VTX1800N1

How fast did the vacuum deplete when you switch from 2WD to 4WD with the engine running? You probably need a helper to operate the switch while you watch the vacuum gauge. It should go away very quickly. If not, the vacuum lines from the IWE to the solenoid could be partially clogged, causing slow engagement.

With brand new IWEs installed, and no noises in 2WD, the only other thing I can think of is slow engagement of the magnetic clutch inside the transfer case. Short of a fluid change fixing that, you would need the transfer case replaced or rebuilt.

JDaPP

Vacuum drops off pretty much immediately. I changed the transfer case fluid, but it is cheap so I will change it again and see if that makes any difference. I really appreciate all the help.

VTX1800N1

If the vacuum on both sides is dropping off immediately upon switching to 4WD and both the IWEs and Transfer Case motor are brand new, with the axle end bolts and IWE bolts all properly installed, the only option left is the clutch inside the transfer case.

VTX1800N1

I just thought of another possibility. If there is too much grease or anything else between the hub and IWE, it could cause the IWE to be slow to engage. This is actually more likely than the TC clutch having a problem.

JDaPP

Just wanted to follow up with an update. This is transfer case related. I drained the transfer case and put Mobil 1 ATF in this time (used Castro mercon first time). Now when I engage at speed it will usually go in without any issue. I say usually because every 1 in 4 will still grind. Unfortunately I am now in the process of moving so my Mom is going to take it back and figure out what she wants to do. I appreciate all the help.

MO-Ford

I had an issue last week with my 2008 F-150. Coming home from work in rush hour traffic, I heard a slight bang and then a terrible grinding noise. I couldn't tell exactly where the grinding was coming from. I immediately pulled off the side of the highway, and right before I came to a stop, a load bang again then the grinding noise went away.


It's June in the Midwest, high that day was in the 90's. I was at a loss.


I scoured the interweb and came across this site.


As this truck isn't my daily driver (I have a 2001 Ford Ranger to drive back and forth to the city) it has sat for a week until I could work on it. I started the truck this morning, switched it to 4Hi. The 4X4 light blinked then went off. I was able to get it into 4Lo however.


So, I re-read the initial post and how to diagnose this problem posted by VTX1800N1. I went through step by step by what was recommended. Went to Ford and picked up the IWE solenoid (the guy working behind the counter didn't know what I was talking about so I had to describe what it did).


$63 and about 45 minutes later, I had the solenoid replaced, the engine compartment cleaned and tidied, and was back in business.


So, the only logical thing for me to do would be to sign up to this great forum and personally thank VTX1800N1 for so generously posting how to diagnose and fix this problem. I had never heard of this issue before, and in my readings online don't think I have seen another 2008 mentioned with having this problem.


Sorry for the long post, but Thank You again VTX1800N1!

Doogie61

I allof a sudden had sporatic grinding in my driver side hub. Ussually only at highway speed, I changed out the solenoid for the new shielded one, now it is happening less often. It usually happens now when I am first starting out after it has sat for a while.I am thinking hose leak, but i could be wrong. I have only heard it in my Pass side once. When it runs for a bit the sound goes away, but does occasionally happen when driving after awhile. Am I missing something here without checking the entire system?

VTX1800N1

Nope, check the system as outlined at the beginning of this thread. The steps there will point you to any mechanical or vacuum problems.

Doogie61

Thanks, I'll start from the begining when i have the time. GREAT thread by the way, very informative and well put together!

xoman60

A lot to read on this thread. Some very good info. My 05 FX4 randomly locks the front end. The 4x4 light does not light up. It has not done it in 6 or 7 months but yesterday I drove it to work and noticed it was driving strange. When I got to work both front wheels were so hot I could not touch them. I'm sure when I finish reading all the posts a solution will present itself. Sounds like the solenoid though from what I've read so far.