My 60 plate MAN has recently developed a problem with the engine brake, the gearbox changes down, a symbol on the info panel indicates engime brake on but there is no actual retardation. Any body have a reason why?
Its about ready for the scrappy at that age… 
Seriously though, the exhauster is probably just stuck and needs a bit of TLC with a big hammer, sure i’ve read here somewhere that these can give trouble.
Needs to go into a dealer sooner rather than later. It is one of a MANs common faults, the valve shaft shears off inside the exhaust, it can go one way, out, or the other way, into the engine. Mine went and so have a few others at work. It isnt a five minute or five pound fix either.
Juddian:
Its about ready for the scrappy at that age…
True, good luck ever getting it fixed…