See full version: Diesel Engine Smoke: Blue, Black, or White
With a high-hour engine, things like valve seals and piston rings that are worn out can be a cause for excess blue smoke emission from your exhaust. In either case, an experienced mechanic will be needed to make a definitive diagnosis. Your engine may be near the end of its useful service life.
White smoke can be caused by either excess fuel or an internal coolant leak in your engine. This is a case where you’ll probably want to call in the diesel pros, but here’s a diagnostic tip:
Another potentially frightening scenario is a leaking turbocharger seal. If your engine is turbocharged, the air-intake side of the turbo, as well as the exhaust side of the turbo rotor, has a high-pressure oil seal installed. Remember that these turbocharger rotors often spin at speeds more than 20,000 rpm, so lubrication for the bearings that support the shaft is of paramount importance. But sometimes the seals wear out and allow oil accumulation in the air intake system. This is a dangerous situation that needs immediate attention, because a diesel engine can run on lubricating oil. With a pressurized oil supply to your turbocharger and a leaky seal on the air-intake side of the shaft the turbo blades are mounted on, you will end up supplying raw engine oil to the combustion chambers of the engine. In this scenario, even with the fuel supply to your engine completely shut down, the engine could go into a runaway situation. A runaway diesel running on the engine’s crankcase oil will run until the engine oil is depleted and the engine seizes due to lack of lubrication. more
Your diesel engine is equipped with a governor that helps control the amount of fuel that gets delivered to your engine’s cylinders depending on the load your engine is experiencing. The occasional puff of black smoke that may occur when you suddenly push your throttle to the max is really nothing more than the governor shooting some extra fuel into the injectors before the engine catches up and comes up to rpm. With the advent of electronically controlled diesels this anomaly is beginning to fade away fast. [links]
Overheating is a common symptom of marine diesel engine blockage. Marine diesels should run at 180 degrees Fahrenheit. When the temperature goes above 200, start getting worried. Dialing down the RPM’s may allow the engine to recover and run well at a more leisurely pace. Overheating is difficult to diagnose, and the only real way to solve the problem is a systemic examination of every engine element, i.e. trial and error. Here is a starter list of parts to examine:
Please suggest more options in the comments below. I have specifically not included catastrophic failures like water jacket blockage or cracked heads which are alarmist ideas and not the common answer though certainly a worse case scenario to keep in mind.
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Colors point to problems like overloads, internal oil leaks, or contaminated fuel. Follow this summary to identify problem areas and take the suggested actions to resolve the problem as soon as possible. It's not an "end all to end all" list by any means. But, it'll get you started.
* Clogged air filter
Remove the filter and replace. If cruising in an area where air filters are unavailable, tamp the filter on a hard surface to remove as much dirt and dust as possible.
* Misfire on startup
If the engine misfires, but starts--this signals a compression problem. Often, an overhaul will be needed to resolve the problem. Sporadic misfiring signals dirty fuel or water in the fuel. Change out fuel filters. Drain the fuel tank, clean it, and refill with fresh fuel.
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