My three way blue check valve tests out fine. It works. When it does this noise, switching to 4A makes it go away. I have never had this happen before but I had the evaporator core and AC work done and now it's doing this. I don't know if it's related. How do i diagnose?
2013 Expedition front driver side grinding noise when accelerating
- Thread starter agford4x4
- Start date
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DeafBringer
Full Access Members
check the fluid in the front differential.
99WhiteC5Coupe
Full Access Members
You probably have a vacuum leak on one of the front IWE vacuum lines, or fittings. You will have to closely examine them, including the fittings.
If you just had major mechanical work done - I’d bet one of the lines was disconnected (and not reconnected) or damaged by the mechanic. They are plastic.
When you switch to 4A, the system the system engages in the front (no vacuum needed - default position without vacuum).
While in 2WD, the vacuum pulls on the IWE hubs, disconnecting the front drive. With a vacuum leak, the IWE is partially disengaging, causing the grinding noise.
Leave it in 4A while driving, until you can closely examine the vacuum lines (so you don’t damage the IWE hubs).
Good luck.
Welp, I found it!
The AC guys broke two of the IWE vacuum lines that run across the front of the frame between the wheels. In their defense, there was no way they could have known because I had to pick it up without a test drive and it was covered by wire loom/conduit. I ended up putting my air compressor into one end of the hose with teh truck turned off and putting 15psi of pressure in. I just listened for the hiss.
As I removed the split loom, the vacuum line broke into 4 more pieces. I ordered a whole new assembly.
We'll see.
The AC guys broke two of the IWE vacuum lines that run across the front of the frame between the wheels. In their defense, there was no way they could have known because I had to pick it up without a test drive and it was covered by wire loom/conduit. I ended up putting my air compressor into one end of the hose with teh truck turned off and putting 15psi of pressure in. I just listened for the hiss.
As I removed the split loom, the vacuum line broke into 4 more pieces. I ordered a whole new assembly.
We'll see.
The vacuum lines do get somewhat brittle with age, probably because of the cheesy plastic Ford used. Glad you found it.
Driver's side hose is fairly easy to replace, passenger side is somewhat more problematic.
Driver's side hose is fairly easy to replace, passenger side is somewhat more problematic.
