I have noticed over the last week that early mornings I am hearing an irritating chirping sound, like a bearing is going on a tensioner? It does it doing it early and only since the weather here in Denver has dropped below freezing at night.
There is no chirp at idle, in neutral, and pressing the gas...reving the engine.
As I drive down the street and reach 15-20mph the chirp begins.
If I hit the gas hard, it goes away.
If I put the truck in neutral and let it coast, the sound still stays until the speed is reduced.
Once I drive the truck about a mile, the sound is gone for the rest of the day...all seems good
Applying the brake does NOT make the sound go away... leading to my question.

I have noticed in cold weather, my brake master cylinder leaks brake fluid...
from the bottom of the reservoir. Only when it is cold. Could the brake system be loosing some pressure and dragging a pad on the rotor?, thus causing this chirp

Was planning on replacing the leaking part for sure. Is it worth buying the repair kit for the master cylinder, or just get a new unit installed.

 

Well, this may be dangerous but..
When you are going in neutral at 25 to 30MPH and the chirp is there.

What happens if you turn off the engine and you are coasting???

Of course, your steering goes stiff and you only have a few pumps in the brake left.
But, if the chirp then goes off - engine related or transmission as those are spinning when the engine is running.

You need to be practiced on starting up the rover or stopping completely and then restarting it.

To me a chirp is a sound like a bird.
Comes and then is gone.

This sound of yours seems like a high pitched squeal?

I think you did a good job of diagnosing it by going to neutral.

 

I just replaced both idler pulleys on my 99. I rebuilt the 80mm with a new bearing and put and entirely new 70mm on. My 70mm was still the plastic one and I was getting a hi pitched grinding sound that was borderlining on a "squeal" or "chirp". I think it has something to do with the plastic. neither of my pulleys appeared to be moving side to side. but I cured a specific sound when I replaced each pulley. I used a piece of clear waterline, and put an ear plug in one ear to do the stethoscope method. that will be har for you a 25 mph...lol.. but I would look pretty hard at your passenger side idler pulley. but honestly it could be any one of your pulleys.

 

"Chirp" is frequently reported by those who have a front prop shaft let go and try to kill the tranny. Since you don't have it at idle, pulleys may be off the hook. Looking at the front shaft would be a good idea. The factory sealed end does not have grease fittings, there is a rebuild write up in the tech area. $100 repair vs $7000 for a dealer transmission.

 

definately check the drive shaft, it appears that it only makes noise when moving that would not be a engine problem but a drive line problem

 

I had purchased this Discovery with 63,000 and had the driveshaft replaced with a serviceable shaft. Over the last 60,000 miles I had religiously greased the shaft, but I guess it now has 60,000 miles on the new one.
Thanks for the input...I will make time in the next day or two to go under and check it out. What should I look for once I am under the truck?. Will I be able to notice any play in it? cracks etc?
(When I get a chance I may slide under the truck and get some reference photos.)

Any good places in Denver to have my shaft rebuilt?...at a reasonable cost if I need it done?

 

I second the propshaft. Specifically the centering ball. If the noise is still there while coasting down the road in neutral w/ the engine off its the propshaft. Unleass your a machinest, save yourself the headache of trying to rebuild this thing yourself. Google Great Basin Rovers talk to Bill and pick up one of his shafts. I did.

 

I would also be checking out the drive shaft. If you have the cdl on yours you ciuld pull the front shaft lock in the cdl and see if the noise goes away.

 

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