Reports of nine fires prompted the automaker to recall more than 89,000 of the SUVS and midsize cars in the U.S. and Canada last month. No injuries were reported and only models with 1.6-liter turbocharged engines were recalled.
Ford offered free loaner cars until it figured out what caused the fires.
It was the fourth recall in four months for the new Escape, a top seller in the competitive market for small SUVs. The 2013 version has had problems with coolant leaks, cracked fuel lines and carpet padding since it started selling this spring. The Fusion has been recalled twice.
The overheating problem occurs when coolant doesn't flow through the radiator to be cooled, Ford Motor Co. Product Development Chief Raj Nair said Monday. Engineers found that a valve that controls the flow of coolant to the radiator wasn't opening at the right time.
Coolant could flow into the engine, get trapped and overheat. That could cause a gasket to blow, spilling coolant or oil onto hot exhaust parts and causing fires.
A software change in the computer that controls the valve will solve the problem, Nair said.
The software updates should be available at dealers early next week, Nair said. Because the problem is so rare, the cars and SUVs are safe to drive. But if drivers see a warning light about overheating, they should pull to the side of the road, shut down the engine and call their dealers, Nair said.
About 73,000 Escapes and 16,000 Fusions have been recalled.
Even though Ford urged people to take their cars to dealers and get the loaners, only about 17,000 Escape and Fusion owners followed the advice, Ford said.
Ford offers the 1.6-liter engine in the Fiesta subcompact and on several models in Europe, but the cooling system controls are different and those vehicles don't have the problem, Ford said.
Safety advocates say that more than three recalls in a car's first year are a sign of quality problems. But Nair said all of the recalls are isolated incidents and don't mean the vehicles have reliability problems.
"We look at it as individual issues and determine the right thing to protect the customer," he said. "When a potential issue is identified, we act promptly on behalf of our customers."