871 cam wear or corrosion?

[DosGatos]

doesn't look like wear. looks to me like corrosion from the engine sitting. ran for about 10 min a month ago (didn't get hot) and then two months prior to that for about 30 min. otherwise the trucks been sitting since the beginning of october 17. (5 mo) the residue rubs off with the oil but leaves behind these stains (my opinion). there are artifacts on the follower that look worse in the image than to the eye (lines running in direction of rotation) but no crazing or major metal failure. engine has 755k. jake clearances are less than 7mm. valves are all tight.

don't want to touch the cams to remove the stains. think it would do more damage than good.

[Rawze]

Big engines don't like to sit for months/years without cranking. I call it "Parkinglot Rott".

I saw pictures of one recently that sat for a couple years without the engine being cranked or even barred over once in a while. Moisture got onto the top of a couple pistons, pitted out the liners from the inside, then caused severe blo-by issues after it was finally cranked up.