This is going to be hard to describe. When the DII is going up hill or exerting force it sounds kind of like the sound you here when using the engine to brake downhill. The noise slowly dissipates the faster I go. This is probably something that a forum cannot help me with but thought I would give it a shot and see if you guys could give give me some idea of things to check. Not sure if it is something related to differential engine or what????

 

Where on the truck is it coming from, what have you checked so far, has your front drive shaft ever been rebuilt if so how often do you grease your grease fitings, what about your brakes, do you have a caliper dragging?????

 

Well rebuilding the front drive shaft was next on my list. I just looked and I do have a grease fitting (zerk) on the universal joint end but no grease fitting on the crosses of the hookes joint. I am assuming that is the original drive shaft and has not been rebuilt. I got your pdf so I will begin to order parts etc... to start this.

While I was under there I noticed that it looked like the inspection cover was missing from the bottom of the torque converter housing. Im going to order the cover gasket and screws but not sure if with all the mudding/off roading if I may have screwed something up in there?

 

Are you going up the hill when the rover is just started in the morning?
That sound may be the head to exhaust manifold junction a bit wide until the manifolds heat up.

I would check the exhaust manifold bolts for a few loose ones.

Warning - these will SNAP OFF so careful. Just try to budge one a hair.

But, if one does snap off - then that was your problem. Not enough clamping force.

If one cylinder is leaking - you'll hear a slower pop pop noise.
If you have a problem at the "Y" pipe junctions, then you'll hear 4 cylinders popping.

Warning - the "Y" pipe nuts on the studs will SNAP usually if disturbed.


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There is another strange noise.
In the morning - when I first start up the Discovery I or the Discovery II
There is a slapping or clattering noise.

Been there for years and 80,000 miles.
Goes away in the first 3 minutes.
Never to return.
Until the next morning.

 

front differential whine? That is what came to mind reading your post. I remember test driving a Disco years ago that had a really prominent whine when getting on the gas...not sure if it was normal or not, but it was a dealer vehicle.

FWIW, mine isn't very whine-y, but apparently the type of oil in the transfer case/diffs can make a difference.

Definitely get the front prop shaft done. The cover was gone off the torque converter? Ack - get that remedied, asap. On my former Isuzu Trooper - the shop left the cover off my flex plate, and I am convinced it did something to eventually screw up the tranny (granted, it was a 4L30E which is as fragile as a Faberge Egg), but I'd still get things sealed up quickly.

 

Well we have not owned this long but have had some off roading fun in both mud and some water that would go above that diff. I will try to find a good thread on changing out the fluid (or if anyone knows of a good sticky) but what do people suggest in terms of fluid brand in these?