4wd actuators or vacuum line?

[Matticus]

2012 Expedition - I've been noticing a clicking/grinding noise from my front passenger wheel (especially when turning) and, after watching a few videos, have successfully diagnosed it as the 4wd being partially engaged. While diagnosing, I found the it wasn't just the passenger side doing it, but also the driver side. It just seems that the driver side was more noticeable. Neither side is super loud when the wheels are straight, but it's there.

My big question: Do you think both actuators are dead, or do I just have a vacuum leak in the lines leading to the actuators? When I pulled the lines of the solenoid, there was good vacuum up there, but I wouldn't know if it's enough. Today, I was going to check down at the wheels, but again, how do I know if I have enough? Any ideas on a good way to test?

Smaller question: How much harm can/is this causing? Should I stop driving immediately? Pop it in AWD and drive it that way until I get the parts in to fix it?

 

[BlackedOutMax]

2012 Expedition - I've been noticing a clicking/grinding noise from my front passenger wheel (especially when turning) and, after watching a few videos, have successfully diagnosed it as the 4wd being partially engaged. While diagnosing, I found the it wasn't just the passenger side doing it, but also the driver side. It just seems that the driver side was more noticeable. Neither side is super loud when the wheels are straight, but it's there.

My big question: Do you think both actuators are dead, or do I just have a vacuum leak in the lines leading to the actuators? When I pulled the lines of the solenoid, there was good vacuum up there, but I wouldn't know if it's enough. Today, I was going to check down at the wheels, but again, how do I know if I have enough? Any ideas on a good way to test?

Smaller question: How much harm can/is this causing? Should I stop driving immediately? Pop it in AWD and drive it that way until I get the parts in to fix it?

Check the 4x4 solenoid. If that’s faulty it will cause an air leak and the 4x4 gears will start grinding. It’s like $20 DIY. If that doesn’t work, put the truck in a lift and try to move the tires up down left right. If there is play, your hubs are bad. Sounds like IWEs from way you describe it but I always start small and check what I know I can first before taking it to a stealership

 

[Matticus]

Check the 4x4 solenoid. If that’s faulty it will cause an air leak and the 4x4 gears will start grinding. It’s like $20 DIY. If that doesn’t work, put the truck in a lift and try to move the tires up down left right. If there is play, your hubs are bad. Sounds like IWEs from way you describe it but I always start small and check what I know I can first before taking it to a stealership

In my second paragraph, I pointed out that I pulled the lines on the solenoid and checked that there was vacuum going through it (which there was) - is there a different test on that that you are saying I should try?
Good thought on the hubs, but I replaced both of those a few months ago and when I engage AWD, 4WD, or just have the car off, there is no click/grind when spinning the wheels. So, I'm about 99% certain it's a loss of vacuum somewhere in the 4wd system. Thus my question about driving around in AWD since it causes the click to go away by fully engaging those actuators

 

[coolzzy]

Pull the vacuum line down at the hub and use a vacuum pump Guage to draw vacuum. Let it sit for an hour and see if it leaks down and if so, you have a leak. There are a few one way check valves in the lines as well that keep the vacuum held when engine vacuum decreases. You can pull them and blow through them to see if they are still working one way.

You can also use the vacuum pump with a piece of vacuum tube to pull vacuum on the hub itself and see if it leaks down.

 

[coolzzy]

Oh and as a lazy alternative, unplug the vacuum solenoid on the firewall and let the front hubs lock in. As long as you are not in 4x4 it will not hurt the truck but might get slightly less mpg. This is essentially what happens when you go into 4a mode.

 

[Matticus]

Pull the vacuum line down at the hub and use a vacuum pump Guage to draw vacuum. Let it sit for an hour and see if it leaks down and if so, you have a leak. There are a few one way check valves in the lines as well that keep the vacuum held when engine vacuum decreases. You can pull them and blow through them to see if they are still working one way.

You can also use the vacuum pump with a piece of vacuum tube to pull vacuum on the hub itself and see if it leaks down.

I think this is the ticket. Did a bit of googling and found this at HF https://www.harborfreight.com/mityvac-vacuum-pump-39522.html
I think it will do the trick

 

[Matticus]

Boy did I get some odd readings testing for vacuum on the various 4wd parts. The vacuum lines themselves seem to sound. I pulled both lines feeding to the actuators and, through a series of plugging up and testing from various points, was able to get a consistent reading eventually. When I would first start to pull vacuum, it would bleed off a little, but then they would hold. Kind of confusing at first, but my guess is this has something to do with it bleeding the remaining air in the system initially.

However, the actuators themselves were more of a head scratcher. After pulling vacuum to the max the mityvac would go (around 23 inch pounds) the actuators would show they were holding vacuum, but not releasing. I would spin the wheels back and forth to see if they just needed a little movement to unbind them, but only got them to partially release once. So, I'm starting to suspect that, while the seals may be ok, something is binding up in them and they need to be replaced anyway. The new actuators should be here in a day or two, so when I pull everything apart, I'll be ready to put new parts on if necessary. I'm really worried I'm going to find that the new bearings/hubs I put on are toast due to the partial engagement that has been going on for who knows how long.

 

[nybandit]

I have the same issue with the noise. Sounds like a ratchet spinning round and round, not all the time though. Had a Ford Tech take a drive with me and he confirmed it was the IWE (or actuators). I replaced them myself along with the solenoid and checked vacuum lines, which seemed to have sufficient suction at the solenoid and at both actuators. Noise is still there so i have now ordered new vacuum lines, hoping that there is a hairline leak somewhere... ($58 on ebay).

When the tech drove with me and the noise started he flipped truck into 4A and smiled as the noise went away.... love the humor!

The vacuum is full time to keep truck in 2WD and is disengaged in all other modes - 4A, 4H, 4L, so the partial engagement of the actuators in 2WD is either loss of vacuum or bad diaphragm in the actuators... hopefully!

 

[Matticus]

I replaced the actuators...boy did they need replacing! I think the vehicle sat in/drove through some really muddy water. The actuator diaphragms were fine, but really gritty and wouldn't compress all the way. This explains why I they were holding vacuum at the actuator, but not releasing from the hub completely. After that, I then found that the vacuum line on the passenger side was really brittle and cracked easy and also clogged with dirt. So, after replacing that also, my problem was solved. That little vacuum pump from Harbor Freight was really helpful and worked great. At around $32 (if you use the coupon), it's a great tool to add to your collection.