I have a Daihatsu fourtrak (type F75RV-MBT its a four seat van body)on loan for the weekend as an extended road test before buying. The truck goes very well and has passed all tests so far except one; the 4x4 system does not work! There is ample power to the rear wheels, but nothing to the front. This is quite bothersome, as I am contemplating purchase of a 4x4 to enable me to do quite a bit of logging over the next year or so. The truck is fitted with 'automatic freewheel hubs' It was built in the early 90's

So, to the symptoms - When I try to engage 4x4 in high or low transfer box the dashboard light illuminates and I can feel something going on in the gearbox regions. However, when power is applied, the back wheels spin and the back end flails about like a demented pendulum. The front end remains where it is, as if it was stuck there with superglue. There are no funny noises coming from anywhere during either 2x4 or 4x4 running periods. The tyres are OK (they passed the MOT test yesterday), but getting towards the end of their useful life.

I have tried going forward 20 m then backwards 5 m in 4x4. That didn't work.

I have tried quick changes at snail pace between 1st and reverse in 4x4 H & L, to jolt anything that may be stuck. That didn't work either.

I have tried low speed selection of 4x4 in H&L.
That didn't work.

I have driven miles over stoney lanes to rattle things about. Guess what?
That didn't work either.

The only other useful information I can give is that the front hubs are warm (tepid) to the touch after a short run, whereas the rear hubs are stone cold.

I strongly suspect the truck has stood idle for a year or so, and the automtic hubs have got gummed up. Is this likely?

Or, are there other, more sinister and expensive problems that may be lurking beneath the surface, waiting to empty my wallet?

I wait for your replies with bated breath!