I have a 2011 F150 Supercrew XLT 4x4 with 202K miles on it (I bought it brand new, had 4 miles on it). It has been a great truck with no issues! However, recently it started making this rattling sound that was crazy sporadic and never predictable in what sounds like either the passenger front wheel area or maybe even directly under the motor. It may start rattling for a period of 1-3 seconds then stop for a long period of time then start again. It can happen at any time. Hitting a bump sometimes makes it happen or it could even do it driving down a smooth road at 70 mph. So I've been on a witch hunt trying to find it. Today, I started hearing it and I thought just for grins I would put it into 4wd while I was driving (doing about 30 mph) and instantly it went away. It didn't make the noise again until I took it out of 4wd. So I tried it several times and I'm completely convinced that is where it is happening. While driving in 4wd everything sounds decent (maybe a slight to almost unnoticeable hum at higher speeds of 50-60 mph) until I take my foot off the gas and allow the truck to slow down on its own. It doesn't vibrate the truck but it does make a very noticeable hum. Any ideas on what is going wrong? It may have to do with the lock in-out on the passenger front.... I'm just not certain where its at but that is my best guess....

 

It is the IWE.

 

Go read this thread. There is also a link to diagnosing the IWE system in post #133.

https://www.f150forum.com/f2/gen-ii-...c-pump-397377/

In short, changing the check valve is working for most. Solenoid could be the culprit also. Or both. Besides checking for a leak in the lines, those are the cheapest to try.

To confirm that it really is the IWE do this. Assuming it lasts long enough, while it is making the sound, switch to 4wd. If it goes away, it has something to do with the IWE.

If it doesn't, I also read that the brackets above the catalytic converters can make the same noise if one or both are loose.

 

Thank you so much for your responses! I read through the post in the link and as I think it is close it doesn’t sound the same as in the video. My noise happens in short bursts and it may also do it driving 70 mph or 10 mph. I think it could still be the IWE though. Any other ideas or comments?

 

When mine was doing it it was short bursts also most of the time. Sometimes it would be multiple bursts and every once in a while a longer one. Speed for mine did not matter either. Mine sounded like a paint can rattle when the ball is free to stir the paint inside or like a can was being dragged across the pavement at high speed.

Try the 4wd check if you can as this will confirm if it is an issue with the IWE system. Just be sure you are on a straight enough road to not put a lot of stress on the system while in 4wd. Switch back to 2wd as soon as you can as you do not want to be in 4wd on dry pavement for to long. If the noise continues then you have a problem with something else.

Also, check the brackets above the catalytic converters when everything has cooled off if it is related to the IWE system.

Read the thread linked to in post 133 in that thread. That will walk you through diagnosing the system and narrow down where the problem is.

 

Thanks again! It is definitely with the IWE as I was doing the 4wd check yesterday and it was confirmed. No noise when it is in 4wd. I really appreciate the info and the links.

 

You are welcome. If it were me, I’d do the check valve first and then the solenoid in that order. Those are the cheapest things to try besides doing a visual check of the vacuum lines from the IWEs to the check valve and then the solenoid.