I hope this is not too far off topic, some guys here seem to have a wide range of knowledge so I figure someone may know whats going on.
I've got a 1995 Nissan Civilian (6 cyl diesel bus) and it's exhaust brake chatters intermittently. Sometimes when it starts it will chatter for 10 or so seconds, and if you jab the clutch (which operates one of the exhaust brake control switches) it will also start chattering.
When it chatters it looks like its trying to operate and then drops back off, it does this at a 5 or so times per seconds - makes a br-a-a-a-a-a-p sound if that helps!
The vacuum hoses to the actuator and vacuum solenoid wiring look good and the butterfly valve mechanism moves freely when hand operated.
Any pointers on possible causes greatly appreciated.
Thanks.