Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: coz on October 05, 2007, 10:16:42 AM

Title: 2.5 td XJ knock, bang noise
Post by: coz on October 05, 2007, 10:16:42 AM
ive got a xj 2.5 td 1999 facelift done 90k

developed an occasional thud, knock niose when pulling off - more noticeable if car is loaded up or trailer attached

My mechanic has checked all UJ's, shock mounts, exhaust hangers etc and found nothing

he said gearbox output shaft had some play but not hugely significant

Ive just read about the chain thing in transfer box, could it be that, its doing it in 2wd tho

any ideas
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Post by: Manda on October 05, 2007, 10:48:40 AM
I may be wrong and they'll tell me if I am, but it could be the LSD in you back axle. They get worn out and clonk and bang when they're warm and you pull away.
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Post by: coz on October 05, 2007, 11:09:34 AM
i thought only the 4.0 had LSD

but am waiting to be corrected -
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Post by: mikeh on October 05, 2007, 12:39:19 PM
Quote
LOW SPEED KNOCK
Low speed knock is generally caused by a worn
U–joint or by worn side–gear thrust washers. A worn
pinion gear shaft bore will also cause low speed
knock.

DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted
into gear (or the clutch engaged), can be caused by:
² High engine idle speed
² Loose engine/transmission/transfer case mounts
² Worn U–joints
² Loose spring mounts
² Loose pinion gear nut and yoke
² Excessive ring gear backlash
² Excessive side gear/case clearance
The source of a snap or a clunk noise can be determined
with the assistance of a helper. Raise the vehicle
on a hoist with the wheels free to rotate. Instruct
the helper to shift the transmission into gear. Listen
for the noise, a mechanics stethoscope is helpful in
isolating the source of a noise.


From the book  :wink:
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Post by: coz on October 05, 2007, 01:01:22 PM
thanks, thats helpful, will check it out more
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Post by: barttheguinnessguy on October 05, 2007, 04:42:05 PM
Mine did the same sort of thing. Turned out it was the shocks moving on the bar pins :wink:
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Post by: coz on October 05, 2007, 07:51:26 PM
Quote from: "barttheguinnessguy"
Mine did the same sort of thing. Turned out it was the shocks moving on the bar pins :wink:


where did you get them from
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Post by: Bubba on October 05, 2007, 08:39:27 PM
might be might not
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Post by: Dave69 on October 05, 2007, 08:42:19 PM
the derv jeeps had the LSD in the rear and for some reason they weren't fitted to the petrol.

clunking or juddering from take off could be the clutch pack in the rear diff not working or it could be the clutch. When i had mine the rear diff was fine but i found the clutch was knackered. worn finger splines and the pressure plate springs had worn away good parts of the pressure plate
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Post by: Bubba on October 05, 2007, 09:30:14 PM
i think you may have wrote that the wrong way round it may be a sheared gearbox or engine mount
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Post by: barttheguinnessguy on October 07, 2007, 06:22:04 PM
Quote from: "coz"
where did you get them from


Rocky Roads Outfiters. http://http://www.rocky-road.com/xjbarpin.html
Title: Re: 2.5 td XJ knock, bang noise
Post by: Sam on October 19, 2007, 06:37:13 PM
Quote from: "coz"
ive got a xj 2.5 td 1999 facelift done 90k

developed an occasional thud, knock niose when pulling off - more noticeable if car is loaded up or trailer attached



aye mine does it too (has done for ages- bout a year) two of my mates with the same cars theres does it to.

between the three of us weve found it v.hard to see whats wrong (all above mentioned things checked and fine). mine started after i trashed a crossmember and knocked the transfer box out of place (since been fixed but still does it) we think its the prop knocking on something but cant suss it out.

i ignore mine now ive gotten used to it (although when its in 4WD and pushed real hard like when trying to get up a major steep hill offroad it sometimes feels like the prop is coming through the passenger floor :oops:

if you fathom it out let us know  :D