2000 Disco II. So here about the past few weeks I've noticed this noise coming from the truck. It happens a idle and while going down the road. It starts and stops at random, although never more than 30 seconds between. It sounds high pitch, and like a whine...It almost sounds electronic, but I'm not sure. Radio shut off I still hear the noise. The truck runs fine except for the 3 amigos popping up every now and then. Also it sounds like it's comming from the front of the truck. What do you guys think it could be?

 

A vacuum leak maybe?

 

Probably your secondary air. Next time it happens pop the hood and see where the noise is coming from. The SAI is on the passenger side of right on the firewall. It sounds like a jet plane and usually comers on right when you start the truck.

 

Better yet, instead of us guessing all day, tell us what you have checked so far and be specific.

 

Well..I popped the hood today and tried to find exactly where it is coming from. It is somewhere at the rear of the engine and seems to be on the drivers side. I don't have secondary air injection. I really can't in pinpoint where the noise is coming from i can just get close. There is a shiny canister in the center of a "T" of black hoses at the rear of the engine(right on top). It seems to be coming from that area but, upon grabbing it and pushing and pulling on it durring the sound I hear no change in sound quality.

 

That is your idle solenoid, sounds like you have a vacuum leak. Check all your upper IM bolts as they can come loose and the connections to all the hoses in the area of the IM and plenum.

 

I once had very similar issue in my 01 DII. Next time it is making the noise try turning off the HVAC and see if it goes away. I figured the bearings in the fan were going bad and when I came across another DII at the junkyard I pulled the fan to swap it. Well, the harnesse didn't match but I was able to clean all of the carbon dust from the brushes on the fan motor out of my current motor and the noise went away.

 

nope. Ive tried turning off the HVAC when its happening. No change. The noise now goes away when accelerating, but returns when I let off the gas. And it's there when idleing. Ive been listening to it trying to find the exact source and Ive got it really close. I dont think its the idle solenide, but there is a black(smaller) but similar cannister just under the idle solenoid. I think its comming from that or something under it but i cant see anything under it. Unless its the intake manifold gasket and just happens to be leaking right there. But if its the IM gasket why does the sound go away when I press the gas?

 

Remove the serpentine belt, idle and rev the engine, does it still do it?

 

so I stop by my mechanic's shop and let him listen. He first says its a vacuum leak. He then takes a can carb cleaner and starts spraying it on parts of the engine. He sprays up in under the valve cover on the driver side and the noise stops immediately. He says it's a leaking intake manifold gasket. Says the labor to replace it is $150.00. How does this sound to you guys?