It’s a great feeling to find a problem on a diesel engine and repair it without any comebacks. In the mechanic’s trade a comeback is a dirty word. Sometimes it can’t be helped but it still happens. However when you get a win it makes up for any negative occurrences.
The diesel engine in this video had been acting up for months off and on. One day it would have an engine code then suddenly nothing would happen. The intermittent problem is the worst when you’re trying to nail it down. The driver’s story has to be extremely accurate with the time and place the problem pops up.
Then we go out and follow the same route the bus goes on to get something to happen while hooked up to the diagnostic software. The speed, engine temperature, grade of the road are all factors when it comes to troubleshooting an issue. The bus in the video had a DTC which was a loss of boost pressure.
We located the leak and repaired it with a new EGR cooler, elbow and transfer pipe to the exhaust manifold. Once the exhaust side of the engine was sealed properly the engine code has not returned. The diesel engine being a 2007 is emission controlled so it has a diesel particulate filter.
In a previous post this engine was flushed out with a machine that is supposed to get rid of all of the soot. This worked out well in my opinion and helped with the end result. The main focus I was looking for was to clean the soot off of the turbocharger which has never been cleaned up.
I’m sure it’s in much better shape after the cleaning process. The thing that happens to turbochargers that get a soot layer on the turbine wheel is they slow down which effects turbo boost pressure. A low pressure of course causes low power and an engine code as well.
We have added a parked regen to all of our Mercedes diesel engines when they have an oil change. That is every 15,000 km. This will keep them cleaned out and it will help avoid unexpected engine codes. Most times the soot and ash that collects on everything in it’s path produces an engine code. For example the turbo boost sensor..when it’s all coked up the reading changes and a code flashes up on the dash.
This is commonplace and once you get used to the step by step procedures to troubleshoot the diesel engine in question the experience makes you better at repairing them. You get more efficient and knowledgeable…you also respect the technology more instead of getting frustrated because of not knowing where to start. The more you work on them the better it gets.