I have 1988 740 wagon non-turbo with 200K
miles, I have an intermittent rumbling
as if the exhaust pipe or engine was touching
some stationary part of the car. The intesity seems
to be varied dependant on the bumpiness of the
road surface. I note under the car thet there is
a rubber bumper just under the raised portion of the
sump at the rear and adjacent to the rear wall of the
main sump. I cannot quite get a finger between this
and the sump but there would appear to be clearance
with the car stationary. I can find no other contact
for this with the car static. Both motor mounts and
gearbox rear mount replaced. I also see four holes
in the chassis members for what would appear to be
a cross brace, just aft fo the engine, has this been
left off at some previous service?