There are 10 owner-reported engine complaints for the 2014 Mercedes-Benz GL-Classin NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
On this Engine 166 model, I experience noise when Idling and when driving, coming from Engine with no code to indicate what is the problem of the car. This create the heat of the Engine to go up than normal and make the fan to run at high speed. When I call dealer, they told me its common problem on these Engine 166, and I need new Engine. I wanted to get second opinion from different Dealership and I got same answer, its common problems and I need new Engine or to Rebuild. I went online and I ask few people with same car Make, model and year, and the have same problems. My concern is only Dealer knows what is the issue but they don't want to inform Consumer what is the problem, instead they tell Consumer to replace the Engine, We don't how bad it is for safety. The problems it cannot be diagnosed because it doesn't produce any codes to indicate the problem. The noise continue until you turn off the Engine
The contact owns a 2014 Mercedes-Benz GL550. The contact stated that the check engine warning light was illuminated. The vehicle was taken to the dealer, where it was diagnosed with leaky exhaust valves. The dealer determined that the exhaust valves needed to be replaced. The vehicle was taken to an independent mechanic, where a similar assessment was made. The vehicle was not repaired. The manufacturer was notified of the failure and informed the contact that the vehicle was not covered under TSB Number: 10233794. The manufacturer referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 104,000.
Leaky exhaust valves
It has makes sound noise and timing chain tension is made very poor not safety , also warming blibd spot frozen not working, display electric poor damage byself tomve fix timing dealer wants 15,000$ to be fix more then value of the suv
The contact owns a 2014 Mercedes-Benz GL450. The contact stated that while driving 65 MPH, the vehicle stalled. The check engine warning light was illuminated. The vehicle was able to be driven to the residence. The vehicle was towed to the dealer, where it was diagnosed and determined that the engine needed to be replaced. The vehicle was then towed to an independent mechanic, who also determined that the engine needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and a case was opened. The failure mileage was approximately 108,000.
Car got a check engine for failed turbochargers at 71000 miles. Mercedes refused to acknowledge and get the problem addressed.
Tapping noise developed in the engine, after dealership inspection using borescope, scored cylinder walls were found, resulting to engine replacement. Please see: Lena Jamil, et al. v. Mercedes-Benz USA, LLC (Case No: 2:22-cv-08130-FLA-AFM)
There were numerous Engine Oil Leak Recalls by Mercedes-Benz. There was a recent recalls announced in 2023, however, my vehicle 2014 GL450 with now about 50K miles, was not included in the list. Since there have been engine oil leaks problem reported and recalls, I'd like to report my car engine oil leaks problem too. It seems that the engine oil leaks problem is a "design" issue and across many car models and years made by Mercedes-Benz. With that said, it make safety sense to have the recalls extended to those cars with engine oil leaks problem reported. Below is information from dealer diagnostic report on engine oil leaks problem, "Valve Cover Re-seal: FRONT TIMING COVERS RECOMMENDED RESEAL SIPING OIL BOTH SIDES Item Description During a vale cover reseal, the valve cover is scraped and cleaned of any old residue, before a layer of silicone sealant is applied to the cover and then reattached to the head of the engine. Reason If not resealed or replaced, the valve cover will leak oil resulting in a burning smell coming from the vehicle’s engine. A loss of oil over time can result in harmful damage of the engine's internal components."
The contact owns a 2014 Mercedes-Benz GL350. The contact stated that while inspecting the vehicle, there was oil leaking underneath the vehicle. Additionally, the check engine warning light was illuminated while operating the vehicle. The vehicle was taken to the local mechanic who diagnosed the vehicle and determined that the oil cooler seals were faulty and needed to be replaced. The seals were replaced, and the vehicle was repaired. The vehicle was later taken to the local dealer for transmission failure. The manufacturer was notified of the failure. The failure mileage was 140,000.
HAVE A MERCEDES GL 350 WITH ONLY 63000 MILES, HAS MADE A SMALL RATTLE SOUND WHEN FIRST PURCHASED THAT I RELATED TO BEING DIESEL, RATTLE HAS GOTTEN WORSE, TOOK IN TO A MECHANIC WHO STATED TIMING CHAIN, I CALLED MY MERCEDES LOCAL DEALERSHIP AND SERVICE MANAGER STATED HE SPOKE WITH AUTO TECHNICIAN WHO "LAUGHED" WHEN HE HAD TOLD HIM MY CONCERN FOR THE TIMING CHAIN AS THE TECH SAID THIS DOESN'T HAPPEN UNTIL VEHICLES ARE VERY HIGH IN MILES LIKE 200000. THEY EXAMINED MY VEHICLE AND THEN STATED IN FACT IT WAS THE TIMING CHAIN AND QUOTED ME 75000. UPON FURTHER RESEARCH THERE HAS BEEN AN ISSUE WITH OTHERS ON THE INTERNET WITH THE GL 350 2014 SPECIFICALLY NEEDING TIMING CHAIN REPLACEMENT WHEN UNDER LOW MILES. CAR RATTLES WHEN STARTED, WORSE WHEN COLD, CONFIRMED TIMING CHAIN BY LOCAL MERCEDES DEALERSHIP.
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 25, 2026