The Ford Focus RS is a serious hot hatch with a high-output version of the 2.3L EcoBoost and an all-wheel drive system featuring a 'drift mode'. But there is a serious issue that could make the RS not so hot.
During the past year, numerous RS owners have been reporting of a plume of white smoke coming out of the tailpipe, a tell-tale sign of burning coolant and possibly a head-gasket failure. A Ford spokesman confirmed to Autocar this issue and said that it is affecting models from 2016 to 2017, and with mileage as low as 6,000 miles.
The Ford spokesman said the company is “working on a repair for all customers,” hinting that a fix could be rolled out to models that are not currently affected.
“In the meantime, if vehicles show these symptoms, customers should visit their dealer for an inspection and repair under warranty,” the spokesman said.
No reason was given by Ford as to what the problem is, but the company has replaced several engines under warranty that are "built to the latest specification".
The issue seems like a head-gasket failure, but that might not be the case. Members on the FocusRS.org forum speculate the issue comes from engine block distorting over multiple heat cycles. This creates an opening between the block and cylinder head that the gasket cannot seal, allowing coolant to enter and cause the aforementioned problems.
Interestingly, the Mustang which uses the same 2.3L EcoBoost isn't affected by this problem. It uses a different alloy for its cylinder head and engine block than the Focus RS.