I’ve been chasing down a phantom engine noise since the end of last season when I put the bus to bed in the garage with what I first thought was simply a worn out muffler. Spring 2015 came and I eagerly set about tuning and fixing the camper for further adventures. The replacement Bugpack single quiet pack muffler went on fine and I also found one of the header to heater box gaskets was worn out too. Much to my surprise when I cranked it over and it still sounded like a box of hammers. I immediately began thinking of how to track down a new 2 litre boxer-motor to succeed the 1800, but I was too hasty.
A few days later while I was lying under the bus in my overalls contemplating its greatness, I began to idly twiddle with various bolts, you know just checking them. Suddenly there it was, a loose exhaust stud on number one at the head. I grabbed a 13 mm socket and popped it out, the nut was firmly on the stud at what I thought must be the right distance to torque up. I cleaned it up with some motor oil and gently, but firmly, put the works back in to the slot. It went in perfectly and snugged up like new. Then the moment of truth, I fired it up, music to my ears, all those crazy phantom mechanical sounds were gone and it drove like the wind with no back fire. It feels like a new engine, I now suspect the loose head bolt was working its way out getting louder over the last couple of years. The lesson here is, what sounds like bad lifters, a loose valve train or the like could simply be odd sounds being produced due to a leaky exhaust system.