I have been noticing a rattle that comes from the exhaust only when I accelerate. I hear coming from the passenger side only. I know that it is not coming from under the hood, so that is why I narrowed it down to the exhaust. Any help would be great!

 

This might be a number of things, but it could be as simple as a heat sheild rattling.
I'd suggest crawling under the truck, when it's not running, parking brake on, and when the truck is cool (like after sitting all night) and begin tapping on things with your hand/fist, or a dead blow mallet. Something will rattle eventually.

Welcome to FTE and good luck.

 

Alright Thanks, I will see what I can find.

 

I went under to take a look and see if anything would budge. No luck with that approach. Do you have any other suggestions?

 

When does it happen? Only on acceleration? Doesn't rattle when you're coasting or coming to a stop? Doesn't rattle when you're on rough terrain?

If it only does it under acceleration, you could actually be hearing the engine "pinging". This is predetonation.

 

It seems as if it only does it during acceleration. Would the sound of the engine "pinging" be the same as a knock or actual metal hitting metal? This sound really sounds like an exhaust type sound, so this has got me baffled. If it is the predetonation, what do I need to do?

 

A muffler will do that. Something inside comes loose and it will rattle under acceleration.

 

You may have a Cat. convertor that is starting to break up.

 

I agree with Millzy. I had the same noise on my Jeep, sounded like ball bearings in there. The CAT was coming apart inside and after a while the check engine light came on indicating that the cat was not functioning properly. One thing to keep in mind. When they do start to break down, small pieces will come out of the tail pipe on when you gun the engine. The thing you have to be concerned with (and I have seen this) if too big a piece breaks loose it can block the exhaust and then things get bad quickly. I've seen the entire exhaust pipe from CAT to manifold glow cherry red because it was blocked. This my friend can and will catch something on fire. Don't ignore it.

 

Is this truck 4wd? If so, next time you hear the noise, flip it into 4wd & see if the noise stops & post back with results.

 

My truck is 4WD. I tryed the method of switching to 4WD and the noise did stop. I switched back and the sound returned. What do you have in mind?

 

I too thought about this when you said it happened during acceleration. I believe you have a problem with the IWE's in the 4wd system.
Here's a thread to read through:
https://www.ford-trucks.com/forums/8...then-some.html

 

My 2006 F150 4WD had the same symptoms. I ended up finding the vacuum line going from the RH IWE, across under the radiator to the LH IWE was cracked & the IWE's weren't getting enough vacuum under acceleration to stay disengaged. Time to start checking vacuum lines on yours.

HTH

 

Does your rattling happen within a certain RPM range when accelerating? My 07 has a rattle that sounds like a loose heat sheild but I have checked anything that could be loose under the truck and nothing seemed loose or would rattle. My rattling only occurs between 2.6 and 2.9k RPM. It has rattled since I bought it last year and since then I have installed a Magna flow CAT back. I will also look into the vaccum lines as earlier posted (I just replaced my vaccum valve for the 4x4 three weeks ago).

 

Mine does the exact same thing. If you hold it at that rpm it keeps on doing it. Let off or accelerate and it stops. Drives me crazy. Its not pinging. The heat shields are all good but its hard to check around the manifold area. I just figured it was a heat shield, could be the a/c compressor or a pulley? I've had pulleys make some funky noises. This is an issue that cant seem to be replicated when the truck is sitting still. That makes it extremely frustrating and very hard to diagnose. Its embarrassing when people ride with me, especially with so many Government Motors people around haha.