Yes strange. My 99 550xl, 03 350xlt, and my 2011 350 lariat all have the insulation. But my '95 xl doesn't while my '92xlt in my field does?

As was mentioned before I too was always under the impression that it was insulation for sound? But if so you'd think it would be on all the diesels, whereas it seems it's mainly on the gassers?

 

all the new diesels are very quiet so for insulation for sound they would not really need it I can only go from what a different company used it for. ford might not use theirs as a fire blanket like Chevrolet but I could be wrong

 

its to increase the operating temp of the engine so that the engine meets emmission goals easier.

 

If that were the case, it would be on all diesels would it not? Gas engines warm up wayyyy faster. And if it was emission related, it would be on all of them, or atleast on all certain models. Not just some have it and some don't.

I'll stick with noise.

 

Seems like the hood blanket is on 2011-2016 Superduty gassers from XLT trim level and above. I think Ford uses it to reduce noise, but not in the way everybody thinks: I believe the hood blanket is used as a "Vibration Damper."

It's not on the diesels because the 6.2 can rev a lot higher than the 6.7. The higher rpms on the 6.2 probably cause the large area of the hood to resonate at certain frequencies. The insulation blanket is used to damp out the resonances and keep the hood from vibrating in harmony with the engine. I am betting that the 6.7 can't rev high enough to excite the hood harmonics, so it doesn't need the blanket. The blanket is a cheaper solution to solve vibration noise than designing a different hood for use only with gas-engine models.

I'd be interested to ride in an XL-level 6.2 truck without the blanket and compare the noises when the engine is rev'ed to a 6.2 truck with the blanket. I am betting the XL-level work truck "buzzes" a lot more when you stomp on the gas, or towing a heavy load up a hill with engine running continuously at 4500 rpm! JMO!

RWNJ