I have a 2004 Disco II. Whenever I drive my truck and take my foot off the accelerator I hear a high pitch whining noise.

When I step on the accelerator and maintain pressure, the noise goes away. Sometimes I hear it when idling at a stop.

Anyone else have this problem? I love my Disco but she is slowly bleeding me dry...lol.

 

What have you checked so far? Have you had the front drive shaft rebuilt or replaced, how often do you grease the u-joints, have you opened the hood and reved up the engine to listen for a noise, could be a bad bearing in one of the belt driven pulleys.

 

Could also be a vacuum leak, when foot off pedal vac increases sharply. Finding it in that nest of vipers under the hood is a slow process. Some squirt small quantities of carb cleaner around hoses, intake gaskets, etc. while listening for a change in idle. Sometimes listening thru a length of rubber hose will help isolate. Obstructing the air intake will make it scream louder, but it you close it off 100% the engine vacuum can damage some seals.

Hearing it inside the truck with windows up makes me think it would not be a vac leak, Disco Mike has covered the more costly items that do tend to be louder.

 

@Disco Mike - To date I have replaced one head gasket, waterpump, and most recently the serpentine belt (as it looked worn and thought it might be the belt). It wasn't.

I haven't listened for the whine with the hood up yet to try and isolate, nor have I lubed the u-joints recently.

@Savannah Buzz, I'll check that area too.

I'll get back with you guys after I do some more digging. Thanks

 

That is probably your transfer case. Whines when it is braking the engine.

You go say from 70 MPH to 40 - let the gas off and there is that whine.
Not a big whine, but it is there.

To feel better, pull out the transfer case fill screw and make sure there is synthetic 90W oil in there.
If the transfer case has oil, then don't worry about the whine.

 

yep, if the whine is center mounted. But at idle? A yardstick held to your ear and touched to the case or case shifter might help isolate the noise. Check oil level in TC, and with lotza miles, consider 85W140 fluid. I added some Lubegard to mine and it quieted it more. LUBEGARD Gear Fluid Supplement

 

Discotwo, I have a similar whine on my new longblock. I really think its a vacuum leak, but I haven't been able to find the source. Could even be the lower intake (you removed yours as well to do the HG job, right?). I'll let you know if I figure anything out.