Changed my air filter today and noticed the piece of silver insulation that was placed on the inner fender well had sucked into the airbox. I secured it back against the fender well, but when I checked the next day it sucked it into the air box again. I took it out (don't know why it was there) and threw it away. I also noticed on a 100 mile trip my mileage went up to 20 mpg. It had been 18 mpg. That insulation was really restricting the air flow

Very true. Everyone should check for this. My truck had this same exact problem. Had about 150 miles on the truck when I noticed, so I thought it left the factory as such. Mine was repaired my folding the insulation behind a piece of sheetmetal in the inner fender.

yep I have seen this on many trucks. I talked to one guy that said that tape/foil is used to help strengthen the fender, but I have a hard time beleiving it. Who knows though, I'm no body man.

It was there to prevent water from coming the air box through the stamped out spots in the fender. Its a good idea, but at the first sign of that thing coming loose, rip it out. Its gonna cause more harm then good

The same thing happened to me at about 150 miles. I drove all the way to Colorado and back with our 5th wheel trailer in tow. The truck didn't run worth a damn over all those hills. When I got home I found the problem and knew why it wasn't running so good in the high altitude.

For those of u that had the tape come loose, did it set the air filter minder or not?

If it was really restricting airflow it should be in the red and need reset, same as a dirty filter.

Just checked mine and sure enough it had pulled loose. It was loose over an opening in the fender so I just took and exacto knife and cut out that part of the insulation (about 2X4 inch piece) and made sure the rest was pushed against the inner fender.
Can't see where the part against the fender can do any harm, but the open piece may let a little more air in.
The air cleaner minder did not look affected at all, only showed about 5% red, and the air cleaner was still clean.

Is this piece inside the airbox? Does anyone have a picture?

Im not so sure the filter minder are the most accurate, considering what Ive seen in the past.

Maybe we should send this POST to GM. Maybe they could add more 3M tape or glue to the thing. Who knows, someone who owns a LLY might not have any auto knowledge or could be grandparents/wife/girlfriend and not fix it til its too late. Just a thought!


LATER !

Does anyone know how much water might get into the air box during a heavy rain and hard driving in it?

Does anyone know what kind of damage we may encouter with the hole not blocked?

Just something to think about as some readers may be going in there to take the thing out just for kicks. I went to see if mine was falling apart, and so far it is doing fine. I have 62K on my truck now.

NCMIC,

if you install any aftermarket kit there will be a much bigger "hole" not covered!
For real water crossings only a snorkel will help, otherwise I would not worry about it.;)

mahalkita,

i was discussing the hole that the fender wall will have in it. as i was looking on mine, it appears that lots of water would be able to get in between there and then sucked up into the air filter. as for an aftermarket kit, the air flow on those filters will be gathering air from around and different area. as for those of us that have the stock airbox in, the air flow comes striaght from the hole in the front of the box, which is directly in front of the area that is covered by the foil.

the question is that is there enough water that can cause harm if sucked into the air filter?

i guess i can run a hose on the front end to see how much, if any, water can get into the inner fender area. then run a test to see if any of it can get sucked into the air filter area. i just want to see if there needs something to be modified to keep a block on water and maintain maximum air flow on that area.

Just found out that you are running the infamous K&N filter in your stock box. If you really care about good filtration get rid off it and replace it with the original AC DELCO unit!

Thanks for the heads up...I will check it out tommorrow.