Hoodliner and engine temperature

[Marcel Huijser]

I am going to follow Wanderlust's recipe "Dynamat Soundproofing Project" to reduce the engine noise of our 1997 E350 7.3L diesel. I wondered if the "dynamat extreme and hoodliner" might reflect too much heat back into the engine compartment. Some of the possible answers:

1. It doesn't have a significant effect on the engine temperature and it doesn't reduce the life span on the associated components. Just install the hoodliner.

2. It does, but you should also install heat vents in the hood to let the hot air escape more rapidly (... but then what does that mean for the noise I am trying to reduce?).

3. It does, and you just shouldn't do it.


Any experience?

Thanks, Marcel

 

[carringb]

Radiant heat through the hood will have zero affect on engine temps. I don't think there's any harm in installing it, other than I question if it would stay adhered under extreme heat soak (like stopping at a rest area while towing a heavy trailer).

I'm not sure you'll heat much noise reduction however. I don't think through the hood and subsequently through the windshield, is where your noise is coming from.

 

[Marcel Huijser]

Thanks!
Clarification 1: The hood insulation is only part of the sound insulation package. The other parts are the dog house, the floor, and the doors.
Clarification 2: It is the heat of the engine that may be reflected back into the engine compartment that I wonder about with the hoodliner; especially if that might cause more rapid deterioration of the plastic and rubber components under the hood.

 

[Twoxentrix]

I'm not sure you'll hear much noise reduction however. I don't think through the hood and subsequently through the windshield, is where your noise is coming from.

I'm inclined to agree with Carringb... Floor boards (front especially) & Dog house

 

[TomsBeast]

Just a quick thought... just after purchasing it, and after doing some work on my 7.3, I failed to get my doghouse positioned and latched very well. I drove it like this for months. Once I re-fit it, it got about half as loud. Fast forward to two years ago, I had a shop work on the boost tubes and fuel bowl fittings. They also didn't get it latched quite right, I pulled over and re-positioned and latched it on my way home. Once I replaced the latch that the shop broke, it got quieter again.



Still loud mind you, not like the whisper quiet V10 I once owned, but the dog house fitment has a huge effect on interior noise. Something worth checking.

 

[Marcel Huijser]

Thanks TomsBeast!

Yes, I will make sure the dog house sits well and is clamped on right. I also read that putting some silicone on the strips around dog house can help seal the dog house.

 

[Bbasso]

Imho most of the exterior motor sounds come from the wheel wells and reflection off the ground.
I've insulated two 7.3s and working on the 3rd now and while the extreme mats do reduce some but I'm not convinced that the $ is worth it.
As for insulation under the hood, it's double layer fiberglass and it does very well at keeping heat n sound in. I know because of my hood vents.

 

[upsidedown]

If you do any insulation under the hood I would think that something that absorbs sound would be the best consideration. Dynamat will keep the tin drum sound from happening on a metal surface but the hood is already fiberglass and probably does not create much of a tin drum sound when you give it a whack with your hand. On the underside of most modern cars/trucks there is a black felt material that is attached with plastic push pins. My thought is that this is in place to absorb sound as well as to reduce the temperature of the metal on the hood and prevent paint failure in a hot as hell area of the car/truck.

In summary, I would be interested to see if one of these newer car/truck liners on the inside of the hood could be trimmed up and attached to the underside of the van hood. Maybe that would provide some noise cancellation.

As mentioned earlier I think that the majority of the sound on the diesel engine in a van is transferred through the fenders and dog house and the floorboards and firewall. I would insulate and carpet these areas as much as possible. Big job but worth it. I did my van with Dynamat and added carpet and weathertech carpet protection mats with rubber backed carpet under the OEM carpet. It helped tons.

 

[Orv-SMB]

The heat radiated through the hood is negligible compared to the heat moved by convection through the radiator and out the bottom of the engine compartment. If you pull over after driving and touch the hood you'll probably find it's not all that warm. (It may get warm if you're stopped in traffic for a while, with little airflow.)

That said, my experience in cars is that hood lining mostly makes a difference in the noise people hear *outside* the vehicle.

I would definitely not put vents in the hood. You'll get hot air flowing out and into your cowl vents, making the A/C work harder.

 

[Marcel Huijser]

Thank you!

 

[allenl]

I've got another data point for you. I just insulated the doghouse with Dynamat Hoodliner, which I installed on top of the existing insulation. This noticeably dropped the diesel rumble inside at the driver and passenger seat.

 

[Marcel Huijser]

Great, thank you! Addressing the dog house is on our list. It is probably the location where engine noise insulation has the most benefits! But, since the freezer opened here in Montana a few weeks ago, I will wait till spring to deal with it... the glue doesn't like the low temperatures...