leightonen

I have an 09 F-150 King Ranch 4wd with 167k. I have been having a grinding noise problem for 2 yrs. In the morning, it takes 4 miles of warming before it starts to make grinding noise.The noise happens only at the low end of the gear during light acceleration. 20 mph and 1000 rpm, 30 mph ~1100 rpm, up to even 65 mph. It only happens on light acceleration. Letting off the gas kills the noise. If I put the truck in tow mode to increase rpms the noise goes away or is not nearly as loud. I basically drive in tow mode now to avoid hearing the loud noise. The noise almost sounds like a bearing rubbing. I took it to Ford two years ago and they replaced the sillenoid, two actuators, and the right inner axle bearing and seal for $1000. It didn't solve the problem. Then they said it was the transmission. Went to a transmission shop and they said transmission is fine. I currently have no engine lights on. I did have an O2 sensor error for a while but changed that. I figured something would have broken by now with that loud noise. Anybody have a clue what has been going on for 2 years?

Spiky

Does switching to 4wd change the noise?

leightonen

I believe it makes the noise not quite as loud in 4wd high. I haven't tried 4wd low. I can try both here in a little bit.

leightonen

I just tested it again. There is basically no change in noise when switching to 4wd high. I tried in 4wd low and it doesn't appear to make the noise because the rpms are too high and I didn't go very fast. The engine also shakes at times during this same low rpm acceleration.

Spiky

Well, that pretty much rules out one common noise.

leightonen

I played with it a lot more. Once I get it to making the grinding noise and switch to 4wd high, it does change pitch. It goes to a deeper bass sounding nice than it has while in 2wd. If I switch it back to 2wd, it stays with the deeper bass sound for a while. Once I slow down and get back up to speed it is back to the higher pitch noise that occurs in 2wd. Switching to 4wd high again changes back to deeper bass sound.

Blue2016XL

If I’m right, it sounds like you have an issue with IWEs. At least the hubs since they have been grinding for 2 years. Something is preventing the system from getting enough vacuum to disengage the front wheels. I’ve read it take 7 pounds of vacuum to keep the front wheels fully disengaged.

leightonen

I guess that is what Ford initially thought two years ago. They replaced the sillenoid, two actuators, and the right inner axle bearing and seal. When that didn't work, they wanted to change the transmission. Wouldn't that have fixed the problem if it was the IWE? Thanks.

Blue2016XL

One would have thought. However, did they replace the check valve? That alone has resolved it for at least one other forum member here. May have fixed mine but, the solenoide and check valve were replaced at the same time for me.

leightonen

Reading the invoice: "Checked 4x4 system for vacuum leaks. No leaks found. replaced 4x4 solenoid and right/left iwe solenoids. Replaced right front inner axle bearing and seal. Note: Has clicking noise from torque converter."
It doesn't sound like they replaced the check valve because they couldn't find a leak?
Appreciate you guys helping!