Weird Noises on O2' Denali

I just purchased a 2002 Yukon Denali 2 months ago. I have been hearing weird sounds come from everywhere. Can anyone please help me figure these out? 1. There is one loud ping coming from the muffler/exhaust area. I have heard if you put a heat sheild around the muffler or replace the entire thing it will fix it. Is this correct? 2. There is a whinig/rubbing noise when you accelerate at low speeds. Could it be the front axle? 3. There is a noise that sound like detonation when you accelerate at any speeds, the dealer says it is normal. I know better they have already done the thorttle body cleaning and induction service and it did not help, any suggestions? 4. There is an intermittent clunking noise coming from the engine area it only does this maybe once a week, it sound like the transmission is falling out but dealer says transmission is perfect, what could it be? Also my rear air is blowing out warm. Could that sound be coming from the ac compressor? Please help these noises are really bothering me.

Your GM dealer should check your exhaust. I had mine replaced under warranty with 73,000 miles on my truck. GM has a new 8 year/80,000 mile emmissions warranty.

I actually had the muffler removed and found that their was a broken beffle in it. That fixed the problem with the exhaust ping, now I just need to fix the other problems. Thank you for your response.

The noises in the exhaust, is the ping constant or is it every couple of minutes once the truck is warmed up? Because I believe I have a similar problem and can't figure it out.

It is one ping, every now and then. I found out what it was though. My muffler had a broken baffle in it, beleive it or not. With all the problems I have had with the AWD system I am trading this Denali in. I can't stand the noises any more. I am probably gonna get a Hummer.

It is one ping, every now and then. I found out what it was though. My muffler had a broken baffle in it, beleive it or not. With all the problems I have had with the AWD system I am trading this Denali in. I can't stand the noises any more. I am probably gonna get a Hummer.


I bought a used 2002 Yukon Denali recently and took the vehicle into the dealership for the whining noise coming from the front end when lightly accelerating. They told me this was normal and all the research I've done tells me that is a common issue with GM's AWD system.

I bought a used 2002 Yukon Denali recently and took the vehicle into the dealership for the whining noise coming from the front end when lightly accelerating. They told me this was normal and all the research I've done tells me that is a common issue with GM's AWD system.

Here is a service bulletin I think applies:

Here is the Bulletin...

Whine Noise From Front Axle (Diagnose and Replace Front Propeller Shaft with a Tuned Internally Dampened Front Propeller Shaft) #03-04-17-005 - (03/13/2003)
Whine Noise from Front Axle (Diagnose and Replace Front Propeller Shaft with a Tuned Internally Dampened Front Propeller Shaft)
2002-2003 Cadillac Escalade, Escalade EXT

2000-2003 GMC Yukon Denali, Yukon XL Denali

2001 GMC Sierra C3

2002-2003 GMC Sierra Denali

with AWD Transfer Case (RPO NP3 or NR3)

Condition
Some customers may comment on a slight whine noise from the front of the vehicle during light throttle conditions, typically at two vehicle speed ranges of 64-80 km/h (40-50 mph) and 112-129 km/h (70-80 mph).

Cause
"Inherent" ring and pinion gear whine.

All gear driven units, such as automotive rear axles, produce some level of noise that cannot be eliminated with conventional adjustments and repairs. "Inherent" axle noise can be described as a slight noise heard only at a certain speed on most General Motors® trucks. The presence of this noise is not indicative of a functional concern with the axle assembly. However, some customers may find that this "inherent" axle noise is unacceptable.

Correction
Replace the front propeller shaft with an internally tuned dampened shaft ONLY after diagnosis concludes that it is an "inherent" front axle noise and no physical damage or incorrect adjustment exists.

Diagnostic Information and Procedure for Front Axle Noise
Diagnostic Starting Point - Front Drive Axle (Refer to SI Document ID #696970).
Symptoms - Front Drive Axle (Refer to SI Document ID #696957).
Front Drive Axle Noises (Refer to SI Document ID #700621).
Noisy in Drive (Refer to SI Document ID #700622).
Noisy When Coasting (Refer to SI Document ID #700624).
Intermittent Noise (Refer to SI Document ID #700625).
Constant Noise (Refer to SI Document ID #700631).
Noisy on Turns (Refer to SI Document ID #700634).
Front Propeller Shaft Replacement
Raise the vehicle. Refer to Lifting and Jacking the Vehicle (SI Document ID #737171).

Important
Before disassembly, observe and accurately mark all of the driveline components relative to the propeller shaft and to the axles. These items include the following components:

The propeller shafts
The wheel drive shafts
The pinion flanges
The output shafts
Assemble all of the components in the exact relationship to each other prior to removal. Observe all published specifications and torque values and any measurements obtained prior to disassembly.

Remove the transfer case shield, if equipped.

Remove the clamp (if applicable) (4) at the transfer case (3) by prying up the exposed end of the clamp (4) with a flat-bladed tool.

Remove the bolts (6) and the yoke retainers (7) from the front axle pinion yoke (1).

Notice
When removing the propeller shaft, do not attempt to remove the shaft by pounding on the yoke ears or using a tool between the yoke and the universal joint. If the propeller shaft is removed by using such means, the injection joints may fracture and lead to premature failure of the joint.

Disconnect the propeller shaft (2) from the front axle pinion yoke (1).
Remove the propeller shaft (5) from the transfer case output shaft by sliding the propeller shaft forward.
Inspect the splines of the transfer case output shaft for a sufficient coating of lubricant. If the output shaft does not have a sufficient coating of lubricant, lubricate the shaft with lubricant, P/N 12345879 (Canadian P/N 10953511), or with an equivalent lubricant meeting GM specification 9985830.

Important
Some old driveshaft boots may only use a single clamp design. When installing the new propeller shaft, use ONLY a two clamp boot.

Install the new clamp, P/N 26064275, supplied with the new propeller shaft, P/N 15186002, into the groove of the propeller shaft boot.
Install the propeller shaft splines into the transfer case output shaft.
Install the propeller shaft to the front axle pinion yoke.
Install the yoke retainers and the bolts. Tighten
Tighten the yoke retainer bolts to 25 N·m (19 lb ft).

Install the boot onto the transfer case output shaft until the boot is attached into the groove on the output shaft.

Using the J 43218 , crimp the clamp until the dimensions that are shown are obtained.
Install the transfer case shield, if equipped.
Install the transfer case shield mounting bolts, if equipped. Tighten
Tighten the transfer case shield mounting bolts to 20 N·m (15 lb ft).

Lower the vehicle.
Parts Information
Parts are in limited quantities. DO NOT order parts for stock.

Part Number
Description
Qty

15186002
Propeller Shaft, Front