Quote:
Originally Posted by CrowsFeast
I haven't particularly looked into the valve spring issue but I seem to recall hearing something about it being a heat treat issue that caused them to be susceptible to failure (which would make sense to me)
Since one supplier would be selling springs to several different manufacturers I wouldn't be surprised to find that this became a widespread issue. The heat treat problem (if that is in fact the issue) might not be that the treatment was spec'd wrong; it could be that one of the suppliers furnaces was running out of spec or miss-reading the temps.
Just my shot in the dark with my understanding of how such things work, but with no research done on this specific case.
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No it was not a manufacturing issue. That was speculation.
It was a design issue that they caught and corrected. The springs themselves were not the problem. The use of that certain spring in the application was.
"The basis for how the recall population was determined: Vehicles equipped with
engines which have an improper design of the valve train which may result in
excessive stress to the valve springs are included in population. In May 2013, the
lower limit tolerance of the valve spring wire diameter was raised to compensate for
the excessive stress.
-How the recalled products differ from products that were not included in the recall:
Products that were not included in the recall are as follows:
1. Products that do not have valve train containing valve springs manufactured with
the original width of the tolerance of the spring wire diameter.
2. Products that were manufactured before January 2012, when introduction of new
type engine and production volume increase resulted in the rate of valve spring
fracture to increase." https://static.nhtsa.gov/odi/rcl/201...8V772-5413.pdf
Bad parts due to design/materials/processes/assembly methods happen all the time. The majority get caught by the parts manufacturer or the QC at the assembly plant but sometimes things slip through. This can be especially prevalent in new engines. In the Subaru case the design specs of the spring looked good on paper and passed all the engineering reviews but in fact they simply were not the right strength. There is nothing beyond the fact that the GM issue is also springs to tie them together.
Everybody needs to stop thinking that internet speculation is fact and dig a bit further. The Subaru case is well documented for anybody that takes the time to read it all.
https://www-odi.nhtsa.dot.gov/acms/c...72&docType=RCL