So I've been having trouble with my 4wd on my 09 fx4. About a month ago the 4wd quit engaging so I took it into the dealer and they diagnosed a bad IWE solenoid and bad actuators on both wheels. I get the truck back after having them replaced and the 4wd shifts fine, however I have now started noticing a loud grinding noise under throttle (very bad when pulling a hill or towing) seems to be coming from the passenger side front wheel. I took the truck back in and had the 4wd looked at and they couldn't find anything wrong with the vaccuum system or anything. I'm at a loss. Could it be the wheel hubs causing the grinding? Im almost positive it is a 4wd issue because when I put the truck in 4x4 the noise stops.

 

If they changed a solenoid and both IWE's, you should have a 12 month/12k mile warranty on their work. Take it back and push them a little harder - that grinding is the IWE partially engaging under low vacuum conditions. There is something definitely wrong with the vacuum system and the new IWE is grinding itself up.

 

Yeah that's what I'm thinking too. If it was the hubs or something going bad I would think it would be making the noise all the time instead of in 4x2 under light throttle

 

I had an IWE go bad on my 05 after a CV joint replacement...

I bet they installed it incorrectly...if you look at the instructions for installing them it says to pull a vacuum on them during installation...I bet most people miss that one..

FWIW!

 

Could be a hole/tear in one of the vacuum lines. I had to replace an IWE and one of the lines on my 06. If i remember correctly the line had been rubbing around the upper control arm.

 

pull the line off by the Solenoid and do a vac test, see if it holds vac, if not it maybe the cross over vac line is leaking by the rack.

 

So I took it back to the dealer, this time to a different (and bigger) Ford dealer than the one in my home town. I told them everything that it was doing and it ended up being 2 bad check valves in the IWE system. All is well now thankfully. After much research, I was pretty sure it was the check valves because it was losing vacuum under throttle (which is what the check valves are there for) but I didn't have a vacuum checker and couldn't find one at any of the local parts stores so I figured it would be worth the $50 or so odd bucks to just take it to the stealership.