Greeting to all, I am new to this forum. Have read a lot and learned a lot. Thanks to everyone for sharing their knowledge.

I'm having a noise issue with my 2003 V8 Discovery HSE automatic.

The issue arose 2 days ago and has gotten slightly worse. At first I thought it was a wheel, but not sure.

Noise:

- Cricket-like chirp in front end that starts around 10mph and disappears/tapers off at 50mph. There is a secondary intermittent higher pitch chirp, like a second or third harmonic from the fundamental noise that occurs occasionally.

- The noise sounds rotational and cuts out when i either rock the car or am on an incline. The noise ONLY exists when I am accelerating in gear. Not in neutral or park.

- The noise has a slight wobble to it and sounds on the "lighter side", not a dense grind or clunk or tick.

- The noise disappears when I am going up hill.

Checked the brakes, belt tension seems fine...no visible wobble in pulleys.

My diagnosi(s)....guestimations.

U-joint drying up or warped that is scraping under load.

Wheel bearing drying up and/or failing. Guy at local autozone said he though it was a seal broken and was a bearing noise.

Pulley/water pump failure...would that make a chirping noise? the disco has overheated a couple times recently and has seemed to leak some antifreeze somewhere in the vicinity of where the cooland hose meets the the engine. There was some apparent splashing on the undercarriage but i couldnt really tell if it was just from AC compression. My logic is that if the water pump failed, that would explain coolant leak and progressive noise. I'm pretty sure the pump is rotational.

Maybe even the noise is water pump / coolant leak spraying onto belt? Far fetched i know.

Any guesses or suggestions appreciated. What to check, look for, ruled out.

 

That sounds like your double cardon joint failing, when it does fail you will be buying a new transmission for you truck unless you stop driving it and have it taken care of now.
You need to have the front driveshaft rebuilt.

 

X2 on all he said - it will come apart and impale the tranny - dealer will want serious folding money. There is a DIY how to write up here Propshaft Rebuild - Land Rover Forums - Land Rover Enthusiast Forum
and even if you have an indy shop do it you will be better informed.

Coolant loss is unrelated, but more dangerous, as it will kill engine. Rent/borrow a coolant pressure tester from auto parts store and test for 30 minutes at 20 PSI, to find leak. Could be hose, could be head gasket.

Truck stays at home. Drive back up vehicle. This is no time to take off for Vegas on a road trip.

 

It looked like a normal U joint at the front differential. So would it help to attempt to grease it?

The noise does seem more towards the front. Is the standard U joint more prone to fail than the double cardan?

Are there distinct symptoms differentiating the two?

Also if anyone has generic part numbers, i plan on buying everything and bringing it to a mechanic for labor.

thanks.

 

The front joint will have a grease zerk in it from the factory. The two rear joints nearest the transfer case will not have zerks from the factory.

Bottom line: If the front shaft is making noise, and you do not know if it has ever been rebuilt with three grease-able joints, STOP DRIVING THE VEHICLE and REBUILD THE FRONT SHAFT as per the sticky Savannah provided for you.

Failing to do this, and continuing to drive the vehicle, is asking for a shaft failure (which, if you're lucky, will only destroy the shaft...but more commonly will puncture your transmission, requiring a replacement transmission, and drive shaft).

 

Ok thanks for the details.

One more question why does the sound completely disappear when going up hill. Is that indicative of anything else?

Also, I did have a couple random clunks when shifting into D three days ago. Assume those are the joints engaging (and making noise from failure).

Noise only started two days ago and havent really driven much, so I'll keep my fingers crossed til monday.

Nothing visible with a flashlight, but will check in the morning.

 

With the added load of going uphill the double cardon will bind up and there will be little to no slack on the joint, however the more stress it undergo's the greater the risk for failure.
Time to get the Schwinn back out of the shed and ride that until your truck is fixed.

 

Sound changes as shaft flexes with angle of truck. The unknowns are how many more revolutions the shaft has left before it sacarafices itself and perhaps the transmission to appease the Rover gods; and if the Mark 1 logic cpu between your ears has felt the substantial tug on the wallet. We are not making this up. Park the truck.

 

Don't go past checking to make sure each joint has a grease fitting, you will just be wasting your time.
If you are mechanical, send me your e-mail address and I will send a PDF on how to rebuild it and the parts required including part numbers.
If you are over 100,000 miles then replace all 4 joints and grease them at every oil change along with both slip shafts at least once a year.

 

UPDATE:

Fixed the chirp. Double U joint as suggested by the noble wizards on this forum. Thank you for the information. I had an outstanding local mechanic with appropriate tools (a vice made specifically to remove the u-joints) help me perform the task. Took two hrs total start to finish, probably would only take one hour the second time around. Very easy to access.

Anyway, the bearing caps had exploded at two points, leaving the stock bearing seals free to rattle around the exposed joint pegs. One of the bearing caps' mangled remains was literally rusted inside the yoke. I had to chisel it out.

A FEW THINGS FOR PEOPLE DOING THIS REPAIR NOT MENTIONED IN THE TUTORIAL.

1) You want to get all four wheels off the ground to remove the propshaft. A few of the upper bolts are hard to get two, so you need to throw the truck in neutral to manually rotate the shaft to access them.

2) Make sure to really whack or compress the new replacement bearing caps completely through the yoke holes, pushing them completely so that the the little C-clips can snap back into their indents on the yokes. I had to see-saw one of the joints and grind down one of the c-clips slightly to get it to seat. I used PDQ replacements, which have a tapered end and were a fraction longer than the the stock ones on the double cardan side.

The joints were $12 a piece and "made in the USA" for a grand total of $40 in parts after taxes (replaced the 3 on the front shaft). The back joint was in much better shape and will be a future mod.

3) The centering bearing was virtually as-new. If you look at the mechanics of the double joint, it appears to not take a lot of stress compared to the u-joints. It was very clean and lubricated as-is.

Thanks to everyone for saving me $1500 bucks!

Lastly, what an f-ing joke of a design!