disco diff lock

[mr_clarkson]

ok, i will start from the beginning this first bit i am unsure if its related but may possibly be o will add it and see what you think.....

The other evening i was on a very muddy and waterfilled site in my disco, played for a short while and probably got the underneath well soaked with water.......then drove home `15 miles or so, no problems.
The following morning i got into the car and went to drive to work, reversed out the drive onto the road fine, then pulled away and got a horrible noise, i can only describe it like metal tank tracks, sqeeking and grinding, stopped, had a quick look underneath to see if anything was stuck on the prop ect, and afetr not finding anything carried on, the noise continued only for 50 yards or so then seemed to clear up, i assumed that maybey there was some crap in the brakes and thought nout more of it.......................

onto today, i took part in my first rtv trial and after getting stuck i had people asking if i was in diff lock (wich i was in low box[forward left on the lever]) then a couple of people comented that they didnt think the back wheels were spining just one font but neither of The back, i then got cross axled and grounded out between 2 banks, i put it in gear and checked the front pas side was spinning and the rear drivers side. but all day people have been asking if im having trouble with diff lock,

Would the difflock work intermitently? or prehaps stop working when the rear wheels are on the deck and effectivly under pressure? how can i check for certain to findout if it is ok or not?

its a disco 300tdi by the way. oh and should a 300tdi have a dash light for difflock? ncos mine doesnt seem to never has? maybe its just not working?

sorry for the long post
cheers
jon

[andymurph]

yes it does have a light on the dash. sounds similar to mine- cause-difflock engaged switch screwed in too far, the lever moves to what seems to be the right place, but the difflock can't engage. just unscrewed the switch a bit, shorted out the wires to check the bulb works, plug it back in, now all ok. (this is a best case scenario for difflock not working, it may also be the shift mechanism seized)

[bilge rat]

yep you have a diff light , poss a switch fault is the same p/no as reverse light switch . i would sort this first you may have wound up the trans the other night but cant comment on the rest. iff you go underneath .put your hand on top of the transfer box just behind the front prop and you should see or feel the switch . iff you pull the wires off and bridge the wires the light should come on with the ign . iff it does it might be worth a switch before you go any further ..alan

[bilge rat]

yes it does have a light on the dash. sounds similar to mine- cause-difflock engaged switch screwed in too far, the lever moves to what seems to be the right place, but the difflock can't engage. just unscrewed the switch a bit, shorted out the wires to check the bulb works, plug it back in, now all ok. (this is a best case scenario for difflock not working, it may also be the shift mechanism seized)

beat me too it ;)

[mr_clarkson]

thanks for the rplys wi;; look at the switch tomorow, so is the difflock engaged electronicly via this switch then?

[mr_clarkson]

ok, i have some news, couldnt wait untill tommorow so have pulled the wires off the switch, bridged them and hey presto i little light comes on on the dash, ok so now, is it a faulty switch.......in the dark and wet and the underneath covered in crap i managed to get a spanner on it and remove the switch, the terminals seem a little loose, but after setting my camera up to record the dash i reconected the wires and pushed it by hand, and yes it works................

so, what now? when i put it in diff lock in high OR low box the car still goes (in high or low as selected) but obviously the diff lock isnt on? so id the diff knackard? or maybe the switch is in to much? the lock nut was wound right to the top i.e. it was in as far as it can go! so how can i refit and know its in the right place?

cheers
john

[mr_clarkson]

well, have tried refitting the switch at various levels and cant seems to get a light to come on so looking like the transfer box is knackard :(

[mr_clarkson]

well, i have put a new switch on it today (£20 :eek) still no joy :( i was told by the garage to engage difflock and on tarmac when turning in a circle should feel it snagging if it is working, well there was nothing difflock was the same as being out of difflock, so looks like my difflock is not working, whats next, linkages? or just go straigt in forr a new transfer box? if it is the linkages how do i get to them? tried looking from underneath and what i could see seemed tight, no play ect?

also whilst underneath i noticed there is some play in the prop from the transfer box to the front diff, you can turn it approx 8th of a turn left and right but the rear one is solid? is this normal?

cheers
john

[mr_clarkson]

oh, and ment to ask aswell, underneath at the botom of the gearbox there is a hole, looks like it is threaded should there be a bolt in here? it right at the bottom kind of on the bell housing i think+

[skip2]

Is the 300 like the 200

On the 200 the linkages are accessable from the cab, one has to take off the centre dash, the low-high knobs and the covers which i think are riveited in.

Then take some covers off, mine were full of mud, some clavis pins etc.

Cleaned all mine up worked ok after easy then taking box out.

[sotal2]

oh, and ment to ask aswell, underneath at the botom of the gearbox there is a hole, looks like it is threaded should there be a bolt in here? it right at the bottom kind of on the bell housing i think+

Sounds like the wading plug hole - you buy a plug to go in there when you go wading, then you remove it afterwards.

A standard plumbing fitment fits and is a lot cheaper

[stevied645]

Is it possibe the grinding noise you were hearing be a snapped rear half shaft? And it would look like everything was fine when you had no weight on the rear wheel but when the weight was on it was slipping. Just a thought.

[bilge rat]

could be ?. dont iff you engage diff lock and jack up a wheel you cant turn it . i know iff you remove a prop it wont drive unless in difflock. i know on mine when you engage diff lock you can hear a loud click in the box. when i went round billing the diff lock was a pig to engage . had a look when i got home and some how the little rod had a nasty bend in the middle . straightened out and o.k. i would check the linkage make sure your getting full travell . disconnect the linkage at the box and operate it with an adjustable or something . as already mentioned you can access everything from the top . i would try everything before taking it out ..alan...

[mr_clarkson]

thanks for the advice,

regarding hole in gearbox bellhousing, wading plug hole sounds sensible, so i can stop worrying about that.

as for the diff lock not working (definatly not) i will see if i can get time tommorow to remove the center console and check the linkages, but the thing i dont understand still is why it is driving in dif lock even though diff lock isnt engaged? anyhow, i am really hoping i will find a problem with the linkage so i dont have to go messing with the trans box.


on a plus note put a nice new k and n filter in it today, What a differance!!!!! drves so much nicer now and i am sure the fuel econamy seems alot better, was getting 25 to the gallon before tops but seems more towards 30 now :) which makes me very very happy, or maybe its cos derv has come down in price so just seems better lol.
turbo seems to wind up alot easier now with the new filter to :)

thanks for all the help so far, any more comments welcome and appreciated, sure i will have more questions once i have seen the linkages.

john

[mr_clarkson]

k, update so far,

i have removed the center console and had a fiddle with the levers, then got a bit nasty with a jack handle, i have jacked up all the wheels (one at a time) and tried firstly in difflock - the result was the same on all four wheels i could turn the wheel maybe an 8th of a turn at most back and forth but that was it, then with difflock off they all span freeley, this was done with the gearstick in neutral.

so from what i can gather this means my difflock IS working afterall? just for some reason the dashlight is not coming on so going to have a fiddle with the switch now would i be right in thinking that to fit the switch i should put it in diff lock then screw switch in as far as it will go plus half a turn?

many thanks
john

[mr_clarkson]

thanks for all the help guys, it now seems to be working as it should :D touch wood :) just needed to get the switch right in for it to come on, i find i have to reverse to get it to switch off though? but not always i assume this is normal.

just wondering about the amount of play in the wheels when difflock is on though? i think this is down to what i said about play in the front prop earlier? the rear prop is solid no play, but the front prop can be spun by hand about an eighth of a turn left and right, is this normal? or does something else need replacing?

many thankis for the help
john

[bilge rat]

thats all normall. iff your on soft ground the diff lock will more than likely come straight out but iff the ground is firm it is quite normal to have to reverse to get it to come out..alan