Hi All,

I have some very basic questions about the viscous coupling and the
best 4WD practices/ operation for my '91 Syncro Camper.  I used to
know some of this stuff, but it's been a while and now I only know
enough to ask the questions. :-)

1) Is it accurate to call the Syncro an "on demand"  4 wheel drive or
All Wheel Drive?  It's my understanding that the viscous coupling is,
in effect "always on"..with the discs always spinning and ready to
transfer power instantly to the wheels with traction. Is that
accurate?

2) Is it nonetheless possible for my viscous coupling to somehow be
broken or not functioning?  I was testing it recently starting from a
stop going up a steep slippery road, and I got the rear tires spinning
nicely but with no obvious, notable help from the front tires kicking
in.  (I am not 100% certain about this...they may have a little.)

3) When I pull out the differential lock knob, nothing happens...no
light, no lock that I can tell -- nothing. What's the likely cause?

4) Under most circumstances where you would want the 4WD to actively
kick in whenever needed (driving in snow for example) is it still
better to keep the differential unlocked?

What ARE situations where locking the differential makes a big difference.?

Thank you.