Early cam wear pattern pics

So I've been checking my cam lobes the past two oil changes. First time around, my chamfers were intact and there was some very light concentric ellipses on the lobe tips of 2 and 3 exhaust.

This time (16k km later) I found evidence of some progression. Lobes on cylinder 3 didn't really change. #2 exhaust lobe tip has a bit more flattening but it is offset towards the centre-line of the cylinder.

A new pattern I saw was almost like a follower "slap" on the backside of the cam lobe. This was present on exhaust lobes of cylinders #2 and #3. There is also a bit of a burr on the lobe tip of #2 exhaust along with the flattening.

Here are the pics:

Cylinder #2 Exhaust Lobe (backside).



Notice the pattern is offset towards the middle of the cylinder. When I say backside, I mean the part of the cam lobe that follows the tip on cam rotation.

Cylinder #3 Exhaust Lobe (backside)



Same type of pattern.

Cylinder #2 Exhaust Lobe Tip



This poor picture attempts to show a flattened area on the lobe tip. Again, this wear pattern is offset towards the mid-line of the cylinder. The chamfer was still present but reduced in width and there was a burr on the side of the tip that I could feel with my fingernail.

Talk amongst yourselves.

Bummer... I think my original wear pattern was similar. I don't know why it is wearing like that. It seems almost counter intuitive in a way. But it does make sense... heat/exhaust stroke maybe?

btw it looks like you have the 2nd picture labled wrong... that should be cyl #3 exhaust no? To left of bearing cap #4 is cyl #3, and lobe on right of cyl #3 is exhaust.

SBAtdijetta said:

Bummer... I think my original wear pattern was similar. I don't know why it is wearing like that. It seems almost counter intuitive in a way. But it does make sense... heat/exhaust stroke maybe?

btw it looks like you have the 2nd picture labled wrong... that should be cyl #3 exhaust no? To left of bearing cap #4 is cyl #3, and lobe on right of cyl #3 is exhaust.

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Ahh! Thanks for catching that! It gets confusing when you take a bunch of pics and everything looks alike. Captions now corrected.

^^^ Agreed! I have looked at sooo many now that I think I can tell from the wear patterns alone... I kid lol. But you can tell from the rockers and bearing cap numbering pretty quick.

More importantly.... What do you think about those wear patterns?

Ya, I see that wear on the tip, that is alot of wear, all else looks acceptable..

Run it, do something with the oil though to prolong life, how many miles..

2foot breaker, thanks for the effort & info. Interesting pattern. I guess I will pull my cover (on edit) again also @ the next OCI.

SBAtdijetta said:

More importantly.... What do you think about those wear patterns?

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I think the wear pattern in the first two pics just shows the importance of surface area on wear. As the lobe rotates with zero lift, pressure is high due to the small surface area. Once the ramp of the lobe starts, the surface area is suddenly increased and then suddenly decreased when the lobe tip contacts the follower.

All this typical for any flat tappet cam. What is not normal, is lobe wear from this. I checked my IDI cam and it did not have wear on the zero lift part of the cam lobe. Also, the offset pattern is seen again, which indicates uneven loading of the follower.

Personally, I think a large reason we see the wear start is the narrow lobe width along with the hot environment of the middle cylinder exhaust valve followers. This is obviously not a new theory. Another reason the wear starts, is my theory of the follower tilting slightly in its bore.

I have been using ZDDPlus since my last oil change, and obviously it didn't completely stop wear . I also used 5w-30 Castrol SLX OE. I am now switching to Rotella T 5w-40 CJ-4.

Another solution I was thinking of was using a slightly lower rate valve spring. I don't really like this idea since you run into all sorts of other issues like valve float, etc.

Mach1 said:

Ya, I see that wear on the tip, that is alot of wear, all else looks acceptable..

Run it, do something with the oil though to prolong life, how many miles..

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Yeah, I'm going to continue to run it for a while. I did add ZDDPlus at the last oil change. At that point all the lobe tips looked great, with no burrs on the edges. It's got 96000 km.

I have switched to Rotella since yesterday.

The wear pattern on the valve lobes is toward the cylinder center. The injection roller is pushing the cam down @ the center. Is it possible that the cam is deflecting under the injection roller loads thus giving the observed wear pattern here and the bearing wear pattern observed elsewhere? Hard to fathom that this could happen but sure would explain a lot.

2foot, check out my post in the lube section, your wear is not bad, I wouldn't change anything..The ZDDP works..

Bob, you are going to be surprized when you pull your VC. Hope its OK...

Bob S. said:

The wear pattern on the valve lobes is toward the cylinder center. The injection roller is pushing the cam down @ the center. Is it possible that the cam is deflecting under the injection roller loads thus giving the observed wear pattern here and the bearing wear pattern observed elsewhere? Hard to fathom that this could happen but sure would explain a lot.

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Could the loads on the rockers be that high? Well from the injectors that is. In order to load the rockers enough to deflect the cam itself?

Would that not imply that the cam is under enough load/force to be bending it ever so slightly? Or am I thinking about this all wrong, and way off your thought process?

Thanks! LOL I am all questions and no answers after what you said above ^^^ .

I could certainly see the injectors causing some microscopic cam bend, the problem is this off centre wear is found all the way around the lobe. If it was the resistance of the injector, we'd see it only or at least, more pronounced during the pressurization of the injector phase in the cam cycle.

2footbraker said:

I could certainly see the injectors causing some microscopic cam bend, the problem is this off centre wear is found all the way around the lobe. If it was the resistance of the injector, we'd see it only or at least, more pronounced during the pressurization of the injector phase in the cam cycle.

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Valid points. Hindsight on this will be wonderful.

The flaw is in the design, imo.

I just pulled the cover on my '06 today (with the new engine after the DMF disaster) and in 18,827 miles, my cam is showing some pretty scary signs already. This engine is way new, made in march of 08, and it has the nitrided cam followers. Just for the hell of it I rolled a lower bearing out on the belt end, and had to run away quick...... and I'm still glugging on a bottle of Johnny Walker trying to stop the shaking. The bearing is already into the copper.

The 06 will be sold as is where is. Too bad, it's like new otherwise. Great car, junk engine.

Too bad VW didn't use a dual camshaft design for the PD. One cam for the valves and one for the injectors. Would have taken a bit more space but would have been waaayyy more reliable.

Rod Bearing said:

The 06 will be sold as is where is. Too bad, it's like new otherwise. Great car, junk engine.

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Welcome to the club! Sold mine too.

2footbraker said:

I could certainly see the injectors causing some microscopic cam bend, the problem is this off centre wear is found all the way around the lobe. If it was the resistance of the injector, we'd see it only or at least, more pronounced during the pressurization of the injector phase in the cam cycle.

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I seem to notice there is normally more wear on the back side of the lobe. This would support the theory no? Then after the lifter starts getting chewed up it would certainly start dulling up the lobe tips as well...?

Could be? Maybe...