Interesting details from NHTSA site [Nov. 2013 1.6L recall]
573.6 (c) (6) - Chronology of Events
In July 2012, Ford issued recall 12S35 (NHTSA #12V-336) to address engine compartment fuel
lines that may have been potentially damaged during its manufacture.
In December 2012, Ford issued recall 12S41 (NHTSA #12V-551) to address engine
compartment fires in 2013 model year Ford Escape vehicles equipped with 1.6L engines.
Ford analyzed each subsequent warranty claim, field report, or claim alleging an engine
compartment fire, of any magnitude, for these vehicles. Ford conducted in depth review of
engines and vehicles reacquired from customers to analyze the potential causes of the fires.
Beginning in late August through October, Ford began to receive a series of engine
compartment fire reports, indicating a potential trend. An investigation of each incident was
immediately initiated. A teardown of engines returned from the field indicated engine
overheating and cracked cylinder heads that allowed oil to leak, and the investigation began to
focus on the potential for an overheat condition to cause the cylinder head to crack prior to
being damaged in the fire.
As part of the investigation, vehicles and engines were tested under severe load and
temperature conditions that were considered most likely to create a potential for overheating;
however, this severe testing was unable to duplicate a cylinder head crack. Review of the
conditions at the time of the fires also did not suggest severe loading or high ambient
temperatures were involved.
Subsequently, CAE modeling was used to evaluate what unique environmental and engine
operating conditions might lead to cylinder head cracking in this location. The modeling
predicted that under certain operating conditions, localized overheating of the cylinder head
could cause sufficient stresses to crack the head in the location found on field returns.
Additional testing was conducted through October in an attempt to replicate the field events and
correlate the CAE model, but was not successful.
In late October/early November, additional engines were returned and analyzed, and additional
cases of cylinder head cracking were identified. In November, an overheat crack was
reproduced on an engine dynamometer test.
During this engineering investigation, Ford identified warranty reports of fuel odor or leaks
related to engine compartment fuel lines on 2013 model year Ford Escape vehicles that were
previously remedied under Ford recall 12S35 (NHTSA #12V-336). Subsequent investigation by
Ford identified that some engine compartment fuel lines may have been installed incorrectly by
service technicians, creating a chafe condition. Ford's analysis indicated that, over a period of
time, the chafe condition has resulted in reports of fuel odor and leaks, but there have been no
reports of fires, accidents or injuries attributed to this condition.
On November 18, 2013, Ford's Field Review Committee reviewed the data and determined that
a safety defect exists, and that a voluntary safety recall should be conducted.