Under hood insulation?

[jeepman3071]

I own a 2000 Jeep Cherokee 4.0L. My previous Jeep, a 1990 Cherokee, had an under hood insulation pad while my current one does not. I've also seen other vehicles that have under hood insulation pads. What exactly is the purpose of this insulation? Temp control? Sound deadening? My current jeep does seem to have a bit more noticeable valvetrain noise, but that could be anything.

 

[The motor guy]

I think it's both for fire control and also keeping heat away from the hood preventing paint peeling along with muffling noise. Some vehicles have them some don't. I don't think it really matters. You live further north so you probably don't get that hot during the summer. Id say 85 degrees max where down here in texas It's not uncommon to reach 110 in the summer. If your paint hasn't started peeling yet after 11 years then I wouldn't worry about it.

 

[cchase]

Many people are convinced it's for fire control. It's not, however.

 

[eljefino]

Fire control is an ancillary. The plastic rivets that hold the stuff up melt, letting an asbestosy blanket fall on the engine. On purpose or not is arguable I guess.

Seems to be something they include on the fancy version of many cars and leave out of the stripper one. Wish my wife's corsica had this; the 3.1 valve cover was probably 1/2 inch below the hood and the paint blistered right over it.

 

[Colt45ws]

Sound deadening. Nothing else. It may fall on the engine in the event of a fire, but it is too stiff to really 'coat' the engine. Itll lay there and...protect the hood I guess.
I removed it from my Vic the first night I got it.

 

[GMBoy]

Originally Posted By: Colt45ws
Sound deadening. Nothing else. It may fall on the engine in the event of a fire, but it is too stiff to really 'coat' the engine. Itll lay there and...protect the hood I guess.
I removed it from my Vic the first night I got it.



Why did you remove it? Seems sound deadening, keeping heat off the hood and trimming it out visually are all good things. Now you just see a plain steel hood.

 

[KrisZ]

I think it's for sound deadening only as well. My Mazda doesn't have one, but the more expensive version with 2.3 engine has it.

To be honest I'm glad my car doesn't have the liner. Living in the rust belt, the hood usually is the first one to rust, without the liner I can easily inspect and spray some rustproofing oil inside the hood.

 

[Kestas]

Mine are fodder for squirrel nests.

 

[Eddie]

+1 GMBoy.

 

[Colt45ws]

Originally Posted By: GMBoy
Originally Posted By: Colt45ws
Sound deadening. Nothing else. It may fall on the engine in the event of a fire, but it is too stiff to really 'coat' the engine. Itll lay there and...protect the hood I guess.
I removed it from my Vic the first night I got it.



Why did you remove it? Seems sound deadening, keeping heat off the hood and trimming it out visually are all good things. Now you just see a plain steel hood.


It is still painted. I took it out because I think its ugly and I prefer to hear my engine.

 

[mechtech2]

Like mentioned, the fire safety thing is pretty weak.
C'mon... how effective could this be?
It's pure luck if it helps in the right area and is adequate!

It is for sound insulation.

 

[ls1mike]

My 98 Z28 had it. My 01 Z28 didn't. My Trans Am doesn't either.
I do not care if it has it or not. My Buick and Truck do.
I don't get under the hood of the Equinox enough to remember if it does or not.

 

[01rangerxl]

Originally Posted By: eljefino

Seems to be something they include on the fancy version of many cars and leave out of the stripper one.



Yep. My '01 Ranger XL did not have any hood insulation. My '02 XLT trim Ranger does. The XLT has more sound deadening material inside the cab area too.

 

[jeepman3071]

Thanks for all the info. I had a feeling it was for noise. My previous jeep was the limited model while my current one is a sport which is more of an entry level trim. Guess its another way Chrysler saved 50 cents in some areas, haha.

 

[MarkM66]

Fuel mileage sites state it helps the engine retain heat, thus improving efficiency.

 

[IndyIan]

Originally Posted By: MarkM66
Fuel mileage sites state it helps the engine retain heat, thus improving efficiency.

I guess it might have tiny FE effect, a few degrees increase in underhood temps at most. The tracker never had one, I took the Neons out hoping it would be a heavy tar soaked mat... I doubt it weighs more than half a pound though. No increase in noise that I noticed and if its a tiny bit cooler under the hood, I'll take the .2 HP gain...

 

[rslifkin]

As far as FE increase, that would come from it taking longer to cool down, so if it sits for a few hours between trips, the 2nd one would be a warmer start.

 

[Kestas]

That's strange. All the automotive publications I've read write about how difficult it is for modern engines to shed heat. Things are packaged more tighly nowadays, putting a lot of stress on underhood materials.

 

[rslifkin]

^ In those applications, it's there to keep the heat from going out the top, as it would blister the paint on the hood. In my Jeep, the factory hood vents have almost no paint left on them due to the amount of heat that comes out of them. It just blistered off over time, as it's not high-temp paint.