Pinched air filter - how much possible damage?

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So my '11 E350 that I purchased used @78k miles with reasonable Carfax service records (not MB dealer service) had an uncharacteristic growl from its engine under acceleration that I never heard from my '09 C300 with same but smaller displacement engine. As I had done the filters on my 3.0 C I figured what the [censored] lets go ahead and do the ones on my E since they will be due in 2k miles.

First one seemed seated just fine, was a made in China STP that comparing side to side with Genuine MB appeared to have maybe 80-85% of the amount of pleats. Based on the dirt load in the I would venture to guess that this filter set had 30-40k miles. My horror came when I opened the drivers side bank filter housing and found a huge pinch where the filter seal dove down into the housing and I found a leaf stuck in the gap. Washed up the engine cover and housing, let them dry, installed the new filters and popped the cover back on.

So I am wondering with this possible massive filter leak for 30-40k miles should I worry? The uncharacteristic growl is gone now I have the new filters in place so I think I have stopped the leak, should I worry about the car getting 50% unfiltered air for so many miles or just take care of her and motor on? The M272 is pretty stout but this bargain E350 I bought is already exhibiting some valve lash noise so trying to get ahead of any neglect it may have seen in its first 7 years.
 
Forgot to mention funny enough my prior '09 3.0 M272 had the "normal" main bearing knock on warm/hot starts with a quiet valvetrain, now my '11 3.5 M272 has no lower end noise but has valvetrain noise. As stout as the M272 is ('09 and later) I apparently just can't win with this engine line.
 
There likely was some. No way to tell though, unfortunately, at least without opening it up and doing measurements.

Highly likely that not all air went through that gap. But whatever small fraction is not reassuring.

I'd pull the filter, maybe some more of the intake, and see just how dirty it is in there. Maybe it's bad, maybe not. The cleaner it is along the length, the better off you are.

Assuming you don't drive on dirty or dusty roads much, the net result may not be that dire, but see my first statement...
 
No you shouldn't worry, since it'll do no good, but you can if you want to.

Possible partial remediation (as well as cleaning the intake tract, which has already been mentioned) might be an oil (and filter?) change, if you havn't done that, in case of silica getting past the rings into the oil.

Filter change might not be worthwhile since stuff the filters got is now mostly harmless, though I suppose there might be some marginal sizes working through gradually.

The sad story with this is that the silica becomes embedded in the piston and cylinder surfaces so continues to act as an abrasive long term. I dunno if this story is true, but its sad, so it probably is.

Look on the bright metal side. Maybe the backs of your intake valves look sandblast-shiny now.

If you suffer from morbid curiosity you could maybe get some indication of severity from silica numbers in a UOA, but it'll be an uncertain indication, and it won't fix it.

On the face of it, qa more direct indication might be silica numbers in oil back-flushed from the oil filter, but AFAIK there's no standardised technique for that, and no "normal" baseline, so it probably wouldn't be informative.
 
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A small amount of unfiltered air got through, but the majority was filtered. I wouldn't worry about it.
 
If you still have the oil in the crankcase from this interval that was exposed to the dirty air, maybe have a UOA done and see how many PPM of contaminants got through?

Check the cylinder walls with a boroscope?
Do a compression test with factory specs to check? I'm just being an [censored], I don't think it would have done that much damage.
Good advice was already given (look for dust past the air filter, if dust did pass it, it would coat the path behind without a doubt).
Check the throttle plate for anything stuck to it or jamming it (believe it or not, debris has done this before).
Check the MAF to see if it's contaminated and clean it?

But yeah if I ran into what you did I'd be shocked and [censored] off, that is not a good sight to see.
 
As has been said look at the tube after the filter, if its not all dusty its probably didn't ingest all that much. Do a UOA and look for high aluminum numbers on this engine.
 
Sorry, "silica numbers" was wrong. I think a standard UOA only does elements, so it'll only give you silicon.

That's usually taken to indicate silica contamination, but there are other possibilities like RTV and maybe anti-foaming agents and probably others I can't remember.

I dunno offhand if there's a commercially available technique to actually measure silica. Microscopic examination, as in ferrography, would pick up sand grains, but that'd probably be pricy.
 
If I were in your position, I'd just drive it and forget it. Only "remedy" would be to pull and rebuild the engine. Maybe dump the oil and filter.

If it really keeps you up at night, do a compression test, dump oil and filter, and UOA. If those three look even remotely normal, definitely forget the whole thing.

I had a forklift that broke its airhat stud. The throttle assembly and butterfly looked like it had been spray painted desert tan. Engine passed compression test. Dumped oil and returned to service. Later UOA came back OK. Been running around for hundreds of hours since then. No funny noises or behaviors.

Would never intentionally expose an engine to such things, but sometimes feces happens. Just carry on.
 
With only a slight amount of air getting through, I am betting that most stuff that got in got burned up and exhausted.
It will do you no good to worry. Just start taking care of it
 
Aside from looking at the intake, take a look at the MAF, that should be an indicator of how contaminated the air was. If you aren't getting any DTC related to the MAF I would think that the unfiltered air damage is minimal at best.It also depends on the environment that the vehicle was driven in. I seriously wouldn't worry about it.
 
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Originally Posted by pezzy669
Forgot to mention funny enough my prior '09 3.0 M272 had the "normal" main bearing knock on warm/hot starts with a quiet valvetrain, now my '11 3.5 M272 has no lower end noise but has valvetrain noise. As stout as the M272 is ('09 and later) I apparently just can't win with this engine line.

Forget the air filter, the biggest issue you have for your MB is that M272 engine. We had a couple of serious issues with our M272. Out of the 23 vehicles I've owned in my life, our bought brand new MB was one of the top 3 worst. And just recently I changed the oil on my friend's E-class M272. The valve train clatter was horrible.

Scott
 
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