What would cause this??

[Rawze]

(11-27-2021 )JMBT Wrote:  Hello all, I have a 2012 Volvo with a CM2250, and 855k miles. I just popped the top to do an overhead. It has been about 95k since the last overhead I did. Everything up there is nice and clean. All of the cam lobes look beautiful, but on the first three sets of rocker followers, cylinders 1,2,&3 there are lines staring to form. The back three still look great. I cannot feel any of the lines with my fingernail so I don’t think they are very deep yet, but I was wondering what would have caused this? And how worried should I be??

Thanks in advance! JMBT

Letting road dirt get onto the rollers while performing an overhead valve adjustment or re-installing the engine cover and its got dust/dirt on it is a very common cause of that streaking. that or the valves are riding the cam because the overhead is not adjusted often enough vs. the amount of head wear. Should be done every 250k miles or so .. or roughly 4,000 engine hours. Maybe more often if you idle a whole lot or have a lot of low rpm PTO.

Mine never got those streaks in them like that. Valve cam made it 1.3 million miles .. number 6 started to get a bit flaky finally, but rest of it was still looking really good. Injector cam still looked mostly new, but i went ahead and replaced them both at 1.3-mil.

- I always also ensured everything is extremely clean + cleaned the cover really well + washed any dust off all my rollers/cams, etc. with a bit of WD-40 spray each time I adjusted the valves, just before putting the cover back on. I also cleaned the ledges around where the cover sits too, usually scrape all the dirt and dust off while using a tiny shop-vac.

- I also make everyone who comes here do this when they are over here and do overhead adjustments too.