The contact owns a 2008 Hummer H3. The contact stated that the vehicle intermittently failed to start up without warning. The contact stated that after waiting ten minutes the vehicle started. The contact stated that recently the failure had become more frequent. The contact had taken the vehicle to a dealer however, the mechanic was unable to determine the cause of the failure. The manufacturer was not notified of the failure. The vehicle was not repaired. The failure mileage was approximately 1,000.

- Evergreen, CO, USA

The contact owns a 2008 Hummer H3. The contact stated that while driving at various speeds, an abnormal knocking sound was coming from the engine. The check engine warning light was illuminated. The contact stated that the failure worsened while driving at highway speeds. The contact called the dealer and the manufacturer and notified them about the failure. The contact was informed by both that there were no recalls on the vehicle. The vehicle was not repaired. The failure mileage was unknown.

- Kansas City, MO, USA

The antilock safety is preventing me from starting my vehicle. When it does start, and I go to an intersection to turn the truck will then stall out. It can cause a wreck. It is a huge safety issue, time consuming, and money consuming when I have to wait 10 minutes to try to start my truck, or it doesn't start, I have to replace it for $450+ which I don't have to replace the ignition switch and it's dangerous because if it does let it start I have to be careful because it will stall out on any given second causing a catastrophe!!! there are multiple people with the same issues on their vehicles. GM should be responsible to do a recall and fix this problem.

- Fort Morgan, CO, USA

Radiator has a 8 inch horizontal hair line crack that lets the coolant leak. The crack is on top right corner( drivers side). The radiator top is made from plastic that is prone to cracking due to framework bumping into it causing strain on radiator top which after time causes the top right corner to establish a hairline crack and cause the coolant to leak. Many Hummer H3 vehicles owners have complained about this issue of having hairline cracks in top right corner. Hummer has replaced several Hummer owners radiators at no cost, due to a design flaw that the top right radiator bumps into the framework causing stress on it and cracking. GM has updated the radiator to accommodate for this issue, but has not showed interest in saying that this is a big issue. Why would they allow this to happen to thousands of Hummer H3 owners if they know this is a design flaw which they are aware of. My Hummer H3 only has 24,400 miles in it and street driven only how could this happen to soon.I had it checked by my local GM dealer and they stated that you're not the only one complaining about this and to contact GM regarding this issue.

- Cathedral City, CA, USA

The engine completely shut off while driving on a major highway. The steering wheel locked up and the car came to a stop. Luckily, each time this occurred, I was able to pull over to the shoulder. There were no error lights that came up on both occasions of this happening. The battery continue to die, even after being replaced three times in 6 months!

- Conshohocken, PA, USA

Cylinder 5 head is bad

- Everett, WA, USA

The security lock system on my Hummer H3 intermittently flashes during start causing the vehicle to not crank. Normally I have to wait 10 to 20 minutes for the system to reset itself and she starts right up, but today it's been 8 hours. Finally I had to call for a tow to the GM dealership. We got lucky today. At 10am my wife thought she was going into labor, we get to the truck and no start. Just a flashing security lock symbol flashing at me. Ended up using her car. This is definitely a safety concern, what if her water had broke or my son was needing medical attention. I know GM knows of this defect because I have read thousands of complaints about this exact problem online. They will not fix it unless made to.

- Orlando, FL, USA

Upper rail rubbed against the plastic tank on the radiator, creating a crease that fractured, spraying radiator fluid all over the engine compartment. Radiator had to be replaced. Tech advised that the design of the vehicle was faulty because the rail was installed too close to the radiator. He shimmed it to prevent it from happening it again.

- Altoona, PA, USA

The contact owns a 2008 Hummer H3. While driving 45 mph, the temperature gauge displayed that the vehicle's temperature was very high. The contact merged to the side of the road and poured antifreeze into the vehicle. The failure recurred numerous times. The vehicle was taken to a dealer. The technician diagnosed that the radiator had fractured and needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was 74,000. The VIN was unavailable....updated 08/10/15

- Matawan, NJ, USA

While driving I noticed heavy smell of antifreeze.. I took to local shop and we noticed antifreeze all over engine. Radiator had crack on top. After research I see multiple complaints online with other Hummer owners same issue. Had to replace radiator. Mechanic said ther radiator rubs and bounces against the frame causing crack.

- Plainview, NY, USA

Without any warning, the engine began to misfire and stall out after starting from a green light. It only lasted about 10 seconds. After this, the engine quit misfiring and began to have an audible whine come from under the gear shifter. This was subsequently diagnosed by electronic means as an intermittent misfire and accelerator pedal position sensor. After examination by a mechanic, in the lower portion of the engine a bolt holding in place one of the balancers worked itself free. The entire bolt was displaced from its original location and the threads were protruding out of the plate behind the flywheel in the area of the rear main seal causing a significant loss in oil. Upon further inspection after the engine was removed, multiple components appeared damaged as a result of the bolt getting stuck in one of the internal chains. The whining noise was a result of the chain rubbing against the remains of the bolt that was lodged and partially expelled from the lower rear of the motor. Finally, to be clear, this incident appears to be the result of a bolt being improperly torqued, machined or the balancer being improperly machined and matched for the bolt. Again, the entire bolt (including threads) was free from the component it was installed in.

- Troy, OH, USA

Radiator end tank ruptured releasing coolant on everything under the hood and getting on the windshield. Research of this finds that there is a defect in the design of the factory radiator which GM refuses to take action on. Had this happened at higher speeds, this could have been a much worse situation.

- Louisville, KY, USA

The radiator had a crack in it when we bought the HH3, in 6-2011 which was replaced with a new factory radiator. It is now March 0F 2013 and we have another crack in the radiator. We contacted" savvy" Goodyear in long beach, New York who replaced the first one and they said it is not covered. Really does a radiator only last 2 years. They indicated that GMC would not cover the replacement. I see that this has happened to several vehicles shouldn't there be a recall?

- Winchester, VA, USA

I bought a 2008 Hummer H3 four months ago at 49,956 miles, when last week I noticed I had a bad coolant leak causing the fluids to remain on the top of the engine, the fan shroud, etc. Had it towed back to the dealership where I bought it from because its a 48 miles drive and didn't want to take the chance of anything overheating. Took it in on Friday morning got it back Monday afternoon when I was told the radiator was cracked. After looking on the internet seems like everyone seems to be having this problem. The mileage when the dealership received it on Friday was 52,547.

- Piqua, OH, USA

Radiator has cracked due to manufactures defect.

- Sullivan, MO, USA