Ducato 2.8 JTD 2001. Motorhome.

MOT advisory, slight play on all wheel bearings.
Is it possible to adjust the bearings on this model? I removed the wheel trim from one of the front wheels, and removed the bearing cover, expecting to see a castellated nut with a split pin through it. What there is, is what looks like a cover over the nut, with a short sleeve with two indentations at 180 degrees, which fit into grooves in the protruding stub shaft. Does this cover just pull off, or does it have to be unscrewed with the nut? It is many years since I have attempted anything like this, so rather than just poke around hoping to achieve a result, I thought it best to ask for advice.

Family member's ducatto campers has had advisorys for various wheel bearings for last 10 years
Never needed one replaced so unless they get worse noisy I wouldn't worry about it

Sounds like a nut locking device if I understand correctly.
Or, located over the nut and the tabs go into grooves in the stub to prevent the nut coming loose.

If the bearing clearance is adjustable the nut might be relatively loose. Controlling the distance between the two taper roller bearings.if which case yes you preload the nut lightly with say 30nm and then back of one flat etc.

It's unlikely on a commercial vehicle. More likely is that there is a bearing spacer with the nut tightened very tightly onto it at say 350nm.
If this is the case the wear is in the actual bearings themselves.

It should be possible to determine which.

I admit I don't know which design it is.

I very much doubt the bearings are adjustable. They'll be angular contact ball bearings butted together and tightened up hard.

I agree with the above. Very unlikely to be adjustable. I don't have experience on the Ducato but that front wheel Hub nut you describe is typical of what you find on a non adjustable set up. The bearing clearance/pre load is controlled by a spacer between the two inner bearing races and that nut will be done up very very tight before being staked over to stop it coming slack. The older, now much less popular, adjustable type bearings were usually, as is described in the OP, little more than finger tight with often a vernier retainer over the nut and the whole lot retained with a split pin. They were, as far as I know, never used on driven wheels. So you would find them on the front wheels of RWD motors - Cortina, Marina, MG Midget, etc, etc. or on the rear of some FWDs - Allegro, etc. Latterly even the RWDs were going to spacered setups and now they seem to be pretty much universal.

If you come across a split pinned one it doesn't automatically mean that it's adjustable though so check carefully before messing about with it. The Allegro was a case in point where BL had been using spacered bearings on the rear wheels of a lot of their stuff - Maxi, Princess/Ambassador, I think the mini was a "solid" type too wasn't it? (can't believe I'm not sure on that, I couldn't count how many Mini hubs I've had in pieces) so we all got used to just doing the nut up "nice 'n tight". Then they used an adjustable set up on the Allegro and people were suffering bearings failing and seizing up, because? mechanics, hopefully not big dealer guys? and home "tinkerers" were just ramming the nut up tight and the bearings were so tightly rammed together that they soon over heated and failed. I well remember seeing a bulletin up on our info board about it which set out exactly the procedure for correctly setting up. There was a horror story floating around at the time that this directive had been issued following the crash and fatality caused when an over tightened rear wheel bearing on a well laden Allegro on the M6 had over heated, seized and caused the stub axle to snap off. The "story" went that the vehicle careened into the concrete parapet of a motorway bridge as a result. Sounded absolutely awful and made such an impression on me you can see I remember it to this day.

Regarding the problem here I think a lot of it revolves around MOT testers being a little frightened of missing something. In the past a wheel bearing with just a little clearance but making no noise when spun and displaying no other faults (like grease leaks etc) would have not attracted any attention. Now though it tends to attract an advisory just so the tester can cover his back.

I had a Mini during that extremely cold winter of 1981. One day (thankfully at very slow speed) the front right wheel came loose and drive stopped. I came to a stop with the wheel about to fall off. The retaining nut had come away complete with the split pin and threaded end of the CV joint. The nut was supposed to be tightened to a torque then moved to the next hole/slot combination so the split pin could be fitted. It was common for them to be forced too far around and in my case the uber cold embrittlement did the rest.

I was hoping someone might confirm but I recollect 'adjusting' the rear wheel bearings of my 1998 Ducato. I can't remember what made me examine them but found the nut needed tightening to get rid of the play.

However shortly afterwards I had to have the bearings replaced so the play might simply have have been the first stage of failure and they weren't meant to be adjusted?

Thank you very much for your replies gents. In view of the comments received, I will not attempt to adjust the bearings, and just hope it gets through the MOT again. I don't think the play on the bearings is excessive, there is no undue noise from them, and the vehicle has on!y done 65K miles. Thanks.
Ex Greeny.