","link":"https:\/\/mitchell1.com\/shopconnection\/so-your-truck-needs-a-smoke-test\/","title":{"rendered":"So Your Truck Needs a Smoke Test?"},"content":{"rendered":"

When all systems are operating properly, today\u2019s newer diesel engines do not produce smoke like older diesel engines used to. The days of \u201crolling coal\u201d are over, and this is a great thing for our health and the environment, too.<\/p>\n

Here in California, where the Mitchell 1 headquarters are located, commercial diesel powered trucks are required to be tested annually for smoke opacity. Many other states have adopted California\u2019s rules regarding diesel smoke opacity testing, so get ready \u2014 sooner or later a smoke opacity test may be required for your entire fleet or your customer\u2019s fleet of trucks.<\/p>\n

An opacity test is performed by placing a sensor in the exhaust system outlet and executing a wide-open-throttle; unloaded engine acceleration runs with the transmission in neutral. The sensor measures the \u201cblackness\u201d of the smoke, which is printed to a test report for record keeping.<\/p>\n

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\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Typical Opacity Test Sensor\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/em>Typical Exhaust Aftertreatment System<\/p>\n

While opacity limits vary in different states, it is safe to assume that if a newer diesel vehicle has visible smoke exiting the exhaust system, then something may not be right. In fact, with 5% opacity limits here in California, any visible smoke from a truck equipped with Selective Catalyst Reduction (SCR) is an indication the truck will most likely fail its opacity test.<\/p>\n

So what can you do to make sure your truck passes a diesel smoke opacity test? First of all a visual inspection is in order and will provide a great initial indication of system integrity.<\/p>\n