Does a Hood Blanket really make a difference? - PeachParts Mercedes-Benz Forum

Carrameow · #1 11-26-2006, 05:55 PM

My 85 300D has new (expensive) tires and a well tuned engine and you can barely feel it shift. Road noise is low and the engine purrs like a kitten. The new chain and valve adjustments and new mounts and rehung exhaust(my custom design with a special Heavy Spring flex arm that comes off the transmission to replace the steel bracket Mercedes uses --took it off an EDG that was scrapped at work) exhaust make a difference. I also replaced the rubber thingies on the pilot shaft. and stuffed wads of noise killing insulation into my dash when I remounted it.)The car runs like its fresh off the line.

However I have no hood blanket. Having spent quite some $$$ on this car this year, I have to turn off the faucet sooner or later...the tires, believe it or not, were my best sound reducing item. Road noise is very very Low.

Would a hood blanket make that much a difference?

TheDon · #2 11-26-2006, 06:05 PM

a hood pad would cover all the underhood skeleton and make it look cleaner/factory ...

#3 11-26-2006, 06:08 PM

It cuts down on noise. Some claim it saves the hood paint from the heat.....

BTW, that Euro W123 250 looked like it never had a hood pad from the factory.

peterhardie · #4 11-26-2006, 06:20 PM

I have a california version turbo diesel, and the lack of a hood pad has burnt (discolored) a 2" spot on the hood paint, there when I got the car. I put a pad in after I had cleared up an oil leak that was spraying the underside of the hood.

I have the high turbo, as opposed to those with the turbo under the air cleaner, so that may make a big difference. On cold days, with frost on the hood, I can drive a lot farther now before that frost disappears. I'd say the blanket/pad was soaking up heat that is otherwise cooking your paint.

I can't tell how much noise it absorbs from the cabin.

MTI · #5 11-26-2006, 06:28 PM

At least for the W201 turbo diesel, the OEM hood pad had a foil section above the turbocharger to insulate from the heat.

In addition to noise reduction and thermal protection, the pad is supposed to be a flame retardant, provided it's not soaked with oil.

bgkast · #6 11-26-2006, 07:28 PM

The W123 turbo hood pad has the foil section as well.

Hit Man X · #7 11-30-2006, 01:00 PM

If not for sound, do it for looks...

Carrameow · #8 11-30-2006, 02:21 PM

I have done some advanced engineering research on reducing hood acoustics which I will describe below. The conclusions I reached were astonishing and I was invited to Stuttgart to give a demonstration of my experiments below which I am revealing for the first time. To achieve 2 to 3 dB of engine noise reduction at a ambient temperature of 57 degrees Celsius and an atmospheric pressure of 14.699987 psi with ambient humidity of 57.56% . No specialized sound measurement or reduction instrumentation was used as the conducted trials made use of the human year and qualitative judgement (Ref : Volume 1, Mercedes Stuggeten and Lars pages 102 to 109 2002 Berlin Stuttgart Press) The initial step of this proof is to throw open your hood as your first experiment to get a baseline measurement. Doesn't your engine sound louder? Note this on a 8.5 x 3.5 index card. As your next experiment find a material in your house such as the new down comforter your wife just bought and fold it to the size of your hood and throw it in there and close the hood. Run the engine for at least half an hour. Now doesn't your engine sound doubly quieter. Again, note this on an index card. As your third experiment, finally reach for something even thicker, such as the nice Persian Carpet on your hardwood floor. Now throw that on top of your down comforter and slam the hood and slam the hood again and run the car again for say an hour and a half. What will you hear now? Nothing! Why? Because you are Dead as your wife has probably killed you.

Mark DiSilvestro · #9 11-30-2006, 06:49 PM

Quote:

Originally Posted by Hit Man X

If not for sound, do it for looks...

Well, I like the shiny, painted underside of my hood. Of course this hood never had a pad, so I don't have to look at ugly dried blobs of old pad and adhesive.

Happy Motoring, Mark

peterhardie · #10 12-01-2006, 07:14 AM

It would probably be a waste to put block heaters in cars doing taxi service in Cairo. The bean counters at MB got involved and decided to cut a step out of the assembly process.

There are guys (MB sales reps??) who will swear that they can start their car down to 0 degrees F without a block heater. I am suspect, having had two wagons which ran fairly well, and were maintained well, and would not start below freezing without a lot of coaxing and getting up earlier in the am without a plug. My current wagon only has 160K (the others were over 300K), and it was a tech's car, so it is uneventful in winter now. If I know it is going to be below 20F and don't want to gamble, I plug.

I have found that an eight-hours-cold engine will fire easier than a twelve-hours-cold one. Sometimes I will go out at 11p and run the car for 30 mins if I know the am is going to be frigid. It helps.

ALSO: if your battery is over 5 years old, get a fresh one with the most cranking power you can find. And like it or not, the starters on mine have needed refreshing; age slows their cranking speed. I plan to at least bench test mine at 200K. I put new ones in my previous wagons and it made a difference. Cold diesels need good starting rpms. Clean air and fuel filters, and a valve adjustment covers it. Keep your favorite diesel additive in the tank for gelling.

Which reminds me to put the extra extension cord in the wagon!

peterhardie · #11 12-01-2006, 07:22 AM

...and many great ideas start out as idiotic. The remaining idiotic ideas are "learning opportunities!" Don't ask me about heating solvent to clean a carburetor.

I actually like the heat gun idea, never thought of it. Of course, my heat gun is buried in a drawer somewhere (reminder: put that in the car too!).

On slowing heat loss, you might be right. Couldn't hurt.

Someone needs to do a test with a temp reader, starting with a hot engine on a 0F day, block readings every hour. Anyone have one of those remote temp guns??