Skypilot797

Have a 2003 ZO6, custom comp cam 228/232 xe-r lobe, 114 lsa. We installed this about 60,000 miles ago. Double springs, all the modes, etc. Dynoed @ 440 rwhp & 405 rwtq.
Several weeks ago, when starting cold, the idle was low by 200 rpm and then would slowly come up normal of 825 rpm. Shortly their after, like maybe 50 miles at most, 5 days, this weird sound like tapping/slamming started going on in center of motor. We pulled valve covers and did compression checks, all looked fine. Then drove it over to a friends to take the heads off. Barely got over their as it really started to get loud on the tapping/slamming noise.
All the hydraulic rollers were stock ls6 rollers. 14 were either now flat spotted or the rollers were very bad, as in pitting. Cam lobes are pitted. Pulling out the cam tomorrow.
Heads, valves, springs & cylinders all look fine, even compression was 180/190 cold engine.
Am just amazed how fast the rollers and cam all started to come apart. Luckly we are doing the work, so am spared at least major expenses.

MawneeC5

Sounds like you had a lubrication failure somehow. I'd definetly try to track down the cause before putting new parts in to find it the hard way

Oil pump failure?
Oil not filled properly after a change?
Wayyy too long since last change?
Oil too thick for colder waether?

I'd be concerned about your rod bearings too.

KCvetteowner

Had the same on an aftermarket cam after about 18k miles if I remember correctly. Cam has some well worn groves. I would recommend adding a melling oil pump and morel lifters. You can also go link-bar lifters and get rid of the plastic lifter trays as an option.

Skypilot797

We looked at all those issues. Been running Mobile 1 since the motor was new. Never has been a pressure problem as it has a high output oil pump. Sits around 35-40 psi when warm and idling. I am the only one who dives it, never a loss of oil pressure. No high temps either. never been run low on oil. We did change the oil as the first tapping/slapping sound was heard. Oil changes, etc. have all been kept done at regular intervals. Not been a track or drag car either.

Since the rollers all appear to have the same pitting, as the lobes on the cam, is whats different. I could understand maybe loosing one or 2 lifters, but not all of them. When we get the cam out, we will be able to see the cam bearings and how they look. The rollers still spin freely.

The xe-r lobe is really agressive on its ramp rates and with the 60,000 miles on it, maybe it was just plain wearing out. But all the lifters and lobes had this pitting on them where they both were simply wearing/worn out.

Ya, thanks for the heads up about the bottom end, we are planinng on looking their if the cam bearings show damage. But all the upper valve train looks fine and as good as new. Cylinders all had good compression, heads and valves all look good, no excessive oiling/burning going on. Push rods are straight, no burnt oil anywhere.

Just weird how it just broke down so fast on all the lobes and lifters. Its like the lobes lost their hardness all at the same time which then started the pitting on the lifters. None of the lifters were turned in their trays and had no tray damage. Yet some of the lifters had flat spots. Some had 2 flat spots on them.

Ya, somethings not right. Maybe it caught a virus............

mcm95403

Sounds like excessive spring pressure. Unusual to see it on a roller cam, but I'd be interested to hear what Comp Cams says if you ship it to them for inspection.

Skypilot797

Good idea and will see if Comp will look at it. Have double springs and its what recommended for spring pressure. Remember its on a XE-R lobe which is a very aggressive lobe. My springs are for lift to .650 and never had a floating valve problem.
My Lift is just under .6 on both intake(.595) and exhaust(.598)

The duration and LSA are more mid size on mine rather then some that are on a 112 or 111 lsa and high 230's, low 240's. My heads are ported with bigger valves and have been milled to 62 cc and not to 59 cc which some even go to. The geomerty was checked and doubled checked and all the upper valve train apears to be fine.

Sure glad when it caught this virus it didn't sneeze.....

AU N EGL

yup might have been too much spring for that cam.

Your cam with a .595 and .598 lift so that should have been a beehive springs. PLUS. 60,000 miles is way to long without a spring change.

panteravetteman

I know you guys are talking aftermarket but i thought I would throw this in: At 51k miles I suddenly heard a "squeaking" noise that rose and fell with rpm. I took the car to the dealer who to his credit tore the engine down and replaced the cam and lifters at no charge. Three lobes on the cam and corresponding lifters were severly pitted and worn. Go figure as my car has not even been parked near a track, let alone run on one. Plus I have replaced my Mobil1 every 5k miles without fail. Aside from the occasional onramp or freeway burst to quiet those pesky ricers, I have pretty much babied my car. it is a bit dicouraging to encounter this wear at such relatively easy and low miles.

zeevette

Since the OP said the cam is 60k miles old; then I imagine it was some time ago? Comp had a whole lot of lobe failure, due to a fault in the hardening process. This happened to lots of guys a few years ago.

Russ K

If your using the 5W-30 or 10W-30 Mobile or any oil that is designed for new cars you will have cam & lifter failure. You need to use a performance oil such as a 15W-50 Mobile or Joe Gibbs.

Or at least add a can of GM EOS at each oil change.

Russ Kemp

ssrallyred

This , GM had a major wear issue on camshafts in the 80's also from the lack of harding on their cams.

ctusser

Since you are using an aftermarket cam with aggressive lobe design, have you ever checked the spring tension? 60K miles is a lot for those lobes. If the springs are getting weak it is possible there is some valve float in the high rpms.

81c3

My stock cam was pitted and had some deep grooves in a few of the lobes at 75k miles. Engine was completely stock from pan to valve covers. I did some investigating, found nothing... I replaced the cam with a Torquer V2 and beehive single springs good to .625 lift. Did the oil pump and push rods at the same time. Its got about 10k miles on it now and seems ok so far. Ive been using Castrol Edge since the cam swap.