blown94

Ok guys heres an odd one. I havent torn the bottom end down on this engine yet. I started to do a cam swap and pulled the top apart and when I got the cam out I found the last 2 lobes on it were pitted across the top of the lobes and spec'd out .007 in. less than the others. Leak down tests came up great for cylinders and the lifter valley and under valve covers look immaculate. No sludge or carbon buildup or anything. Any idea what caused this?

Dave88LX

Mine did the same thing, I don't know if that caused a spun rod bearing, or if the spun rod bearing caused that...but my 2 corresponding lifters were ate up too. I'm not sure but it seems as though it MAY be caused by the lifter roller sticking?

Spinner

Generally its caused by a sticky/failing/failed lifter. Replace the whole set.

blown94

ttt

1racerdude

Generally if the cam has pits (small pin holes) the heat treat is gone on the cam exposing softer metal. The case hardening is only good to .005-.010 deep so .007 is in that area.I'm affraid if you run it it will peel a lobe off filling your new engine with metal.If it were me I would upgrade or replace it.

blown94

Ok, to ressurect an old post by myself,.....i finally tore down the top of my ORIGINAL engine that was pulled and replaced by earlier spoke of engine. I did replace that cam and ive put about 10k miles on the car since. So anyways, the original engine was making a scraping sort of noise and I couldnt easily diagnose it so I just replaced it. I finally tore the top end apart tonight and what do you think I found? The same exact scenario that I found in the other engine. The very last cam lobe and corresponding lifter roller were pitted. This makes 2 engines with the same scenario, odd huh? Im guessing now that this is a more common issue than I thought. Is it the heat treatment in the lifter, or the cam itself? And why is it happening to the rear cam lobes??? Last ones to receive oil?

gex598

My LE2 cam just did the same thing #8 & #6 exhaust lobes. The number 8 the lifter roller was flat but the number 6 is was fine, both lobes were pitted. I was gonna sent it for hardness testing but I decided to keep it as a 'hey look at this' toy, it goes well with the destroyed lifter...lol. I do like my new Lunati cam its shinny!!!

1racerdude

Comp cams strikes again.

blown94

Both my instances were bone stock GM engines. Virgins.