Air filter housing cover

[Elizabetty]

When checking my air filter, I had trouble replacing the cover. The small separate plastic piece at the radiator sits in a groove and in addition to the main opening that blows into the box near the filter, there is a hole on top that appears would fit into a hole in the cover. Just past the filter, in the cover, there is another hole that another opening on the main duct would fit into, just beyond where it connects to the filter. Neither fits tightly. Wouldn't this would cause air to come into the filter housing, some going through the filter and being filtered, and some being blown around and going through the opening past the filter into the main duct and continuing on unfiltered? If the rubber on the hole in the duct isn't fitting tightly into the hole of the cover, it seems like unfiltered air could go right into that duct opening and continue on.

If this is correct, it may explain why I seem to have a lot of sand and grit when I removed the duct from the resonator after undoing the clamp. The clamp wasn't as tight as it should be, so I'm sure that's why some of the sand and grit could get out at the resonator for me to see it all around the edge of the duct where it connects. Seeing all of that dirt is what had me checking out the clamp and then the air filter housing etc.

While trying to piece this together, I noticed there is a notched area in the edge of the cover that would fit onto a raised notch on the top of the washer fluid reservoir. No matter how I try to screw it down with the raised notch of the reservoir fitting into the notched out area of the air filter housing cover, it doesn't come together. They simply meet up to each other and they fit as far as size but the lid doesn't seem to go down far enough to actually fit it together, or the reservoir doesn't seem to be up high enough. If it is supposed to fit in each other but doesn't, wouldn't that be sending more air into the air filter area since it's technically sitting higher and may have gaps?

1: will the rubber fitted openings on the two pieces of the ductwork in and out of the air filter cover not being attached to the lid firmly cause dirt to continue on in my system?

2: is there a tip to fitting them together when screwing the lid down? or do I likely have something warped and where would be a good starting point based on the notch issue from the washer fluid reservoir to the air intake cover notch? If I take everything off, I can fit the rubber into the opening of the lid. It's when I try to lay them in the top of the reservoir first and then meet the lid up to it that I can't connect them. Putting all three pieces back in at once without them coming loose is not an option.

3: perhaps the holes with rubber on the ductwork pieces are a shallow fit so the notch issue is actually what's causing the whole lid to be up too high and those openings to not snug tight into the cover?

I am supplying pictures I found online.

 

[Blckshdw]

You should have a little "snorkel" as I call it, that's like a curved funnel that sits in the grooves in the washer tank. The holes in the top of the filter lid are resonators, all they do is slightly alter the tone heard in the engine bay. There are a few of us that gutted the filter chamber by cutting all of that extra plastic out, making it completely hollow.

As long as the tube your filter connects to, fits snuggly, only filtered air will get to your engine.

 

[Elizabetty]

Thank you. I think this is solved other than a side note question. I'm happy to know no unfiltered air can make it through. Would the rubber on the snorkel and the rubber on the main duct not fitting into the resonators one day but fitting differently on another day if I was messing around cause some of my differing air sound under the hood? I think that could be assumed from what you wrote.

 

[Blckshdw]

I am one of the people that took a Dremel to my filter box, and replaced the plastic pipe with silicone tubing to get rid of all of the underhood resonators. Honestly, I couldn't tell a difference in the sound at all, so I don't think it really matters.

The only difference that I noticed, was the air filter now sees dirt over a much larger surface area with the extra plastic removed, compared to where it just enters the chamber from the snorkel with the resonators in place.

 

[Elizabetty]

So I learned the cover is just a cover and determined my main concern was that the opening in the air tube for what I was told is to fit in the resonator opening of the cover wasn't making good contact so there is the risk of dirty air going in directly to the tube and I've temporarily taped it off. The tape is completely wrapped around so there's no risk of it being sucked in if it were to come unstuck. There's no risk to this as far as I could tell.

My related question is in regards to the air filter box having a lot of dirt in it but the filter looking clean. My filter minder is pushing the 80% line so I'm still in the green but nearing the red and there's differing opinions on the necessity of changing at a certain mileage versus when the filter minder says to do it versus waiting until there are performance issues and it's actually visibly dirty ETC.

1: can my filter technically be clogged and that is why the dirt is gathering in the box versus going into/onto and catching in the filter paper? Perhaps it really doesn't have anything to do with being clogged and it's just normal to see dirt in it? 2: is there anything finicky with the 2002 trailblazer and air flow where a certain guideline applies for optimal performance?

 

[Mooseman]

Maybe it wasn't reset when the filter was last replaced? IIRC, it's reset by pushing on the top of it (they were eliminated after 02 or 03). If it's still at 80% after reset, I'd replace it. Maybe it's a crap filter or maybe has a lot of fine particulate. Maybe if you take it out and tap it, you might see some.

Sometimes you can have heavy dirt like sand just lay there in the box without actually getting sucked into the filter media.

 

[Elizabetty]

Thanks everyone. I can figure out reset and replacement if needed for the filter minder as well as the filter itself. As long as there isn't anything engine specific where this 4.2 is finicky on airflow, I'll proceed as the average Joe would. For some reason I thought I either saw a video or read somewhere that even though enough air is going to move through a filter that isn't fully blocked that the trailblazer can have fuel air ratio "annoyances" as soon as restriction gets a bit too high, often between 75% and up.