Block-up rebuild on my 2000 D2 4.0, completed in May. Since then, I have only driven a little over 200 miles. I put in a performance cam from D&D as part of the rebuild. I also replaced the u-joints and greased the front shaft.

I am not certain that the way I am typing this will be correctly described, however I hope I can explain well enough to convey the situation. If I am incorrect in which part does what, please bear with me.

Ever since I got the Disco back on the road, I noticed an uneasy acceleration from a coast. By this I mean when accelerating from a "coast" when I believe the driveshaft/drivetrain is not under torque, when the driveshaft accelerates, there is a clunk/thud that I am pretty sure is the shaft speeding up/engaging/torquing (I am not sure how to put this exactly). This happens a split second before I actually feel the acceleration. It is the same loudness/feeling, whether it is a slow acceleration or a strong one. This does not happen if I am taking off from a standstill or if I am already accelerating and accelerate harder.

I mentioned the cam upgrade, however, I doubt that it would cause this. Though, I do not have a reference to how it was before the rebuild. Full disclosure, I never really drove the Disco before tearing the engine apart. I acquired it for my sister. She drove it about a year and blew the head gasket. I stored it for about a year and only drove it around the block every few weeks to keep the battery charged and add a little fuel. When I was ready to put the time into it, the 'never ending journey' began. And here I am.

My thinking is that if this is not what is to be expected from the cam upgrade, I must have made a mistake/overlooked something on the driveshaft rebuild. For the driveshaft, I followed the thread from antichrist.

I am hoping someone has ideas of where to focus on. Thank you in advance for all positive input.

Ross
2000 D2 4.0

 

Would not have anything to do with cam, pull your front drive shaft out and engage cdl and see if "clunk" goes away if so there is your problem.

 

lr2001,

I do not know what the cdl does. So, if that is the issue, what is the remedy? Does engaging it solve the problem and that's it? Or do I have to do something to the cdl to resolve this?

So, my next step should be to research how to engage the cdl. Take off the shaft, engage the cdl, replace the shaft, drive and see how it does?


Thanks for the info.

Ross

 

Did you replace the centering ball when rebuilding the drive shaft, if not that could be your problem. As already mentioned, remove the front drive shaft and drive in hi lock to see if you still have the problem.
In the mean time do not drive it much till you find the problem.

 

Cdl "center differential lock" on the top of your transfer case the is a small stub sticking up use a open 10mm wrench turn 1/4 turn towards passenger side if laying under truck with your head toward the front. If you take out front drive shaft and don't engage cdl you could put in drive and rev engine all day and go no where if you engage cdl it becomes a rear wheel drive and off you go. Get it?

 

Thanks for replying guys.

Mike,
Yes replaced the centering ball. Other than the driving you guys suggested, I will not drive it until I get this worked out.

So, if I engage the cdl and the problem goes away, what is it that I would likely be looking at then? It will probably be Tuesday before I can get to it. Just want to get a good idea of what to expect.

Again, thank you.

Ross

 

If you pull the front drive and the engage the cdl and problem goes away then something went wrong the the rebuild. Do you have any vibration or anything like that? Now you may remove the drive shaft and the clunk may not go away it could be a number of things front diff gears worn front diff low on fluid from in proper care. Could be transfer case, changing to a 75-140 synthetic fluid there could quiet it down a lot. Are you sure that you greased the rebuild real good? Could be a transfer case mount and the list goes on.

Good luck Ross

 

Even with the shaft removed, if the sound goes away its still not 100% it is your drive shaft. I have some front end noise I havnt found yet that was present before I rebuilt my shaft and disappeared when removed. I did a full rebuild, with all u-joints and centering ball, and the exact same sound is still there. It could also be related to your front axle somewhere. Replace with higher weight fluid and see if it quiets down. I think mike also suggested to me that the bolt on the flange where your drive shaft connects can come lose and needs to be tightened to some obscene torque like 360 ft*lb or something.