A sad day in 60K land

[shojuan]

Well, I guess 148,000 miles and several neglected (11,000 miles between changes for three of them ) oil changes is not without consequence for me. I just pulled the front valve cover and while everything looks reasonably clean, one of my cam lobes has some pitting on the tip. It's a number 6 intake, the second from the top right in the picture:

shoot

It was within spec, .008". All the other lobes in front look good. I haven't pulled the rear cover yet, so hopefully there won't be any worn lobes back there.

BTW, the car has never run synthetic oil. For the last 45,000 miles it's had 5W/30 Mobil 0 drive clean oil because it's pretty cheap at walmart shoot

I'm tired now. I think I'll take a long nap before digging in some more. I guess I'll be on the lookup for some intake cams in the next 60,000 miles.

Rick

 

[DavidT]

At least yours looks cleaner than mine!

Can you post a close up pic. of the pitting

 

[shojuan]

Some varnish on the valve train and no wear beats a clean valve train with cam lobe pitting in my book. Yeah at least it is pretty clean considering the mileage. There are some bits of soot in the corners and a bit of varnish here and there. I took some photos of the pitted lobe but photoisland doesn't want to give me a link right now. The detail on the photos is pretty crappy because my digital camera is a really low quality bugger without much closeup abilty. Suffice it to say if you've got pitting, you'll know it. It looks like little dark spots (in real life, not the photos) and the finger nail can really feel them. When I shined a 300 watt shop light on the lobe to snap the pics with a small aperature for good focus, I could really see the detail of the pitting. It made me sad.

I'll post the pics when photoisland starts cooperating.

So guys, is this the end of the world for my little cam lobe? Am I going to be able to drive the crap out of my car for the next 60,000 miles thumbs_u when hopefully I'll have a fresh cam to swap in or is that little lobe going to tear up its shim long before then? eek!

Rick

 

[shojuan]

Here are two pics. Sorry they don't show more detail, my digital camera sucks.

I think you have to use your imagination a bit to see that there is wear on the second from the top right lobe. Unfortunately, it is there.

Rick

 

[RStalveyARFF]

that engine is extremely clean. Keep on using that oil!

 

[DavidT]

Could it be too clean?? Could that be why there is pitting? I dunno... it looks like it never had oil in it, it is sooooooooooooo clean. Has others looked that clean with that many miles??

 

[RStalveyARFF]

It had gone 11k between oil changes 3 times? Sounds like the oil started breaking down. For 15 bucks, it's cheap insurance to change your oil every 2500-3000 miles, and keep your valvetrain smooth.

 

[185K89SHO]

Mine is pretty clean with 190,000 on it. I have some pitting/wear on 1 exhaust cam lobe in the front head. I just made a mental note of it, set the gap, and put it back together. If I come across a set of cams for cheap, I'll but them.
John
89 SHO

 

[nc89sho]

mine was pretty clean also when i did mine (135K)

 

[shojuan]

dkautumna:
Could it be too clean?? Could that be why there is pitting? I dunno... it looks like it never had oil in it, it is sooooooooooooo clean. Has others looked that clean with that many miles??

I think it's that clean because it's had predominately highway miles. My wife has been using the car for a daily driver for the last two years 45 miles to work and 45 miles back. That kind of duty cycle tends to be easy on an oil.

BUT, yeah there's no excuse for the 11,000 oil change intervals. I guess the wife's scowls and comments about limited funds kept me out of the auto-supply section of walmart and I didn't really have a good concept of how quickly she was accumulating miles. That's really lame (holds head low in shame). I used to change the oil in my 914 every 1500 miles when I was a kid. What have I become?! (looks up to sky with fists clenched)

Rick (sinner among good oil changing men)

 

[sdpatt]

Sorry to hear about the cam lobe wear. What did the shim look like under that cam? If there aren't any indications of excessive wear, the pitting may not be a fatal flaw. If the shim reveals scratches or a noticeably dished surface, the cam will be just as ******* a new shim.

I suspect the pitting is more a result of corrosion from the exhaustion of the anti-corrosion additives in the oil during those long change intervals. Lack of lubrication shows up as oval shaped rings, much like the rings on a tree trunk, that indicate the depth of the wear on the hardened cam lobe tip. The lack of lubrication would have affected most or all of the cam lobes. There may also have been a local metallurgical aberration that helped to create the pitting.

Let this be a lesson to all that changing the oil frequently with a quality oil is the best and cheapest preventative maintenance that you can perform to ensure the long and healthy life of a internal combustion engine. Yes, it's a run on sentence, but don't you want your car to run on too?

Here is a photo of the 60,000 mile engine that was lubricated by Mobil 1 or other synthetics all its life. The engine was very clean inside, but showed minor wear at the leading edge of several cam lobe tips. That is quite premature for a SHO to exhibit lobe wear. It was difficult to get a photo that really showed the wear, but you can tell the difference in the texture of the surface inside the highlighted area. A similar wear pattern was exhibited on the cam lobe on the right.

<small>[ September 02, 2002, 09:33 PM: Message edited by: sdpatt ]</small>

 

[shojuan]

Sorry not to get back to you sooner, I wanted to take a good look at the shims before replying. I *am* really grateful that you replied to my original post so quickly Scott, and everybody else.

It turns out there were 4 cam lobes with pitting. All but one of them had the pitting just off of the tip. The one lobe had the pitting right on the tip.

The shims under the pitted lobes didn't look so bad. There were a few shims under the unworn lobes that looked worse. I think that your corrosion theory might be right. None of the offending lobes had an abnormal appearance on the wearing surface. There was more of a jagged edged dark looking pattern on the peripheral outside portions of those shims. The centers of the shims looked just the same as on all the other shims, smooth with a faint visible round tree ring pattern.

Since my shims weren't all torn up or anything, hopefully my cams will last a good long while after all (hopefully!). I wonder if I should still keep my eyes open for a good used set however?

Three intakes were out of spec (.356, .356, .279).
I used new shims to get each valve to the minimum of the allowable range. I think the 35% coolant and water wetter will keep my head temperatures under control. Don't want any burnt valves! wink

Rick

 

[shojuan]

Here are some pics. The spark plugs are there to show the big ass gaps on 13 years old, 148,000 mile plugs.

The four shims on the right are the shims that were under the pitted cam lobes. The two shims to the left of those were under normal cam lobes and have a similar discoloration pattern. The shim on the far left is the typical shim in good condition that I took out. On the one good picture of the middle two shims, the far left shim has a funky splotch. That's just a shadow.

 

[luigisho]

Check ebay. M. Betchel is selling some (maybe just intake) cams right now.

 

[shojuan]

Thanks! I'll talk it over with the wife. I'll need exhaust cams too because two of the pitted lobes were exhaust. But I understand I can use either 3.0 or 3.2 exhaust cams because they are the same. So those should be easier to find down the road and less expensive.

Rick