A CBS News investigation has learned Ford may be closer to a major recall due to possible carbon monoxide leaks in Explorers, which could affect police departments across the country. Police departments say fumes are seeping into the SUVs and sickening officers, and federal safety regulators have logged thousands of complaints on the best-selling police interceptor.

In Montgomery County, Maryland, where crews are inspecting all 108 of the county's Explorers, they're finding Explorer after Explorer with cracked exhaust manifolds, the part that carries exhaust from the engine to the tailpipe, reports CBS News correspondent Kris Van Cleave.

Mechanics in Montgomery County like David Dise, director of the county's department of general services, are finding cracked manifolds in their Explorers so often that he believes the problem could be affecting 80 percent of the fleet. Most are police cruisers.

"We believe this is a manufacturer's defect," Dise said.

The exhaust manifold collects gases from an engine's cylinders. A crack could release carbon monoxide into the engine bay and through the vents of a vehicle's cabin.



"If you're running your air conditioning or your vent system, that's the air that's coming through the engine compartment. So you're sucking carbon monoxide into the cabin if you have that kind of a leak," Dise said.

While Ford engineers are not convinced the cracked manifolds are causing the exhaust complaints, the cracks are common enough to prompt Ford to actively consider a potentially costly recall. There are an estimated 135,000 Explorer police cruisers on the road today.

Police departments in more than a dozen states have raised concerns about possible carbon monoxide leaks. Ford has declined multiple requests for an interview, but did release a video statement.

"There's nothing that we take more seriously than providing you with the safest, most reliable vehicles to support your life saving work," said Hau Thai-Tang, Ford product development and purchasing executive vice president.

In February, we reported on a frightening 2015 crash in California. The police officer driving passed out. He believes it was carbon monoxide and is now suing Ford.

Following more than 2,700 complaints, federal regulators last week expanded the investigation to cover model years 2011 to 2017, citing "preliminary testing that suggests…CO levels may be elevated in certain driving scenarios."

"They live in these cruisers for, you know, eight hours at a time, maybe longer," Auburn fire department Capt. Shawn Steele said.

In Auburn, Massachusetts, a third of the town's cruisers are out of service. The local chiefs of police association there tells CBS News at least 15 police agencies in that state alone have "sidelined" Ford Explorers and are "awaiting a solution from Ford," adding "the concern among Massachusetts police chiefs is exceptionally high."

Less than a week ago, police in Austin, Texas pulled more than 400 Explorers out of service because 18 officers were found to have carbon monoxide in their blood. Now Galveston police have parked their Explorers as a precaution, which Ford is working to put back in service.

We've learned departments across the country are inspecting their Explorers and rushing to install carbon monoxide detectors. Ford has not made a final decision on a recall.

After the broadcast of this report, Ford issued this statement: "All of our testing to date has not shown cracked manifolds contributing to the carbon monoxide levels in Police Interceptor Utilities. We continue to investigate." Late Friday, Ford issued another statement, saying, "Our decisions are driven by the data available. When the data indicates a safety recall is needed, we move quickly on behalf of our customers."