2012 5.4 3 valve 99k fully serviced, sound like Model T when under power

[LexpeditionKy]

2012 5.4.3 valve, 99k miles. Fully Ford tech serviced. Timing kit, plugs, head gasket , hoses belts, bearings, steering rack etc at 55k. Heater hoses, fluids etc at 99k. No codes or drivability issues.

A sound like a Model T accelerating (puckita puckita) intermitantly happens after its warmed up. Only while my foot is on the gas pedal or when the cruise control is doing same. Lift foot off pedal and sound goes away. More noticeable on road driving or when concrete is close by to echo the sound. In general it often makes me think I'm being passed by a diesel truck.

Only obtuse thing is this vehicle has never dripped condensate from the AC drain. AC always works great front and rear. I am gonna get the drain looked at but there is no gurgle or mildew smell.

I am gonna take this to my Ford mechanic that is the only person I let work on this truck. Besides me changing the oil and air filter.

Ideas?

 

[ptguy0618]

Dude. You have no idea how identical to my issue this is. It's been driving me nuts for a while now. Ive got a 13 with 97k miles on it. I had asked for my shop to listen for the sound and check it out before, but they couldn't hear it. For me, its after the engine is warmed up, and the engine is under load. I notice it most when going slightly up hill for some reason. But when i am passing a close building or wall you can really hear it. I tried explaining it to my wife that it sounds like an old timey black and white movie when a car engine putters out when you see it breaking down and steam coming out of it, like a puttering metal noise. Please let me know if you get any feed back on this!

 

[twodollars]

If your not having a driveability or power issue, I'd be leaning towards exhaust leaks, prob at manifolds. Worse when cold and when engine is under load. Something to check anyhow.

 

[LexpeditionKy]

Here it is 9 months later and the chugging noise isn't isolated! I found it almost never does it around town. It did do it bad pulling my boat at 70 on the interstate in the mountsins of Ky. And this time I felt it twice in the steering wheel! No codes, no check engine light.

I'm going to try and get a mechanic to look at it. My main mechanic is no longer around. aarrgghh

 

[LexpeditionKy]

2012 5.4 3 V XLT. 103k miles. April 2026 and the problem is solved! I was having no luck solving the odd sound of a Model T I was hearing. Took it to several mechanics. Most couldnt hear it. No codes. Read original post about sound. So I had a master brake cylinder fail from being 15 yrs old. While thats being replaced the calipers, pads ètc got done. That mechanic said the sound was resulting from dry cracked front hub vacuum hoses leaking. Causing the axles to tryi to engage. Tested. Solved!!!

 

[17expi]

2012 5.4 3 V XLT. 103k miles. April 2026 and the problem is solved! I was having no luck solving the odd sound of a Model T I was hearing. Took it to several mechanics. Most couldnt hear it. No codes. Read original post about sound. So I had a master brake cylinder fail from being 15 yrs old. While thats being replaced the calipers, pads ètc got done. That mechanic said the sound was resulting from dry cracked front hub vacuum hoses leaking. Causing the axles to tryi to engage. Tested. Solved!!!

Yes, the little metal splines were trying to slide together. Luckily the hubs didn't get ruined. It would never throw a code either.

 

[LexpeditionKy]

May 4, 2026. Im still waiting on vacuum line parts. But in the meantime the mechanic capped off the vacuum port. This let both front hubs engage the axles. So the front axles are free wheeling in 2WD mode. No sound heard any more! Engine runs better without the vacuum leak too. Test succesful.

Just a note. All these vacuum lines connect to a valve at the brake booster. Thats the valve that locks or unlocks the hubs from the dashboard switch. The hubs are engaged when there is no vacuum present. Proper amount of vacuum disengages the hub from the axle. And in my case I had enough vacuum to disengage until the motor was under load....then dropping the vacuum level, causing the hubs to attempt to engage while driving.

While the vehicle is in for work I'm getting shocks, both radiator hoses and new Michelins.

 

[17expi]

May 4, 2026. Im still waiting on vacuum line parts. But in the meantime the mechanic capped off the vacuum port. This let both front hubs engage the axles. So the front axles are free wheeling in 2WD mode. No sound heard any more! Engine runs better without the vacuum leak too. Test succesful.

Just a note. All these vacuum lines connect to a valve at the brake booster. Thats the valve that locks or unlocks the hubs from the dashboard switch. The hubs are engaged when there is no vacuum present. Proper amount of vacuum disengages the hub from the axle. And in my case I had enough vacuum to disengage until the motor was under load....then dropping the vacuum level, causing the hubs to attempt to engage while driving.

While the vehicle is in for work I'm getting shocks, both radiator hoses and new Michelins.

That won't hurt anything being engaged but the front diff and driveshaft are spinning and causing a slight drop in mpg, plus a little wear on everything up there. Some people leave them engaged (for some reason) but it's a bad idea.