If you’ve been following the Ford Focus RS on internet forums, you might come to think that every example ever sold has developed an issue that causes it to consume coolant. The actual share of afflicted RSes is far below 100 percent, of course, but according to Autocar, Ford does indeed acknowledge that the 350-horsepower, 2.3L EcoBoost I4 in the Focus RS is prone to incurring a habit of losing coolant.
The 2.3L EcoBoost four-cylinder in other Ford models, like the Ford Mustang EcoBoost, isn’t believed to be affected. That version of the engine uses a different alloy in its cylinder block and head.
Ford is “working on a repair for all customers,” a spokesperson says. “In the meantime, if vehicles show these symptoms, customers should visit their dealer for an inspection and repair under warranty,” he says.
The issue is thought to stem from how the block expands and contracts through several heat cycles. Engines with as few as 6,000 miles appear to be distorting beyond the accepted tolerance, preventing a proper seal at the headgasket between the block and the head. This allows coolant to enter the combustion chamber and create a white cloud of smoke as it’s burned off, possibly creating a misfire, until the engine warms and the block and head expand to regain an adequate seal.
Let the issue persist for too long, however, and the result could be catastrophic. YouTuber and Focus RS owner MarkCup70 says he came across a dealer report for one car that had developed a warped cylinder head as a result of all the coolant loss, Autocar reports.