L

Lalindra

New Member
Hi everyone,

I have a Defender 110 2.5 (12J), in which whenever i blip the gas pedal at speed or am forced to quickly take the foot off the pedal for braking after a fast pickup, i get a jerking from underneath as if the vehicle is trying to stall !

have replaced all 4 drive flanges, rear half shafts recently. And last year the gbox mainshaft, drive wheel (input gear) and razors in the transfer box...

can someone help ?
 
I had a similar problem on a motorbike a couple of years ago, felt like big transmission lash but turned out to be a fueling problem, ran fine up until high rev acceleration or quick throttle shut off. Re-jetted the carbs and it was fine afterwards, don't know if that helps at all.
 
okay, i changed the diesel filter and cleaned the fuel sedimenter too. There was a load of muck in it (sedimenter).. and the cone element had been placed narrow side down '\/'. So i refitted it right side up '/\' .

Now the problem is much less when you blip the throttle at speed. But when you accelrate fast and then take the foot completely off the pedal quickly the landy jerks, lurches with a lashing sound from underneath a couple of times. If i take the foot off the pedal very slowly this is not there. Also if i press the clutch and take the foot off quickly again no problem.

Really appreciate your help on this as i dont know what is wrong and whether its serious !

Lalindra
 
The cv joints were checked and are fine, The fuel injectors were removed, cleaned (none were showing any major problems) and repressurised. the injector pump was also speeded up a bit, which makes the problem less noticable when slowing down to 10kmph and accelerating again using only the gas pedal (without clutch balancing) , but still if you lift your foot instantly off the accelerator pedal at any speed there is a 'clanking' noise accompanied by bucking as if the landy wants to stop. The bucking causes the vehicle to sort of halt, jump forward and halt and on ....

whats going on ! most of the guys i've talked to here are stumped... could it be good old lucas cav injector pump which is at fault ?
 
it sounds to me like it cuold be play in the difs try turning the propshafts buy hand more than 1 quater of a turn is getting exsesive trasfer box in nuetral. or it could be play in the input shaft to the transfer box or the transferbox itself.
 
Hi again,

Have been busy trouble-shooting. Checked the play in the diffs as you said, the turn is about half quarter (front) and even less (rear) so i dont think diff play is the culprit.

anyway took off the 4 grease caps and put the landy in neutral and no handbrake, and checked for play in the drive flanges. All 4 wheels showed some noticable play (so much for the new rear half shafts & 4 flanges !). Some guys said that its better to weld the drive flange to the half shafts so that it eliminates the clunk and further wear. IS this advisable ?

Also i decided to increase the idel speed/fuel flow to the injection pump (small nut & spring assy on the front RHS of the pump) since idling was lumpy and with a/c it was getting really noticable. That put an end to the lumpy idling and now running with the ac on full blast is possible without the engine trying to die after some time !. IT has also really brought down the level of jerking to almost non existent except for the clatter of the h/shafts and drive flanges.

Any comments....
 
sounds all too familiar even in my landy.

when especially in low gear when you rev hard and release the gas suddenly, i get the same thing.

i just clutch in. no jerks. ok, never do this off road, on road, can 'lah'.
 
Lalindra said:
Hi again,

Have been busy trouble-shooting. Checked the play in the diffs as you said, the turn is about half quarter (front) and even less (rear) so i dont think diff play is the culprit.

anyway took off the 4 grease caps and put the landy in neutral and no handbrake, and checked for play in the drive flanges. All 4 wheels showed some noticable play (so much for the new rear half shafts & 4 flanges !). Some guys said that its better to weld the drive flange to the half shafts so that it eliminates the clunk and further wear. IS this advisable ?

Also i decided to increase the idel speed/fuel flow to the injection pump (small nut & spring assy on the front RHS of the pump) since idling was lumpy and with a/c it was getting really noticable. That put an end to the lumpy idling and now running with the ac on full blast is possible without the engine trying to die after some time !. IT has also really brought down the level of jerking to almost non existent except for the clatter of the h/shafts and drive flanges.

Any comments....
Click to expand...

has anyone found a solution to this? It is exactly the same problem I’m having in my 2011 Puma 2.4…all driveline parts have been upgraded to Ashcroft or similar so it must be fueling…or some switch that doesn’t throw a fault code…
 
This may seem odd but jerking clattering underneath can often be a hand brake problem and may be worth a check.
What happens is when released the system does not come all the way off and as you drive friction heats the shoes and it grips just a bit. When being driven no symptoms but as soon as the power comes off and you put clutch in to change gear or brake the jerking starts.
Easy to check for, after a drive go underneath [ careful ] and see/feel if handbrake drum is hot [ can be very hot ] then there's your problem.
Clean up or replace hand brake expander is fix.
 
The only thing that makes me think something else might be going on is during an off-road test yesterday, I noticed that on a descent in 1L, the bucking was so bad I thought something was going to break under the car so I put the clutch in and came to a stop and as soon as the car came to a halt, the revs jumped up a bit all while the clutch was fully depressed and still in gear…why would revs jump from 900-1100 with clutch all the way down?
 
With your Puma model it does seem to be more engine related but still do check the hand brake.
 
Hand brake barely warm to the touch after long drive...guess I am back to square one... Dealer and Independent verified all perfect, no play or slack anywhere. I assume a fueling issue but there are no codes being thrown so I am at a loss and so is the dealership who wants to avoid spending diag time and not knowing where to start. In second gear high range just driving around and letting off throttle and it is a slow bouncing engine brake pause engine brake pause engine brake pause until it levels out. Incredibly frustrating and the bouncing gets faster when in 3rd gear letting off throttle. 1st gear low descent...forget about it, the bucking was so bad I thought the truck was going to break. Anything else come to mind other than just making the car buck enough to where it throws a code? Checked the brake and clutch switches via live values on BAS Remaps and both work perfectly...brake fuse not blown...at a loss...
 
Got another response on the Defender2 forum suggesting the clutch switch. I bridged the switch to see how that worked and it definitely drove differently but not more smoothly…ended up switching it back because the immediate drop in RPM at accelerator let off was just causing another issue to fix by driving much more smoothly and attentively which I never had to do before…any other suggestions?
 
Just wanted to add more info. Problem still there and maybe getting worse but at this point it is not fun to drive. In 4th gear if I let off the gas and slow from say 50kmh to 10, it will do the bouncing about 2 bounces per second and once around 1000rpm there is an actually banging on each bounce. Also, over pumps it is really annoying almost as iff the bumps increase the effect of some rotational imbalance which multiplies the affect off-road or even just a bumpy street. It really is like a new driver with a bouncy right foot but I’m not touching the accelerator…
 
Any way to confirm this other than the light going out and driving in reverse around the parking lot? I’ve done this but if there is a way using jacks I’d be more than happy to try because I’m going mental! There is also a sound of an unbalanced wheel (cyclical pulsing howl) but all tires were bought new 2 weeks ago and balanced on machine…
 
Good gosh, still an on going problem ! To check that diff lock is out just jack up one front wheel and with main box in neutral spin the wheel. Other wheel on the ground needs to be chocked for movement both ways as handbrake becomes ineffective once any wheel is off the ground. If wheel only turns a bit then the diff lock is in.
 
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