Cam Lobe Wear. What should it look like?

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Geonerd

Geonerd

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Here are some more "Bored with a Camera" pics from my 92 Accord.

Visually, the lobes are smooth and bright, with no sign of scuffing, pitting, discoloration, etc.

However, my P/S camera's macro is recording detail my middle aged eyes are missing. I suspect the on-camera flash is accentuating the striations, but it's still a little unnerving to see the numerous small streaks - evidence of metal parts experiencing unhappy moments.

The car is a SOHC, with the valves being driven by rockers that slide directly on the cam. There are no rollers. I suspect/hope this scuffed appearance is normal.
whistle.gif


Later this fall (when it cools off!) I'm planning to pull the rocker arm assemblies and change the lower plug-tube o-rings. When I do, I'll make a point of inspecting the arm's contact area for signs of similar smearing.

Comments welcome!
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Lobe_Wear3.jpg


and

Lobe_Wear2.jpg
 
That's just a reflection.

These pictures should have been taken without or at least with a heavily diffused flash.
 
Use a micrometer to judge wear, this visual inspection isn't sufficient. Also, there are no wear ridges or grooves. This looks like a perfectly healthy cam after than many miles.
 
Originally Posted By: friendly_jacek
Fess up, you did not use Mobil 1 HM all the time ,did you?


Bought the car used at 130K. records indicate that the prior owner maintained it fairly well, but I obviously don't know all the details.

I've been running M1 10W-30, usually mixed with 1 qt. of 15W-50 for several years. Switched to straight 10W-30HM at the last OC.

Pictures are of different lobes. I was trying to shoot near the top of each lobe, but wasn't being terribly retentive about it.

As surmised, there are no ridges, flat spots, blatant scuffs or stained areas on any of the cam surfaces I saw. The P/S camera's flash lighting is very harsh - some of the reflections look like wear zones or even steps in the cam. I've got an MP-E 5X macro for my DSLR and am now itching to take some high mag photos of the lobes. Stay tuned! (The surface will no doubt look like a war zone at high magnification!)

I'll try to measure lobe height next time I'm under the hood and/or might even pull the cam when I change the timing belt this fall.

Thanks folks!
 
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Looking at the bit of incidental reflection above the "horror" area, and on the adjacent lobes, I'd say that you have no problems.

The horrific looking bit is probably due to (lots of) scratches, providing an ideal reflector back to the camera, and magnified by the pixellation of the camera.
 
Can you feel the scratches with a finger nail? As others said, probably normal wear and tear at 190K miles.
 
Given that this engine does not have roller followers, and considering the mileage, and somewhat unknown maintenance history leading up to the 130K mark, I think it looks pretty darn good.
 
How about the rocker ? Is it dished or grooved? What about the valve clearance? No change is a good sign.

Those pictures look bad at first glance, but a personal viewing may show a different story.
It may simply be slightly rough machining that wore off the high spots, and stayed the same for many thousands of miles now.
 
Originally Posted By: mechtech2
How about the rocker ? Is it dished or grooved? What about the valve clearance? No change is a good sign.

Those pictures look bad at first glance, but a personal viewing may show a different story.
It may simply be slightly rough machining that wore off the high spots, and stayed the same for many thousands of miles now.


Getting a look at the rocker follower pads requires pulling all the upper valve gear as a unit. Each bank of rockers pivots on a common shaft. I want to install new plug-tube o-rings some day and will need to pull the hardware to do so. Will check for follower wear at that time.

Valve lash was excellent. Of 16 valves, only 3 were out of spec, and those were off by only 0.001" Two were 0.001 tight, on was loose. I don't expect to see much follower wear.
 
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Pictures are of different lobes. I was trying to shoot near the top of each lobe, but wasn't being terribly retentive about it.

It's hard to tell but the first photo looks like the base of the lobe, if it is then it shouldn't show any wear.

I think we are seeing an optical illusion enhancing the look of scoring.
 
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