So I have had the issue of my IEW's engaging when not told to for the last 3 years. It was so random that I could go anywhere from 2 weeks to 2 months between the noise occurring. That was until I rotated my tires and was playing around with the vacuum lines a few months ago. After disturbing the vacuum lines I would get the noise every time I drove, but only when the engine was under a load while accelerating. As soon as I would let off the gas it would go away. After doing much research on here I assumed it had to be the IWE's.


The noise seemed to only be coming from the drivers side so I replaced that iwe first. Unfortunately I still had the same noise occurring as before. Before I was going to order another iwe for the other side I figured i'd do some more troubleshooting first. I bought a vacuum gauge and some fittings to take some readings at different points in the 4x4 vacuum system.


At each iwe I was getting approx. 22 in. hg. of vacuum. I was getting the same reading directly off of the main vacuum line going to my brake booster as well. It seemed as if I was getting plenty of vacuum. I then decided to attach the vacuum gauge between the check valve and the line that feeds the iwe's. I hopped in my truck and hit the road. any time I would accelerate the vacuum would steadily drop. if I would accelerate long enough the gauge would drop all the way down to 0 in. hg. of vacuum and the iwe's would try to engage at any reading below 7 in. hg. of vacuum.


At that point I decided that I would start with the simplest and cheapest parts first which were the small vacuum fittings and lines that connected the solenoid to the vacuum reservoir and the check valve.


low and behold after I replaced the check valve my issue is gone. I took it for a test drive after replacing the check valve and did everything that I knew would usually make the iwe's engage and I couldn't get them to engage.


here are a few pictures of the check valve as well as the top end vacuum harness.





I ordered the top end vacuum line harness just to make sure I didn't have a leak at any of the components due to me pulling the fittings on and off during troubleshooting. The harness comes with all of the 90 deg. rubber elbows except the one that connects the iwe's to the solenoid itself as well as the line that goes from the brake booster vacuum line to the check valve and the line that goes from the vacuum reservoir to the check valve.


When the parts came in I realized that the vacuum line harness also comes with a new check valve so the one I ordered separately will be going back tomorrow.


I guess I should have started with the cheapest parts first and then worked my way up to the iwe's. I'm just glad that it wasn't the vacuum harness that goes from the solenoid to the iwe's. That sucker was $91.00 from ford!

 

Outstanding write up and pictorial! Reps sent for a nice job!

 

My son had almost the same thing happen to the 2005 that I gave him to drive. They told us that both iwe was the issue and need to be replaced. Well they did that work and it still making grinding noises. So I bought the check value a put it in and bam it went away. I told the place the did the work and went and showed them what was the problem and to my surprise the refunded the money for labor that they did. I did have to pay for the iwe's but I got a year warranty with them only thing is if they go bad we have to pay the labor. LOL

 

thanks. I can only hope that this saves someone from the same aggravation I went through
at least they were nice enough to refund the labor.

 

I had the same problem with my 13 screw with 22000 mi. thought heat shield but found nothing. Took to dealer had my serv rep go for a ride with me, it took about ten mi. to finally duplicate the grinding. Gave me a rental, called next day and said it was the long vac harness and had to order from ford. Long story short three days later all is good again. He said he thought it was probably bad install from factory as it looked like it had been rubbing on something.

 

Just thought I would follow up on this. It has been roughly a month and my fix is still holding strong with not one single symptom showing up since.

 

THANKS guys,, I've got 2005 F150.... i have just replaced both wheel bearing hubs,,the vacuum hubs,,vacuum solenoid,,AND vacuum reservoir behind the battery. and i'm still getting the grinding/scrapping metal sound,on acceleration . gonna try the check valves. not ONE person i have been talking to about all this mentioned the check valves. thanks again!!!!!

 

I hope for your sake it is as simple as a check valve. But with that said, your setup is slightly different on your year model truck. If I recall your year doesn't have the vacuum reservoir(if it does, it's not in the same spot)and may have several check valves in the system under the hood.

Hope this helps.

 

I have been fighting IWE issues off and on since purchasing our 2012 F150 Ecoboost a couple years ago. IWEs were replaced under warranty (2 driver's side and 1 passenger side) and I replaced the solenoid myself. Starting to get IWE grinding noise again and would like to start with the check valve. Can anyone provide the part number?


EDIT: Looks like part number is Motorcraft YG-429

 

My dads '11 keeps busting lines. Haven't had an issue with the check valve.

 

Got info fr

om this site so thanks all. Pulled tire (hassle because cold and rainy) to access vacuum line. Tested lines and still unsure. Traced to firewall in engine compartment. Parts unavailable at major retailer and was going to price new with Ford. Stopped at wrecking yard with no tools and pulled these two parts for 10$. Replaced in a few minutes and rattle gone.
Check valve and solinoid.



Back firewall drivers side.

 

To the OP, I love to see Threads like this, Reps given
& FWIW, I too am a NRA Lifetime member

 

Thanks for the reps. I figure after how long it took me to find the problem and the amount of hours I had into changing parts/ troubleshooting what was a few minutes to post my findings on here. As I mentioned in on of my posts, I can only hope that this saves a few people some time and frustration when it comes to this issue.

 

Check out the write up in my signature I did quite a few years ago regarding the IWEs. Thread is still going strong. Although it was on a 04-08 generation its still relevant to these as well.

 

I recently had a similar problem. I replaced both IWE's and still grinding. What i found was a broken vacuum line on passenger side where it leaves the engine bay and comes into the wheel well.