Kind of a weird one, but I notice a weird sound at speeds over 60mph which sounds like it's coming from the base of the windshield. Sounds like someone is knocking on the base of the windshield. Has anyone experienced this? My Dodge Ram made a similar noise...WTF? No biggie, just a little annoying when combined with my speedo rattle!

 

maybe something that fell down the cowl vents? or a loose windshield wiper assembly?

 

I've seen very similar noises being caused by a car bra or those plastic deflectors that mount at the front of the hood -- what they can do is set up an aerodynamic "ripple" that starts slapping the windshield at certain speeds. If you have anything like that mounted up front, try pulling it off and driving the truck.

 

I actually do have one of those deflectors on my hood...good call, I'll try pulling it off. Bought the truck with it, not sure exactly what it's good for anyways.

 

Correct me if im wrong but i think those deflectors deflect the wind over your windshield so when your going high speeds bugs get caught in the wind current and just fly over your windshield so you don't have a huge mess.

 

Maybe the 'fresh air' / 'recirculating air' door is loose and the negative pressure at the bottom of the windshield (effect may be amplified by a bug deflector) is causing the buffeting noise you hear?

 

I was a windshield installer for 5 years, and am in the process of starting with another company. If your truck is a 90 like your sig says...go out and grab a plastic spoon or something similiar(so you dont scratch paint or risk chipping the windshield) and see if the cowling is lose(thats the part under the shield where the wipers stick out of)... we did a lot of those with loose cowlings and loose lower chrome trim around the base of the shield. Especially if the shield has been changed before, it ends up making the bottom chrome trim get stuck in the urethane we use to adhere the shield and eventually, as the clips to the chrome rot and break the chrome gets held on (Very loosely because the surface of the trim is not prepped with a chemical called an activator for the urethane) just by the urethane in a few spots, giving it room to rattle. More than a few of those, the trim and cowl came right off still stuck to the old windshield. So just see if it's lose or not. If it is, gently cut away any urethane clinging it to the glass with a razor blade and either pick up new clips at a dealer or get more urethane(from a home depot or lowes) and stick it on better. DO NOT USE SILICONE! I can't stress that enough, 1 it only holds at up to 50psi which is insufficient compared to the 3000psi that certain polyurethanes can, and 2 it absorbs moisture like a sponge causing any metal around it to rot very quickly. If you need to buy urethane make sure its a hot applied adhesive non conductive kind. To heat it up just throw it in the oven at 180F degrees on a cookie sheet for 20mins and you can apply it with a regular caulking gun. It will take about an hour after applied to start curing, and it cures faster in the cold as it cools down and absorbs moisture faster. So use a body tape or painters tape to hold it in place. And it fully cures in 24hrs, so leave the tape on for a few hours atleast. Please try to use as little as possible, maybe a hershey kiss shaped glob every few inches on the trim, as if you use a ton...its gonna make it terrible if you ever need to have someone change out the shield. Wear gloves when handling the chemicals, and any urethane that oozes out can be cleaned up with a razor once its hardened if its on the glass, and pulled off slowly once its cured on metal.

 

Edited to be more readable (did my best, don't hurt me [much]):

 

Thanks guys!

 

Couldn't stand my huge mass of words eh? Thats fine. I should hire you as my copy editor. Like I said, I was a windshield tech for 5 years. Before that I was an infantry Marine. I'll admit grammar and placement were never highly stressed key points. Looks alot more professional now lol.