Today I realised that my engine air filter had been improperly installed. One of the clips of the covering was not closed properly. I think its because I didn’t unscrew the intake pipe while installing and the pressure caused it to come off. It could have been like this for some Months as that’s when I last looked at the filter. The after filter part of the intake should have no dust however I found the after filter housing had quite a bit of dust so I guess it’s been going through the intake for some months.

I know that dust and debris can damage an engine and my question is not about this.

Im wondering how can I know to what extent, if any, the incoming dust/debris may have reduced engine power.

Unless you guess by feeling I guess the only way to know is if a compression tests shows inconsistent compression, or a dyno shows less power than should be, would I be right?

And if the results for both of these are near normal/or healthy would it mean that whatever dirt has gone through has not caused any real damage and there shouldn’t be provided the intake is clear from now on?

1 Answer 1


The air filter prevents foreign matter, both large and small from being sucked into the engine and possibly causing damage. If something large had entered, it likely has passed on through after being crushed and burned. Smaller matter like dust and dirt are more likely and have almost certainly make their way in due to the mis-installed air filter.

Did that cause engine damage? Almost certainly there has been some at this point.
Is it a major concern? Probably not, at least in my opinion.

Short of major diagnostics or a tear-down for inspection, you probably can't assess any possible damage. I suggest that if the engine is still running normally, you should just continue driving it at this point as any "fix" will be exceedingly expensive (i.e. a total rebuild or an engine replacement) and you don't know that such a thing will ever actually be needed.

The best thing you could do currently is to install the filter correctly, perform an engine oil and filter change, and then stop worrying about it.

  • Are you saying that even if there is engine damage caused by dust, it can still run normally I.e. performance can still be normal therefore a dyno would still show normal results? Commented Sep 20, 2019 at 13:50
  • I'm saying that it depends on the extent of the damage. If, however, this is a vehicle used for racing (and your dyno comment leads me to think this may be the case) then you are obviously looking to run the engine near the limits of its capabilities. In that case, you may want to do a teardown/rebuild or just replace it. All bets are off in this scenario.
    – jwh20
    Commented Sep 20, 2019 at 16:50
  • But if the damage is minor, which I think is likely, you will probably not ever notice it under normal conditions.
    – jwh20
    Commented Sep 20, 2019 at 16:58

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