School District. No. 73 serving Kamloops, British Columbia, located about 220 miles northeast of Vancouver, recently had a "no run" problem with a 1998 DT466E International diesel engine. This particular engine had racked up 381,000 km (about 236,742 miles), so it was just a matter of time when something like this was going to happen.
To get a better picture of this scenario, the durable (electronic) DT466E runs on electric over hydraulic injectors actuated by the on-board engine electronic control unit (ECU), the main component being the Hydraulic Electronic Unit Injection (HEUI) pump. This is a high-pressure oil pump that is fed by the engine lube pump and provides the high pressure oil required by the injection system. If the engine oil pressure is low, then the HEUI system suffers, causing a hard start and poor performance.
We eventually replaced the engine oil pump and regulator, which fixed the problem since we had a lack of oil pressure. We thought that was the end of the issue until this year's winter showed up. It started out with a bang with -20 C (-4 F) temperatures that once again caused the hard-start problem. The driver reported having to crank over the engine for extended periods of time to build up enough oil pressure to fire it up.
Since the cold weather was a factor, I considered using 0-40 weight synthetic engine oil. This designates a very light-weight oil in cold weather and a heavier 40-weight oil for hot temperatures. Typically we were using 15W40 oil for the entire fleet. It was worth a try, I thought, even at $8 a liter it made sense to use a lighter oil to provide an easier and faster engine cranking speed. Synthetic oil lasts close to two times longer before requiring an oil change, so my choice would be justified regardless of the outcome.
It was unbelievable the difference the synthetic oil made. The crank speed increased substantially, and the faster oil pressure build up allowed for a quick start. I am now a firm believer in synthetic oil and will be adding it to all of our HEUI diesel engines. It goes to show why this oil has been used in jet engines since 1972.
Whelan has worked as a school bus and truck mechanic for the past 34 years and is currently shop foreman for the School District No. 73 transportation department in Kamloops, British Columbia. Read more about Whelan's shop experiences at his personal blog site.