Ever See This Sort of Thing Before: High Lift Cam has pattern in it

[Zappacoop]

Hello,

I was doing the standard procedure valve clearance procedure on my 2021 GSA with 14,000 miles on it. The oil had less than 6k on it. And has been changed nearly by the book.

Please see photos: the high lift intake cam had a strange pattern on it, on one side of the bike. All the exhaust cam lobes looked nice and shiny. The other intake cam doesn’t have the same condition or at least no where to the extent.

Some important observations:
No metal shaving in oil
Next to 0 metal on drain plug
No actual deformation on the patterned lobe
It appears the pattern is only on the high lift lobe (it’s a shift cam engine; cam moves to from a low lift intake line to a high lift for variable valve timing)
Again, didn’t see it to the same degree on the other cams: the last photo will be the other side of the boxer engine for comparison.

The working hypothesis (all credit to a boxer engine guru) is that the pattern is from the wear additives being left behind under the high pressure and high shear working.

I am curious if anyone on here has seen this is other engines or if someone has more to add. I was quite worried at first admittedly, but after feeling the surface and not catching any peaks& valleys AND after talking to expert wrencher, I have since relaxed haha.

 

[Boomer]

Bad cam??

 

[gman2304]

Stock/OEM or aftermarket cams?

 

[JohnnyG]

Looks like some sort of plating effect. Did you try to scratch it off, or otherwise remove it?
Is there high moly or Zinc content in the oil?

 

[Zappacoop]

Bad cam??

I hope not haha. I am nervous that it is bad. No deformation that I can see

 

[Cujet]

I just watched a YouTube video about that system to see if it used roller followers. It seems to use flat tappet followers. Since the high lift cam is probably only used for short periods of time, I think it is unusual to see wear and/or deposits on it. I would be tempted to use an oil with high ZDDP and more than adequate viscosity. Consider M1, 10W-40 racing 4t motorcycle oil. It is among the best oils mankind has ever produced.

Have you tried to see if these marks wipe off or are easily removed?

Guess (and that's all it is):

The high lift lobe has far more follower load on it due to compressing the valve spring a much greater amount, and the load exceeds the oil's ability to protect. That looks like cam lobe scuffing to me, and not anti-wear deposits.

EDIT: Just a note to add that relying on additives to protect highly loaded parts, when oil viscosity can't do the job, is in some cases, asking for trouble. I'd rather see adequate viscosity, preventing contact, and ZDDP or other additives as a fail-safe. In other words, both are necessary.

 

[Zappacoop]

Stock/OEM or aftermarket cams?

Stock Cam

 

[Zappacoop]

Looks like some sort of plating effect. Did you try to scratch it off, or otherwise remove it?
Is there high moly or Zinc content in the oil?

I am going to try and see if it comes off. The oil that this had in it was whatever the BMW dealer used . I’m going to put Liqui-Moly Racing Synth 4T 5W-40 engine oil in it this time around.

 

[Zappacoop]

I just watched a YouTube video about that system to see if it used roller followers. It seems to use flat tappet followers. Since the high lift cam is probably only used for short periods of time, I think it is unusual to see wear and/or deposits on it. I would be tempted to use an oil with high ZDDP and more than adequate viscosity.

Have you tried to see if these marks wipe off or are easily removed?

Guess (and that's all it is):

The high lift lobe has far more follower load on it due to compressing the valve spring a much greater amount, and the load exceeds the oil's ability to protect. That looks like cam lobe scuffing to me, and not anti-wear deposits.

Appreciate you checking out a video on it. It’s a slick system for sure. I definitely drive spiritedly so it does see more use than others may.
Correct it’s a solid cam follower.

Any way to determine (besides wiping it off) to see if it’s scuffing with basic garage tools?

 

[bullwinkle]

Sure don’t want to scratch the surface, I wouldn’t use anything stronger than a fingernail or plastic razor blade. Doesn’t look good…

 

[JimPghPA]

I am going to try and see if it comes off. The oil that this had in it was whatever the BMW dealer used . I’m going to put Liqui-Moly Racing Synth 4T 5W-40 engine oil in it this time around.

Try using acetone on a rag to remove it. That certainly will not harm the metal if it's only a deposit.

The only thing stronger that I can think of that definitely will not harm the metal is there is a special lacquer paint remover that's used in machine shops for removing bluing that is applied to metal to enable etching through the bluing with a scribe to provide really fine lines for marking a piece of metal before machining. You would have to source that bluing remover through somebody who sells machines shop supplies or possibly McMaster-Carr. But that's very very wicked stuff and it'll eat through thick gloves in short time, and you should only use it in well ventilated areas and preferably fill the inside of your gloves with water. It's really wicked stuff. I hate using it every time I have to.

The acetone on a rag would be much more friendly to the user, it will still eat through gloves so filling the gloves with water is not a bad idea. You might have to put a little bit of elbow grease some time to it but if it's going to come off chemically acetone would probably do it without damaging the metal. And again use it in a well ventilated area. The fumes it throws off are toxic.

 

[Overfill]

I can't tell if the witness marks are things coming out-of-page (hills) or into-page (valley/pit).
Very important details.

Could be metallurgical problem if they are valleys (fretting or plating adhesive wear). If it is fretting, then it comes down to steel choice/ carburizing/ heat treatment QC. Or GD&T.

I'll let the tribologists answer to why they exist if they are coming out-of-page.

 

[Cujet]

Since cam lobes are hardened to Rockwell 60 or so, and to a depth of about 0.025 to 0.030 inches (almost a spark plug gap) wiping, scrubbing and other relatively gentle clean up methods won’t typically harm the lobe. Scotchbrite can scratch so best to avoid that. If it were removed, a polish would be acceptable

 

[Zappacoop]

Thanks for all the input so far. Truly appreciate it in trying to figure out my next steps.

So I just spent a good hour scrubbing both lobes with acetone with various methods. Cotton cleaning cloths, tooth brush, my fingernail. A lot cleaner but I don’t any of the marks lessened. With less brain cells than before, I just sent an email out to my local BMW dealer to see what they say.

I took some good images of the west using digital magnification. Suppose I don’t know enough to say, but the pattern is quite remarkable to me.

 

[twX]

A lot of BMW motorcycle engines have had excessive cam and follower wear due to defective coating on the rocker arms. There was a TSB for this in 2019, then another in 2021 that included a new rocker design.

The issue was from poor adhesion of the diamond like coating on the rocker arms. Maybe this hard coating is getting embedded in the cam.

 

[Chris142]

Looks like it's wearing past the hardness to me.

 

[Cujet]

The issue was from poor adhesion of the diamond like coating on the rocker arms. Maybe this hard coating is getting embedded in the cam.

The topic of wear in modern engines is one of those subjects..... I'm not yet convinced we have worked out the proper methods (for example coatings are one way we can get timing chain pins to live with 0W-XX oils), to allow relatively wear-free operation on many modern oils.

These coatings and/or surface treatments can be exceedingly expensive, are often a just a micron or two thick, and some hold up perfectly, right up until they don't.

We've been building reliable, high performance engines for over 100 years. The conventional tried-and-true methods are very well understood.

Unfortunately, without knowing what (if any) coating they used on the follower, I can only guess at the situation. It would be interesting to see what the wear surface looks like on the follower. Some of these coatings shed oil, and that in itself could present a problem.

Timing chain pin coatings, so 0W-16 can be safely used:

https://www.partinfo.co.uk/files/febiTippTritanCAR_GB.pdf

Thinking aloud here, I'd send off pictures to BMW, on the off chance that they acknowledge the issue.

 

[Yourhomiematt]

My opinion is that you are in the beginning stages of cam failure

 

[sloinker]

Looks like a dry start. Maybe the German applying assembly lube took the day off.

 

[SubieRubyRoo]

I am going to try and see if it comes off. The oil that this had in it was whatever the BMW dealer used . I’m going to put Liqui-Moly Racing Synth 4T 5W-40 engine oil in it this time around.

It’s not going to come off. You’re breaking through the induction-hardened layer which is only about .020” deep. After that, it will start to shed significant material in short order. I agree with Cujet’s assessment that you need more viscosity and more ZDDP/moly, ASAP.