There are 13 owner-reported engine complaints for the 2008 Hummer H3in NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
exhaust leaking in cab of the car .Exhaust bolts broke or manifold cracked problem i heard about on line .on a long trip could make you passout with the fumes .please check it out .on most inline 5 cyclinder engines GM makes .Thank you [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
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.
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.
CYLINDER 5 HEAD IS BAD
TL* THE CONTACT OWNS A 2008 HUMMER H3. WHEN THE VEHICLE WAS TAKEN TO BE SERVICED FOR NHTSA CAMPAIGN NUMBER: 15V421000 (VISIBILITY), THE TECHNICIAN DISCOVERED THAT TWO BOLTS LOCATED ON THE EXHAUST MANIFOLD WERE FRACTURED. AS A RESULT, CARBON MONOXIDE WAS LEAKING INSIDE THE VEHICLE. THE VEHICLE WAS NOT REPAIRED. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE. THE FAILURE MILEAGE WAS 54,000.
TL* 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*BF
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.
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. *TR
MY RADIATOR CRACKED AND I WAS TOLD AND HAVE READ THIS IS A VERY COMMON PROBLEM WITH THE H3 HUMMERS AND CHEVY COLORADO . *TR
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. *TR
RADIATOR HAS CRACKED DUE TO MANUFACTURES DEFECT. *TR
CRACK IN THE RADIATOR, HAD IT REPLACED AT A INDEPENDENT SHOP NOT KNOWING THAT THIS IS AN ON GOING PROBLEM WITH THIS MODAL HUMMER. DEFINATLY A FLAW SOMEWHERE ON GMS PART. *TR
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? *TR
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 26, 2026