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  #1  
Old 02-17-2018
johnpa johnpa is offline
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Default JK 3.6 hat or no hat?
I just worked on my buddy Al's 2013 JK. Thermostat and belt, cleaned the engine compartment and was wondering what purpose the engine cover(hat) has? there was plenty of dust and dirt under the hat so that cannot be the purpose. I was wondering if by not putting it back on it would help radiate heat away from the engine?

any thoughts
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Old 02-17-2018
jgaz jgaz is offline
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Default Re: JK 3.6 hat or no hat?
I think they came into favor at Chrysler when we were owned by Daimler. Seemed to be a popular thing for European cars.

At the time I just figured it was strictly to clean up the “look” of the engine compartment when the customer opened the hood. But on some engines I believe it helps with the noise from the valve train and also dampens the “moan” that can heard in some engine intake manifolds.

OB1, you want to handle this one?
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  #3  
Old 02-17-2018
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dzJeepChic dzJeepChic is online now
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Default Re: JK 3.6 hat or no hat?
I think this is a great question; I wonder the same thing. I also think it's awesome you're helping Al with his Jeep chores. You're a great friend John.
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Old 02-17-2018
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squinko squinko is offline
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Default Re: JK 3.6 hat or no hat?
I don't think it serves any purpose other than keeping a little engine noise muffled and give the engine a clean look. Lot's of folks run without it and have had no issues.
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Old 02-20-2018
ob1jeeper ob1jeeper is offline
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Default Re: JK 3.6 hat or no hat?
Originally Posted by jgaz View Post
I think they came into favor at Chrysler when we were owned by Daimler. Seemed to be a popular thing for European cars.

At the time I just figured it was strictly to clean up the “look” of the engine compartment when the customer opened the hood. But on some engines I believe it helps with the noise from the valve train and also dampens the “moan” that can heard in some engine intake manifolds.

OB1, you want to handle this one?
Sounds about right to me Jim...
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Old 02-24-2018
Ladybug Ladybug is offline
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Default Re: JK 3.6 hat or no hat?
I agree with Di...Thanks for helping Big Al! You're a great friend!
smiles, ladybug
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Old 09-06-2018
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theksmith theksmith is offline
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Question Re: JK 3.6 hat or no hat?
thanks to this thread i decided to remove the "hat" on my JK's 3.6L as well. i added JohnPa to speed-dial in case i have any problems!



though, now i'm wondering if the dense foam on the underside of that plastic cover is not just acting as acoustic insulation, but rather an attempt to reduce the IAT (intake air temperature) by insulating the manifold?

first clue, the foam is thicker over the manifold and moulded to fit right against it...



second clue: there's a lot more foam around the manifold. both behind it and between it and the top of the head:



it seems the intake manifold is fully wrapped in insulation and the other side of the engine has none of this.

now i would never recommend anyone else remove all this foam. i'm sure the FCA engineers had a good reason for it, whether to reduce NVH or improve performance. however, i've become more concerned with engine temperature recently...

i just had to have the left head replaced on my 16 JK, and it seems 90% or more of the people with the similar misfire/head issues in the 2014+ JK engines have had the problem only on the left side. i was already thinking perhaps that side of the engine had a localized cooling issue because the intake manifold wraps directly over the head on that side, possibly trapping heat there. now that i found all this insulation, i'm even more convinced.

so... i removed all of the foam on mine in addition to the plastic cover.



i had to tear the portion directly above the head - there's no way to get it out in 1 piece without completely unbolting the manifold.

i save everything though, just in case i need to put it back! i couldn't hear any difference afterwards - but then again i have mud-terrains also didn't throw a code or see any major performance issues... yet.

thoughts?
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Old 09-06-2018
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Default Re: JK 3.6 hat or no hat?
Hoping for the best! I'd be white-knuckle, gauge-checker in that situation.
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  #9  
Old 09-06-2018
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Default Re: JK 3.6 hat or no hat?
If others are running theirs same way without issue I say go for it and see what happens. Could always get another one used on ebay
https://www.ebay.com/i/113209363254?chn=ps
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Old 09-06-2018
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theksmith theksmith is offline
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Default Re: JK 3.6 hat or no hat?
Originally Posted by scottL View Post
If others are running theirs same way without issue I say go for it and see what happens.
well that's the thing - i haven't seen anyone talk about removing the insulation behind and beneath the manifold.
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