MaxxForce DT Diesel Engine No Run Problem

imported_John Whelan - September 10, 2019
I posted a similar video like this one a while back with the same scenario. I thought it was important to show again the importance of what to check when a diesel fails to run. The saying everything happens in threes is very true within our fleet. I've seen it happen many times because the groups of buses we purchase together have identical specifications and sometimes 2 similar mishaps may happen a couple of weeks apart. In this case the exhaust brake stuck on and looking back if I would have checked out the components first this bus could have been mobile again sooner than later.

But it was broken down in a turning lane at a busy intersection so the only thing that mattered at the time was to get it out of there and back to the shop. The laptop was not telling me anything and nothing else clicked until the next day when I saw the injection pressure at a normal level while cranking. Then I remembered the previous failure and that sparked a eureka moment. This time I could show in the video the actual seized exhaust brake air cylinder and tapping it back in to place.

Once I was able to remove the clevis pins I found one that was very stiff. The return spring in the exhaust brake cylinder could not over come the stiff linkage. I proceeded to remove the cylinder for testing on the bench and it checked out OK. The breather filter that allows air to escape the opposite side of the internal piston was plugged up. This breather would also cause some resistance against the internal piston of the cylinder.

So once everything was cleaned up and lubricated a road test was the final step. There were no incidents on the road and luckily a small repair like this one was a relief since a lot of MaxxForce no run conditions involve money and labor getting in to the injection system. The last no run on a MaxxForce DT cost a couple of grand replacing the high pressure oil pump. The only expense with this repair was a two hundred dollar tow truck bill and a couple of clips for the exhaust brake cylinder clevis pins.

In conclusion if you have a MaxxForce DT diesel engine that only runs for a few seconds and there are no engine codes check that exhaust brake cylinder.
School Bus
Diesel Engine
maxxforce DT
no run