Remove the hood or not? I don't mind taking the hood off...it's putting it back on that I want to avoid!

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

I am interested in hearing how this works out for those of you that have tried it. I want the quietest change out there is.
John

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

It is not that hard to get the pad on with the hood up, folks have done it solo, a helper means you can't go wrong.

Put the hood in full upright position. Cover the engine compartment and fenders, cowl and windshield. Get the hood good and clean (a good scraping and degreasing if necessary), especially the edges. Test-fit the pad, so you can see where it will sit, mine had some cutouts, and fit under some of the sheetmetal, over other sections. Lay the hood pad down over the engine backside up. Spray half a can on the hood underside, covering evenly, especially the edges. Ditto for the hood pad.

Lift the center top into place and stick. Press the center line of the pad fully in place, top to bottom, then place the edges, then press out the remainder. Press, press, press all over.

Remove protective covers. Lower hood. Listen to the difference in sound as the hood latches shut.

Someone may know a fool-proof method of getting the hood off and back on in exactly the same position without a lot of effort. I don't. I wouldn't.

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Peter
1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K

I agree, I've done two with the hood still on the car. One by myself and one with "help" from my 10 year old. I used a little packing tape to make sure it stayed in place as I worked on it.

There are a lot of materials that will reduce sound and heat. The original (on my '87 124 and 201) are the waffle type with foil over the turbos, work pretty well. I wouldn't want to add a new type that would be significantly heavier, very un-German, especially if I didn't know what frequencies it is designed to dampen and what frequencies the engine puts out. Be sure that you have the under-covers if you're concerned about sound output.

A fair amount of engineering went into the sound abatement materials of the models from the '80s on, architectural as well as density and de-coupling materials. I'd side with OEM or OEM type just because it is a fairly good bet that M-B didn't skimp on the material and that they tuned it to the noise output in the engine bay. Look into an E320 D for some impressive sound-deadening, remember that if air can get out so can sound.

That having been said, I have used Soundown materials in my sound-blocking projects around Cat and Perkins diesels with very good success, and also the deep egg-crate SONEX stuff around diesel APUs. Some of the materials I've used are quilted with a layer of lead inside, ... how far do you want to go? JC Whitney also sells some of the foil/foam composite types, I've bought the 1" stuff in self-adheasive and non-adheasive and feel it did a fair job of isolating the big Cat engines from the outside world. The thinner single-layer foil/foam from JCWhitney might be adequate for the lower-frequency sound from the engine, waffle is better for the higher-frequency clattering etc.

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Gone to the dark side

- Jeff

My '82 240D doesn't have a hood-pad, or any evidence of ever having one, but then the hood may have been replaced several years ago after the PO's teenager had a fender-bender. I would consider adding a hood-pad if it would significantly reduce the roar I get inside the cabin above 60 mph. Or does the pad mostly tone down the racket one hears outside the car? Should I really be concentrating more on the state of the soundproofing in the doors, floors and firewall? Has anyone that installed a new hood-pad noticed any noise improvement in the cabin at highway speeds? The underside of my hood still has nice shiny matching paint so I'd rather not gunk it up with adhesive if I really don't have to.

Happy Motoring, Mark

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DrDKW

Mark,

Having recently driven a 240 from NY to Boston, at 70mph, with a new hood pad, I have to say I don't think I would worry about it. Those cars just rev high! You might notice a difference, however, I was comparing it to my turbo5.

Maybe some 240 owners who have tackled the sound issue can weigh in.

My wagon with a new hood pad is not really quieter on the highway. I was mostly worried about the turbo heat and my paint. I also fell into a free hood pad.

I think I am going to investigate soundproofing for the firewall.

Good luck

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Peter
1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K

My vote is for hood off. Just mark your hinge and bolt alignment before you do anything else.

Shove some heavy towels under the botttom crease--I did it solo several times when I was painting my car--but its beter to have a helper

Saturday I am going to the UPULLIT to study the hood pad designs on other cars. I will be looking at high end luxury cars. I dont believe the hood pad on the 300D is acoustically correct even though I am witless about acoustics and barely know how to spell the word. It is just too light and is more or less Peach Fuzz. I am going to try to find something heavier and stiffer and try to devise a better way to mount it. THERE must be a quieter solution....of course then again, you can olnly do so much 'cause the W124 diesel was so quietthat w/o a hood pad it even sounded like gasser...........

I marked the bolt positions, removed my hood and laid it on some padded sawhorses. Went back on with no problems. The hinge unit has hooks to hold the hood while you put the bolts back in place. I had my wife help me but if I were bigger/taller I could have done it myself.

Somewhere on this forum I have pictures posted of the job.

The pad keeps the hood cooler but makes no difference in noise, probably because the 123 doesn't have a belly pan.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I replaced mine for the paint issue I'd heard about. Put on a new pad, no difference in noise at all. I was bummed about it. But if you want to get one and want to spend less, you might want to go to a Pull-a-Part or something and get one in good condition for about $2 or $3. Rip it off carefully, it'll be fine to remount. Basically, you just use that 3M Yellow adhesive or better yet, the generic stuff for just $3 vs. $6 for the 3M brand. Squeeze some on as though you were putting up paneling in your house with some construction adhesive. Then press the pad up onto it, let it dry, and you're done. Easy.

1991 300d

...and it will probably fall off before your next oil change.

Forced induction is right. The hood pads age with the heat in the engine compartment. Compare a new one with the remains of an original one, you can see the difference. The material starts getting brittle and eventually turns to powder. You would be wasting your time looking for anything worth using at a pik-n-pull.

I doubt very much you could get a hood pad off cleanly even right after you put it on, forget after hundreds or thousands of engine hours. You will start seeing the center foam separating from the backing.

I'd be interested in alternatives to the oem pad, not so much for $$$ savings, but for sound. Carrameow, let us know what other solutions are out there.

ANd wasn't there some talk about bellypans for 123's, maybe euro versions or something??

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Peter
1985 300TD 4-speed 212K
1992 400E 343K
2001 E320 72K

Thanks to peterhardie, jeremy5848 and jbach36, I'm going to save myself the aggravation and expense of padding my hood, not to mention the additional rust-trap. I've seen a couple of W123s that had accumulated moisture in the pad and the hood actually rusted through from underneath! As I don't have turbo-heat to worry about, I'm going to concentrate my soundproofing elsewhere, including the firewall, doors and my recent repairs to the floor under both front seats that I haven't finished undercoating yet.

As for the sound system, I already replaced the PO's kid-installed defective CD radio, with an older Pioneer cassette unit and Pioneer 100-watt rear speakers, that I salvaged from a neighbor's trash last year. I have a lot of tapes and, so far, the Pioneer works perfectly, plus it has two big round knobs that I can find at night. The previous unit only had these tiny unlit buttons. Try one of those in the dark!
I also disconnected the monster audio cables (at one time the kid must have had an amp and boom-box speakers in the car) and reconnected the original dash-speakers and OE fader, which is helping to make the highway engine noise more tolerable.

Happy Motoring, Mark

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DrDKW