Super select dilemma.

[Keeno]

Under what conditions would the super select gearbox attempt to engage 4 wheel drive?

My NJ has on two separate occasions tried to engage 4 wheel drive without me moving the gear selector. On both occasions I was towing a ski boat up a long steep road after having used 4L to pull the boat up the boat ramp.

I was definitely in 2H before exiting the boat ramp area.

The climb is about 12 km long rising about 950m and I?m in 2nd gear all the way.

I do the climb regularly without the boat and have had no re-occurrence of the problem.

There is no visual damage of the vacuum actuator and the vehicle goes into and out of 4 wheel drive without incident. The problem may have something to do with using 4L it pull the boat up the ramp or the extra weight during the climb. I just don?t know.

What can I check?

[dolphin]

i can only think of maybe there is excess play in the selector shaft at gearbox side or a faulty actuator. the vacume actuators [ 2 of ] under bonnet normally let you know via the flashing instrument lights [4WD] if there faulty as they will keep on flashing plus you wont get into 4WD so it must be down at the box end.

[psproule]

You have run out of manifold vaccuum from being at wide open throttle up the incline, and / or you have a vaccuum leak. The front diff disengage is held open (in the 2WD position) by manifold vacuum. Look for leaky pipes, or the actuator could have a pinhole in the diaphram.

[Keeno]

You have run out of manifold vaccuum from being at wide open throttle up the incline, and / or you have a vaccuum leak. The front diff disengage is held open (in the 2WD position) by manifold vacuum. Look for leaky pipes, or the actuator could have a pinhole in the diaphram.

That pretty much what think the problem is because as soon as I get onto the flat everything appears to be working fine.

As for the throttle position, I sit between 2500 and 3000 rpm.