Trying to make the Benz a bit less noisy. - PeachParts Mercedes-Benz Forum

mbenzgoodyear · #1 05-11-2005, 10:06 PM

Dont get me wrong, there is nothing like the sound of the Mercedes Diesel, but was wondering if a few specific things would decrease the noise.

My benz doesnt have a hood pad, under the hood, and was pondering if purchasing and installing one would help cut the noise down. I know it would not be a dramatic decrease, but would this help and do I need the pad in the first place? And which pad is better, the one with the heat shield or without?

Also, and I am fairly certain, would having the valves adjusted decrease the noise as well or is the noise comming from the IP itself?

I have been putting ATF in the diesel and have noticed a slight decrease in the noise, and I know I cannot rid myself of it but was wondering if the above would help any.

I am thankful that I dont have one of the Ford or Chevy diesels (although I am sure they are great automobiles, nothing aginst them) that must be turned off when going through a drive thru.

DieselJim · #2 05-11-2005, 10:10 PM

Read the post I just put on about motor mounts and air filter housing mounts. Read that and check those also. That made a huge difference in my car.

pawoSD · #3 05-11-2005, 10:13 PM

The hoodpad does make quite a difference in muffling the clatter, mine didn't have one when I bought it, and both interior and exterior noise were significantly reduced when I put the new one in.

mbenzgoodyear · #4 05-11-2005, 10:23 PM

I had the mounts replaced about 2 weeks ago(forgot to mention that). That did help A LOT.

On a side note:
The Craftsman ratchet you mention is a great tool to have. If anyone ever asks what I want as a gift, for birthday and what not, I always direct them to the empty spots in the Craftsman tool chest.

turbodiesel · #5 05-11-2005, 10:40 PM

Nothing like the sound of a well running 617.. let it clank with pride!!

t walgamuth · #6 05-11-2005, 11:38 PM

all those things will help some but not that much. if the valves are too quiet thats a bad thing. if the diesel clatters at idle that is the optimum sound for power... my diesel fixing farmers tell me.

Brian Carlton · #7 05-12-2005, 12:02 AM

Now if you really want to decrease the noise...............yank out that 617 and install a 603.

Blissfully quiet at highway speeds.

I'm surprised John didn't tell you about this already.

pawoSD · #8 05-12-2005, 12:04 AM

We had a valve adjustment done on the '83 last week and it idles much more steadily and quietly now, runs great! I fear issues taking place in the rear driveline though, its starting to make strange sounds sometimes back there....possibly the diff/half shafts failing.

For some reason my car idles really quietly, I don't even know why, its always been quieter/smoother than the 83 even with its fresh valve adjustment....my last one was about 13k ago. I sure don't mind....but I have never been able to think of why....my only guess is that my injectors are in slightly better shape or something.

Old300D · #9 05-12-2005, 09:40 AM

Nothing mellows the sound of a 617 than 100% biodiesel fuel. The higher cetane and lubricity make it sound more like a sewing machine, no more knocking or clanking.

DieselJim · #10 05-12-2005, 10:59 AM

Once I fixed the mounts I just had that charactaristic thrum and rattles of diesels from that era. Reminded me of the chevy 6.2 liter diesel from 84 when it was in its prime. I suspect the only way to get rid of more of the noise is to insulate the engine compartment. I want to hear the engine. If you don't you risk your car dying before you notice that a cylinder is starting to lay out from a clogged filter, out of fuel or some other problem. Hearing the engine is a good thing and a valuable diagnostic tool. It just should not be obnoxious. Enjoy it and savor it. That and the fumes is part of the nostalga of these old diesels.

tenknots · #11 05-12-2005, 02:48 PM

One reason the 126's are so much quieter (I can barely hear my engine at 60) is the second firewall. I've seen them for sale somewhere for 123's but can't recall where.

The amount of time I spend in my car is the main reason I sold the 240D and bought a 300SD. A big difference

DieselJim · #12 05-12-2005, 07:59 PM

So the answer for him is insulation. Either find a second firewall or create a makeshift one or insulation barrier. That should help his problem

mbenzgoodyear · #13 05-12-2005, 08:04 PM

So insulation it will be.

I will order the hood pad, to help on the noise, all though it will not eliminate which is good. I like to be able to hear the Benz comming down the street.

I figure the hood pad can only help so why not get it anyway.

Thanks for all the suggestions, I appreciate it greatly.

Angel · #14 05-12-2005, 09:15 PM

I've been looking at this myself...

my 240D HAS a hood pad in very good shape (PO replaced it...), and its still is loud...on the highway at least.
Now maybe its becuase the motor is turning 3000-4000 (or more =) rpms, but I was wondering...

If I got some of the heat-resistant "dynamat" (or similar) and put it on the fender bulges (under the hood, next to the engine) would that cut down noise any ?
(I'd have to yank the motor to put it on the engine side of the firewall...?)

-John

pawoSD · #15 05-12-2005, 09:20 PM

The hood pad also protects the paint on the hood from the heat of the engine, which can damage it. I can drive for hours in the winter with 4" of snow on the hood and all that melts is the snow right up front by the grill...very well insulated. You can have your hand on it when the engine has been on for hours and its cool to the touch.

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