Search has been done but I haven't found anything with similar symptoms other than transfer chain failure, H-L shift movement failure, or viscous coupling failure in which the coupling locks up - none of which seem to be the case for me.
- Driving normally, no unusual noises or vibrations, normal power levels, car has been driven regularly in the preceding weeks.
- I had slowed down to ~30km/hr due to bad road conditions and when I applied power (maybe with a little vigour...) to resume cruising speed I lost all drive: engine running fine, just no forward movement and a rather nasty grinding/buzzing noise.
- Managed to coast to a safe location, investigate and fail to resolve, recover home and investigate further.
- No movement regardless of gear selection
- All driveshafts intact
- Transfer box motor makes noise and instrument panel shows successful movement from H to L and back again
- A significant grinding noise in gear (D, R, 1, 2 3) that varies in speed depending on whether the transfer box is in H (high speed buzz/grind) or L (low speed buzz/grind)
- Grinding noise persists slightly when returning to neutral before quietening down
- Vehicle rolls freely when in gear (manual push 1-2m back and forth)
The fact that the noise changes frequency depending on selection of H or L leads me to believe that the transfer mechanism still works, and that the problem lies on the output side of the transfer box.
Has anybody experienced similar with a viscous coupling failure? The more common failure modes seem to be total lockup with resulting tyre squeal when cornering, or movement but in 2-wheel drive only.
Thanks in anticipation.