So, I got a grinding noise under acceleration in 2wd the other day. Do all the tests, everything spins when it should and doesn't when it shouldn't. I don't have a vacuum tester other than feeling if there is vacuum, and there is on both sides. The side I think the noise is coming from does feel weak though. They both do honestly, compared to the top end portion. Put it in 4wd and everything is fine. Disconnect from the IWE Solenoid and everything is fine (how I am driving currently). I suspect there is a slow leak in the tubes or the res maybe.

It should be okay to drive on with the tubes removed from the solenoid until the parts get here, right? Won't be here until next week, I make 40 mile round trips daily. Right now I have them pulled and plugged with no noise while driving, so does that mean it's the actuators?
Does this sound like a vacuum leak? Only during acceleration and in 2wd only? I am wondering if it's the Vacuum Reservoir?

 

It is my understanding that loss of vacuum to actuators puts it in 4wd. So when its jacked up and in 2wd those axles should not turn if everything okay . I don't have 4wd I have just listened over the years. If you think you have vac leak a homemade smoke machine on you tube should show it up .
I am sure you will get better answers here soon . I made my smoke machine and its great for leaks .
I have heard water leaks on IWE solenoid is a big deal . There is a mod out for that .

 

Yea I did the FordTechMakeYouLoco Test with the truck jacked up and everything seemed just fine. Which leads me to believe it's not a vacuum leak and it's the actuators. Especially since plugging the hoses and disconnecting from the solenoid makes the noise go away while driving. Really confused by this setup and I dislike it very much. I'd just hate to spend the money on new IWE actuators, put them on, and have it not be the issue.

 

That’s because taking the vacuum away allows the IWEs to lock the front hubs to the front axle, and thus, no noise.

When in 2H, vacuum is applied to the IWE actuators, which releases the front hubs from the front axles.

When in 2H, if vacuum gets too low (like when under acceleration), the IWEs start to lock the front hubs to the front axles, but if they only partially engage you hear the noise, which is the teeth of the hubs and axles getting ground down.

IIRC, there should be a vacuum reservoir and a check valve to assist the vacuum when under load. The same vacuum reservoir supplies vacuum to the HVAC system, so a leak in the HVAC system may be reducing the vacuum available to keep the IWEs from trying to engage.

 

These solve all of those issues. I will install them in my truck next time rather than messing with trying to fix it.

https://www.rcvperformance.com/rcv-u...150-04-up.html

 

I see ,but what is the downside of permanently locking front hubs ??

 

I would also like to know this. Reduced gas mileage? I have not driven on a full tank yet, but I'll report back when I do. Would be optimal to drive on a couple tanks first, but I'd rather not if I don't have to. If I didn't need 4wd for the winter, I'd say screw it and leave it as is. But these IWE Eliminators seem like a much better investment tbh. Especially since it's only been roughly 40k and there is a failure already. That said, I highly doubt when the current ones are OEM.

But here is what I found:

Product Link:

Dorman IWE Delete

Dorman IWE Delete

You Tube

Seems like a little bit better option, and cheaper. Plus, it's available on Amazon and much easier to return if you don't like it. The only argument I see being made is about "wear and tear", which as we know, many vehicles already do this permanently. So I suspect the only difference would be in gas mileage. Either way, I am going to do it. Actually just purchased the Dorman version as I was writing this
Now I am wondering if there is a way to delete the whole vacuum actuator system. Probably just leave it there for the sake of simplicity.

 

If you plug vac to IWE solenoid I would guess its entirely out of the system . It would be nice to hear from guys who have done this mod . I see your point but I wonder if you already have some spline damage that you will have to fix first . Either way spline would have to be fixed .

 

The IWE eliminators fix that by removing the factory ones that have rounded off splines. If you’ve never had grinding, them simply plugging the vacuum line would achieve the same thing.

 

So I assume that if you have grinding and are doing the plug temporarily, you run the risk of slippage? Obviously I will inspect the hubs before installing, but the passenger side is a new hub replaced about a month ago. Kind of surprised that was not the failure side and initially thought I did something wrong. I suspect the drivers side hub will probably need replaced. I don't have any play, but that doesn't mean it's not bad. Thanks for the suggestions and any more input is greatly appreciated. I will keep you all updated. As for more info on people who have done this, there is quite a bit on other forums. Basically, I've heard nothing bad, so I'm going to give it a shot too.

 

Funny story...

I decided to re-diagnose everything and bust out the voltmeter this time. Turns out the solenoid was not getting enough juice. I replaced everything from the solenoid down, just because. Honestly, I did not trust those old vacuum lines. The only thing I can think of is that I did not do the initial diagnosis properly. Thinking back, I might have missed a step. Anyways, everything checks out now. I guess I won't be installing the lockouts and will be returning them.

That said, I did not drive on a full tank, but it did seem like a slight decrease in fuel mileage. I should have pushed it for a whole tank just to find out, but I was anxious to try and fix the problem. So... Everything running fine again, and 4wd engagement is nice and quiet as well as smooth. Much better than before. I did have an updated solenoid too. So not sure when it was changed before I bought the truck, but the IWE's were changed around 135k, so here is hoping they last the rest of the lifetime I have the truck.

 

Thanks for the explanation.

So, was the problem within the solenoid, or in the circuit supplying the “juice” to the solenoid, or the ground side solenoid circuit?

 

The problem was within the solenoid. I did not gather much information from videos online unfortunately, only thing I could find was the voltage should have been above 9 volts. Like I said, I did not find much info online and nothing was adding up to anywhere close to 9 volts with or without 4wd engaged, so that ended my troubleshooting and I replaced the solenoid. Tested everything and it checked out. Much better than before, no loud noise while engaging 4wd anymore either. Since I already had the entire vacuum line system including the two check valves and the smaller portion of the lines, I also replaced those. I'm definitely glad it was not an electrical problem beyond that because I am no bueno with electricity or diagnosing such issues and would have no idea where to start other than chasing wires and checking fuses. I didn't bother breaking out the haynes manual, but I suspect there is very little info in there about this system. I'd probably have to hunt for some TSB's - which I am also terrible at doing. I found so little info on this system outside of this forum and a couple other ford forums it's ridiculous. A couple diagrams of how the vacuum lines are setup and that's it.