Monday, December 25, 2017

Mercedes MBE Diesel Engine Pusher School Bus



The cold start on this bus was perfect without any hold ups. It was plugged in and the batteries are obviously in good shape. Of course with most diesel engines the white smoke is normal with incomplete combustion going on. Heat from compression is low in this case so it takes a while for normal combustion temperatures to occur. The rule of thumb with diesel engines in my book is to put the engine to work as soon as you get normal oil pressure or at least make sure the high idle mode is on. Idling a diesel in cold weather is not a good practice because of the build up of carbon and related combustion byproducts that happen with cold starts.

These MBE 900 diesels are good solid engines except for the emissions which was adapted to the original block in 2007. The blocks can not be swapped from non emissions to these 2007 models because of added modules that were engineered to meet emission standards. I know this from experience we have a 2008 MBE that has a cracked block and no one can find me a bare block for it. There are plenty of non emission blocks around but nothing newer. The long block is available from the dealer but at a huge cost and a core charge that we would not get back due to the crack in the block.

When the warranty was up with these engines we were in for a lot of challenges. The engine codes were running away on us with daily occurrences with the EGR valves, DPF diesel particulate filter, EOS electrostatic oil separator along with boost and charge air codes that did not let up. Two of these pushers were sports run buses and almost every trip they would radio back and tell me the engine was coding. One saving grace was the ignition key could be cycled on and off which would reset the code until it came back again. But this would stress me out regardless being helpless with the bus so far away. One bus was 4 hours out of town and I spent hours trying to line up a service call to do a parked regen or else the bus was dead in the water.

Eventually these 2 bad boys were taken off of the sports run and we started using newer Cummins ISC diesel engines. The pressure was off and if you have read any of my other posts Cummins is my choice for a diesel engine medium duty ISB and ISC models. Yes they don't last forever there are quirks and failures but an extremely smaller percentage compared to other diesels on the road. Preventive maintenance had proven to extend down time and the extra cost is money well spent.

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