Hi,
This week I have noticed a new sound from my '87 300d.
It appears to be associated with the throttle in that when I accelerate the noise increases and the opposite occurs when I slow down.
I have also noticed an increase in the odor of diesel at startup. Listening under the hood, the noise seems to be coming from the passenger side of the engine towards the front. But I am having a hard time pinpointing exactly where it originates from.
I've got 240,000 miles on it and is my daily driver. It still starts up in sub zero weather and I have not noticed any other ill effects other then the noise and smell along with a reduction in MPG.
I checked the fluid level of the transmission and it looks ok, I mention this because I was thinking that the noise may be reflecting off the noise reduction panel on the underside of the engine bay and may actually be coming from further back.
I would surely appreciate the opinion of this membership. I am worried that I may be listening to the impending failure of one of the systems. Could I be looking at a problem with the IP or something else in the fuel delivery system?
Thanks much.........
Glen

It sounds to me like your exhaust system has a hole in it. Most exhaust sounds are changed drastically with throttle and could amount to the extra smell of unburnt fuel. I had a little noise so I looked and didn't find much, a few days later my center mufller back where dragging. Shortly after I got that up the flex section failed, after about 6 months with a new downpipe I've had no problems with any of it.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

Jim, thanks for the reply.... I am going to check out the exhaust but I believe the noise is mechanical in nature. The car is making a wrrrring sound which is just barely noticeable at idle but does increase in volume during acceleration. At about 10,000rpm it is most noticeable, and everyone in my family has mentioned it. Doing speeds At highway speeds I do not notice it at all.
Hopefully I will get this figured out before I end up on the side of the road when it's a frosty zero degree's out.

On the up side, at least I was able to install a new hood pad this weekend which should make this car quieter and maybe make it warm up quicker.
Glen

Wow that is one fast revving motor, maybe it is your valves floating which you hear.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

While the turbo spins over 100k rpms there is no gauge for it and he hears it while not on the highway, generally the turbo is going at highway speeds so.... So what speed does the motor actually rev when you hear this? 1,000rpms?

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

Whirr can be alternator, PS pump, or turbo -- use a piece of broomstick or similar large wooden rod, but one end on the possible source (avoid the rotating parts, duh!) and the other behind your ear. Source will be obvious.

Fuel smell and low milage is almost certainly leaking overflow lines on the injectors or a bad return line (possibly suction side hoses, too, had to replace mine this summer).

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Unless it were a slipping belt I don't see how any of the power accessories change with the amount of throttle, sure they'll change with speed but the tone doesn't change with the amount of throttle.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

Yes, I did add in one too many zero's.....The noise seems more obvious when I first start out, so that would be at about 1,000rpm. But the noise is there at all speeds even faintly at idle.
I do have a turbo boost gauge and I'm getting 12 at WOT.
I have been looking under the hood and have not noticed any leaking diesel but will check out the return lines and see if that is causing or contributing to the smell.
I'm still going to drive it to work and back throughout the week and see if I can get lucky enough to determine what is happening before something fails.
It warmed up into the 20's this weekend but is expected to go back down to around zero for the remainder of the week. It's too bad that there are no electrical outlets where I work where I could plug in in order to make it a little easier on the engine.
Glen