I HAVE A 2010 F150 SUPER CREW, 6 1/2 BOX, FX4, 5.4L, Have had a problem with chatter noises coming from front end. My mechanic has replaced the actuators, solenoid, checked the lines. Still have the chatter but much less now. He has given up. He said it is losing vacuum from the engine. Any suggestions? he said possibly the catalytic converters.

Thank you for any help.

 

How about the checkvalve?

 

yep. check on the checkvalve

 

I sat here wondering what the cats would have to do with losing vacuum. Then it dawned on me. There are heat shields around the cats that could be broken or loose causing the rattling. Maybe check around them, you wouldn't be the first.

 

Hes, it has been replaced.
I have vacuum on the box on top of the brake buster ( I don't know what it is. ) when the truck is off. short tube from solenoid to the box.

I went out and bought a vacuum gage to test the check valve. mixed results, don't know if i'm doing it right, i get vacuum loss on all three ports.
I'm going to try a smoke test on the lines.

 

It's not any lose parts.

 

The check has been replaced, I have my suspicions on the new one. can't get it to hold vacuum on any port. ( 3 port )

 

Take a look at the TSB in the thread I linked, it'll walk you thru what Ford recommends.
The box up by the booster is a reservoir to provide vacuum when the engine, at certain times, doesn't.
https://www.f150forum.com/f118/inter...2273-a-429040/

 

What about a crack in the vacuum box ?

 

the OP said he had vacuum there when the truck is off. So I don't think it's leaking, and the solenoid and check valve appear to be working correctly as well, or he'd be losing vacuum. I'm leaning towards a leak somewhere between the solenoid and IWE, possibly even an IWE seal, since I don't know how knowledgeable the guy is that replaced the IWE.