Continental IO-520 lifter cam spalling

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Continental IO-520 lifter cam spalling

I represent 2 U206G’s (1982 and 1983), an A185F (1976) and a 1976 C310R each with factory spec, normally aspirated IO 520 engines. Since 2012 there have be repeated cases of spalling lifters, 4 of which have damaged the cam. 4 of these cases have been factory rebuilt engines. 2 of these shredded enough metal to impregnate particles into the oil pump housing and cause diminishing oil pressure. In the process we have begun the use of Camguard products along with oil analysis. No improvement seems to have occurred. This is no criticism against Camguard since they have gone out of their way to help.
The cost of course is overwhelming. Consultations with Continental, Ram, Aircraft Specialties have proven inconclusive. To avoid further damage we implemented visual lifter and cam inspections every 200 hours of operation which is more invasive than desired. In each case this removal inspection has yielded lifters which have shown spalling and required exchanging.
Related data:
Oil changes at 50 hours or less
Type oil: From 2012 until 2016 Phillip XC20W50, presently Exxon Elite to try something different
Hours of operation: 200 to 300 hours annually
Engine preheaters are used during sub-freezing temperatures
Cruise setting: 65%
Type of operation: Flight school training

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interesting

We have personally found lifter cam spalling on two engines, one TSIO-520-M and an O-470-R. Ive also heard from another 414 operator who found spalling on both engines during an inspection. 

We have found the use of multi-viscosity oils to cause more of this kind of issue since their introduction.

Think of it this way, the 20w50 oil behaves like a 20 weight oil and drains off the engine parts more quickly if the engine has been sitting. Think of how many of your customers have 'low time' engines that are 25 years old, corrosion plays a big part in the failure of components in these engines rather than mechanical wear. Thicker oils coat the surfaces for longer during storage so that the pitting corrosion of the cam and lifter surfaces or spalling and wear due to the pitting isn't as big a factor.

We only recommend W100 (50 weight oil) or W80 (40 weight) for winter operation in our engines and haven't had as many of these issues. 

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