Stopped do to heavy traffic and started smelling exhaust in cab. Pulled off on next exist opened hood and drivers side of engine was smoking. Coughing and lung discomfort. Found some shade to let truck cool. Noticed black color on rear of exhaust manifold, looked closer and missing bolt in same area of manifold. Looking online lots of complaints of same problem but no recalls. Should be emissions recall and safety recall in my case.

- North Ogden, UT, USA

Stopped do to heavy traffic and started smelling exhaust in cab. Pulled off on next exist opened hood and drivers side of engine was smoking. Coughing and lung discomfort. Found some shade to let truck cool. Noticed black color on rear of exhaust manifold, looked closer and missing bolt in same area of manifold. Looking online lots of complaints of same problem but no recalls. Should be emissions recall and safety recall in my case.

- North Ogden , UT, USA

This truck is equipped with the 6.0L vortec V8 engine and has developed an exhaust leak on both sides of the engine at the manifold gaskets! the leak is from the ports where the bolts securing manifold to cylinder head are broken! GM is well aware of this issue, does not want to recall the issue or warranty the repairs. There are thousands of complaints from owners of GM vehicles with V8 engines including the 4.8L, 5.3L, 6.0L engines. This is a problem in many of ways, most importantly that toxic exhaust fumes are emitting from under the hood and can enter the cab of the vehicles! inspection laws require that exhaust fumes exit the vehicle behind the rear wheel! the other problems include the fact that this leak will affect readings taken from the upstream oxygen sensors and can therefore cause check engine lights for catalytic converter deficiencies to system lean conditions. Also having an exhaust leak will fail safety inspections and emissions testing. GM is violating epa laws by allowing this to go on! this particular vehicle is past due for inspection and emissions as we are a Pennsylvania resident and I cannot afford to have this fixed at a dealer!

- Stewartstown, PA, USA

Exhaust manifold bolts breaking leaving studs in the heads, heating up engine compartments, releases carbon monoxide, affects O2 sensor and catalytic converter. Will not pass emissions in some states. GM not standing behind this 1999-2008 issue. It is a safety issue and is expensive to fix. GM mechanics denying any such issues. Please check- in to this. Our whole fleet and our personal trucks affected by this.

- West Lebanon, IN, USA

Exhaust manifold bolts breaking off leaving studs in the heads heating up engine compartment, releases carbon monoxide, affects O2 sensor and catalytic converter, will not pass emissions in some states. GM not standing behind this 1999-2008 issue. It is a safety issue and is very expensive for us to fix. GM mechanics say they have not heard of this issue. Please check in to this.

- West Lebanon, IN, USA

This is the second time it has happend, my exhaust manifold bolt breaks.

- Otisfield, ME, USA

In June, 2011, I began noticing my antifreeze levels were dropping slightly. There were no noticeable leaks of antifreeze anywhere. I attributed it to evaporation & added coolant. Over time the truck started using more & more antifreeze. A friend of mine noticed a puff of white smoke coming from the tailpipe. At the time I didn't really think anything of it. Last week while driving home from work after finishing up a "B" trick job (11pm), I noticed a knocking sound coming from the engine. It smoothed out after a few miles of driving it. The next day it happened again ( I work 26 miles from home) again it smoothed out & I was just grateful I got home safely that night. By this time I knew there were some serious issues & decided not to drive it again. I began researching the issue on line & found others that were experiencing identical symptoms. Turns out the problem lies with the cylinder heads in the engine manufactured for GM by castech. According to other people & by gms own admission, a faulty, weak material was used to build the cylinder heads. Over time the material wears away causing porous cracks & the antifreeze seeps into the oil system polluting it, causing significant damage to the engine. (by this time most extended warranties are up). The antifreeze mixes with the oil & is emitted out of the tailpipe as exhaust. This is why no traces of antifreeze were found & the reason for the white puff of smoke. GM issued a bulletin #06-06-01-019B in June 2007 informing repair technicians on where to look for the damage. Through other peoples experiences, I am finding the engines were ruined in 90% of the cases & GM claims no responsibility. In my case I am driving a friend's vehicle waiting on word from my mechanic as to my options. These repairs are costly. Up to $5000!! this is not from normal wear & tear this is a manufacturing defect & I feel a recall should be issued.

- Leroy, NY, USA

The contact owns a 2005 Chevrolet Silverado 2500. The contact stated that exhaust fumes were emitted from the vehicle in an unusual fashion and entered into the cabin of the vehicle. The vehicle was taken to an authorized dealer where the contact was informed that the engine manifold was warped because the bolts were corroded. The vehicle was repaired. The failure recurred approximately two years later. The vehicle was taken back to the dealer and was repaired a second time for the same failure. The manufacturer was made aware of the failure and offered no assistance. The failure mileage was 87,000. Updated 02/14/12 the consumer stated he corrected the problem by using stage 8 bolts and headers. Updated 03/16/12

- Natick, MA, USA

The bolts that hold the exhaust manifolds to the cylinder heads are braking off for no reason causing an exhaust leak.

- East Bernard, TX, USA

My 2005 Chevrolet Silverado 2500hd had broken exhaust manifold bolts. Repaired at 87,000 miles. Went to dealership today because of exhaust leak and was told there are more broken bolts at 136,000. Obviously there is a defect. Unsafe/raw exhaust leaking into air and cab.

- Natick, MA, USA

The contact owns a 2005 Chevrolet Silverado. The contact stated the vehicle was abnormally losing coolant every three weeks. The vehicle was taken to a local repair facility where the mechanic was unable to determine the source of the leak. The vehicle was not repaired. Neither the dealer nor the manufacturer was contacted in regards to the failure. The contact was concerned with the possibility of the vehicle overheating as he located numerous complaints online regarding the failure in his year, make and model but no recalls. The failure mileage was 80,000.

- Meriden, CT, USA

I took my 2005 Chevrolet Silverado pick up in for a exhaust leak. The manifold bolts rotted away. 3 bolts holding right and left exhaust manifolds in place. Vary very unsafe, one good bump in the road and it would drop. Vehicles with less than 30,000 miles have the same problem. GM knows about the problem and should have contacted it's customers. Vary dangerous. Fire, accident or exhaust fumes. Not good at all!!

- Fairfield, CT, USA

The engine oil cooler lines and the transmission cooler lines leak at the crimp where the rubber hose and metal lines connect. After doing research online about this I have discovered it is a very common problem. Some people have replaced these lines multiple times only to have them leak a short while later. For those of us whose vehicles are out of warranty this can be very costly. I would also think that transmission fluid and motor oil contacting hot surfaces like an exhaust pose a fire hazard. At the very least the leaking oil is an environmental hazard. I have purchased oil cooler lines and am replacing them tomorrow but I am having trouble finding transmission lines.

- Westland, MI, USA

Vehicle quits running anytime, brakes and steering "hard", dead battery like symptom and will not start or restart after quitting.

- Arlington, VA, USA

Vehicle quits running and may restart after 10 minutes or may not. It shuts off at any speed and at red lights. When on a hill it will roll back into whatever is behind. This vehicle has been to the dealer 6 times and they can find nothing wrong. Sometimes there is power to the dash and lights, other times the dash goes dark as if there was no power at all.

- Arlington, VA, USA

: the contact stated the vehicle infrequently stalled while traveling 70 mph. The service dealer could not duplicate the issue. This has occurred since April 2005 and has begun to occur more frequently.

- Venice, FL, USA

: the contact stated the vehicle stalls at any speed without warning. The vehicle was taken to the dealership several times. The level sensor, fuel injection wiring harness, the direct fuel injection driver, the fuel tank, and the fuel tank module have been replaced. The sender pump assembly was replaced twice. After the last replacement the check engine light illuminated and the dealer could not determine the cause of the problem.

- Jacksonville, AR, USA

Truck has 14000 miles, it has constant over heating problems while towing my 8K travel trailer. I have talked with the Chevrolet dealer about it, they told me that they were aware of the problem but at this time have no fix. I call stupid because I heard online that the 06 models have revised cooling systems and a larger turbo charger. My belief is the fix is to much $$ and they will only take care of the few people that tow and have issues. I have notice a lot of information on the net about 04.5 and 05 lly duramax truck that tow over 10000 have this issue but my travel trailer fully loaded only weighs under 9K. The major down side is the trucks inability to maintain the speed limit due to the overheating water temperature and the power loss formed a cooling fan that runs hyperspeeds no stop when towing. My towing has been done at low outside temperatures ranging for 75 to 85 degrees outside. This truck is not performing as advertised or supposed to be designed for.

- Yorktown, VA, USA