Weird noise under light acceleration

[trunk monkey]

2018 max xlt with 4x4, 36,000miles.

I’m hearing a strange sound right at about the 1700-1900 rpm range. As I lightly accelerate I’m hearing (and feeling) a very fast vibrating sound that ends with a light thud...sounds like its coming from the passengers side front wheel area. It doesn’t do it all the time, so I haven’t taken it in yet.

Any ideas or suggestions? Thx

 

[JExpedition07]

IWE (Integrated Wheel End) or also known as a Vacuum Hub. Could be one of them or the check valve on the firewall. Next time this starts to occur switch to 4A and see if it subsides, if it does you know it’s in the vacuum hub system and can proceed to testing the check valve etc.

Commonly when the check valve fails under acceleration vacuum drops and the hubs partially engage. If a seal is going out on the vacuum hub itself it can do so as well.

 

[3tonsoffun]

2018 max xlt with 4x4, 36,000miles.

I’m hearing a strange sound right at about the 1700-1900 rpm range. As I lightly accelerate I’m hearing (and feeling) a very fast vibrating sound that ends with a light thud...sounds like its coming from the passengers side front wheel area. It doesn’t do it all the time, so I haven’t taken it in yet.

Any ideas or suggestions? Thx

Could be gearing issue as it’s looking for what gear to jump to, like on a bicycle where if your in between two gears it kinda grinds until it hits the right full gear

 

[aggiegrad05]

IWE (Integrated Wheel End) or also known as a Vacuum Hub. Could be one of them or the check valve on the firewall. Next time this starts to occur switch to 4A and see if it subsides, if it does you know it’s in the vacuum hub system and can proceed to testing the check valve etc.

Commonly when the check valve fails under acceleration vacuum drops and the hubs partially engage. If a seal is going out on the vacuum hub itself it can do so as well.

It’s this. There’s a TSB for it. Mine had it as have several others.

Easy fix under warranty.


https://static.nhtsa.gov/odi/tsbs/2020/MC-10171859-0001.pdf

 

[3tonsoffun]

The thud he hears makes it sound more like from the gear changing, dont think it’s hub actuators. Hub actuators are a humming noise, I’m thinking gear issue, just my opinion before y’all start hackling me about it since I’ve had and experienced failed IWEs twice now on my 16

 

[aggiegrad05]

The thud he hears makes it sound more like from the gear changing, dont think it’s hub actuators. Hub actuators are a humming noise, I’m thinking gear issue, just my opinion before y’all start hackling me about it since I’ve had and experienced failed IWEs twice now on my 16

When I had this issue it absolutely sounds like a grinding noise. So much so that I initially thought it was a tranny issue as well. The teeth of the hub rub against each other until they finally seat, hence the grind and thunk.

The system can’t pull a strong enough vacuum to disengage the hub, but it tries. So it half way disengages the hub. But then when all the air leaves the system completely, it engages and that’s the thunk.

I’d bet my paycheck on it. Especially as his is a 2018 (they corrected the problem for 2019+) and this is a well known issue. Whereas a hunting tranny causing grinding is not.

 

[3tonsoffun]

When I had this issue it absolutely sounds like a grinding noise. So much so that I initially thought it was a tranny issue as well. The teeth of the hub rub against each other until they finally seat, hence the grind and thunk.

The system can’t pull a strong enough vacuum to disengage the hub, but it tries. So it half way disengages the hub. But then when all the air leaves the system completely, it engages and that’s the thunk.

I’d bet my paycheck on it. Especially as his is a 2018 (they corrected the problem for 2019+) and this is a well known issue. Whereas a hunting tranny causing grinding is not.

Guess only way to find out is to throw it in 4hi and see if it goes away while it’s happening. Switch back to 2hi and if it happens again in 2hi it’s the actuators. Can Forscan measure the vacuum being pulled like a tuning device can?

If it is the 4WD system, I’d definitely start with the solenoid or check valves first. Cheapest and easier fix and probably what Ford will do regardless of their being a TSB until the problem presents itself again

 

[JExpedition07]

When I had this issue it absolutely sounds like a grinding noise. So much so that I initially thought it was a tranny issue as well. The teeth of the hub rub against each other until they finally seat, hence the grind and thunk.

The system can’t pull a strong enough vacuum to disengage the hub, but it tries. So it half way disengages the hub. But then when all the air leaves the system completely, it engages and that’s the thunk.

I’d bet my paycheck on it. Especially as his is a 2018 (they corrected the problem for 2019+) and this is a well known issue. Whereas a hunting tranny causing grinding is not.

When my 2007 had the vacuum hub issue (it’s been the same basic system since 2004) it at times would grind and clunk so aggressively it felt like I was running over a squirrel on a perfectly flat road. In my case it turned out my passenger side hub seal had cracked and was losing vacuum under acceleration. I’d bet his being an ‘18 is the check valve. Indeed a more common issue but an easy one to resolve.

 

[eatonmom]

I have the same issue. I didn't have it before they replaced my transmission due to 4wd problems. Now I have the grind/rubbing noise on shifting mostly from 1st to 2nd and 2nd to 3rd. Does that sound like what you are experiencing as well?

 

[aggiegrad05]

I have the same issue. I didn't have it before they replaced my transmission due to 4wd problems. Now I have the grind/rubbing noise on shifting mostly from 1st to 2nd and 2nd to 3rd. Does that sound like what you are experiencing as well?

Given your repair history, THAT may actually be a transmission problem. But I would think having them look at the check valve TSB would be a pretty easy trap to run before tearing into the transmission again. Good luck.