Hood liner or sound insulation

[Esteban]

Thanks for your efforts bmw1racer. Agree that the 135i would be hotter. Maybe someone with a 135i and the liner will do a similar test. (hint hint) lol

[tock172]

Originally Posted by Esteban

Thanks for your efforts bmw1racer. Agree that the 135i would be hotter. Maybe someone with a 135i and the liner will do a similar test. (hint hint) lol

I just happen to have a laser temp probe too, hmmmm...

[Esteban]

Originally Posted by tock172

I just happen to have a laser temp probe too, hmmmm...

Hah! I was thinking of you Alex when I wrote that.

[bmw1racer]

Originally Posted by tock172

I just happen to have a laser temp probe too, hmmmm...

Cool... Then you're all set.

[Olgeezer1]

Originally Posted by gjm120

probably not much while driving but I'm sure it retains heat longer after stopping.

I think you're right and that's the part that keeps me away - heat retention. Reading some Mike Miller re: all those plastic parts, plastic cooling system etc. and high underhood temps. - not conducive to long life. Where possible I pop the hood after running to help with cool down and prolong the life of all that plastic. Don't see the liner being helpful in that regard.

[The Wind Breezes]

Originally Posted by Olgeezer1

I think you're right and that's the part that keeps me away - heat retention. Reading some Mike Miller re: all those plastic parts, plastic cooling system etc. and high underhood temps. - not conducive to long life. Where possible I pop the hood after running to help with cool down and prolong the life of all that plastic. Don't see the liner being helpful in that regard.

Are you an engineer or materials expert? I'm not, but I do have extensive experience with injection molding and 3d printing so I know how plastics respond to being heated and cooled. Being hot is not what actually damages the plastics. Besides, your plastics will get hot anyway as an intrinsic feature of operating your engine and driving the car. The plastics will expand and contract as they heat and cool, and the more rapidly they do this, the more stressed they will be. Differential heating and cooling, where the plastic doesn't heat or cool uniformly is the worst kind of stress. If anything, you're EXACERBATING the problem by popping your hood. As for me, the hood liner went away a long time ago because it muffles the pretty noises. I just drive the car and deal with the consequences, which will come about whether you pop a hood or not.

[gjm120]

If you're going to open the hood to hasten cool down, I don't think the liner is hurting things. Whether a quicker or more gradual cool down is better -don't know what I think about that.

My view is all sorts of plastic, gasket, seals are going to go on the car sometime too soon to please me (including the water pump). Maybe the hood liner moves that day closer by x yrs or y miles. But at least my hood won't age much quicker than the rest of the body.

[KNS]

My neighbor and I both have E46s. I've owned mine from new and he bought his a year old. I've always tried to do the right thing for my little 325i and it has paid me back with wonderful reliability.

Anyway, I've always popped the hood on warm and hot days when getting home to help cool off the engine compartment (be nice to all that rubber and plastic...). Like most people my neighbor does not.

One day while he was working on his car I noticed the flexible rubber trim above the headlights (only seen with the hood open) - they were dried out and crumbling, little pieces had broken off. They looked like crap and really needed replacing. The same trim pieces on my car were (still are) soft, flexible and completely intact. The car is 13 years old with 213,000 miles.

[Stubbie Blue]

I got a hood insulation pad from AliExpress for $33:
https://www.aliexpress.us/item/3256805457134608.html

They ship it folded up so it will be creased so don't buy it if that will bother you.

It came with some 'Christmas tree' style clips but I also bought some that look like the BMW ones for $3.46:
https://www.aliexpress.us/item/3256804320429806.html

The tabs around the sides were a bit too large to go into their holes but I managed to just squeeze them in.

First impressions are that it cuts out the high pitched whiny sounds from the engine, but the sounds under hard acceleration are still fine. On my 2012 135i, I also had to remove the foam under the N55 front and rear engine covers because it had disintegrated, so this hood insulation may make up for that.

I can't really tell any difference in temps as there's only an oil temp gauge, which is about the same as before.