(CBS NEWS) -- 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.

MORE: Read/watch the full story at CBSNEWS.com