Might be just the turbo spinning. I know the turbo is on the other side but the sound could travel through...

__________________
dtf
1994 E320 Wagon (Died @ 308,669 miles)
1995 E300 Diesel (228,000)
1999 E300 Turbodiesel ( died @ 255,000)
2006 Toyota Tundra SR5 AC 4X4 (115,000 miles) rusted frame - sold to chop shop
2011 Audi A4 Avant (165,000 miles) Seized engine - donated to Salvation Army
BMW 330 xi 6 speed manual (175,034 miles)
2014 E350 4Matic Wagon 128,000 miles
2018 Dodge Ram 21,000 miles

My noise is barely noticeable at startup on a cold morning. It increases as the engine gets warm. While it is not what I would call loud, by the time I have traveled a couple of miles it is not easy to ignore. Not only is the noise present, but a sort of buzzing vibration is in the floorboard and even the accelerator pedal. It must just be resonance, because the throttle cable linkage under the hood doesn't vibrate. What causes me concern is that I first noticed the noise about a month ago, and it steadily grew louder for a few weeks. That is why I think I have a part about to fail.

I have isolated the sound. It is coming from some cooling lines starting just forward of the oil filter and running to the area at the bottom of the windshield washer tank. From there, I think the lines run to a cooler ahead of the driver's side front tire. I am still learning about this car, but I think this is an engine oil cooler. I can feel the vibration in the hoses (particularly at the clamps at the base of the washer tank). The vibration is strong at around 1500 rpm. I would be interested to know if anyone else who has noticed a whine in this model can feel the vibration in the same place. If these are oil cooler lines, is the source of the noise the oil pump?

E300nocash, did you ever find out anymore on isolating the whine you had? Did it center around the oil pump? I have the same thing going on, but subsides after a few miles down the road. I just got my 98 E300TD and it seems to want to do this in the colder temps. Thanks!

I haven't resolved it yet. I spoke to the local dealer, and the service manager said that he knew exactly the sound I was describing, and he had heard it once before on a 98 or 99 e300. They were certain the whine had something to do with the lubrication system, and were prepared to replace the oil pump under warranty (the car was relatively new). The owner moved, so he never replaced the pump. He said the trouble could be the pressure relief valve, but that is also with the oil pump. I have searched various forums, and I have seen maybe half a dozen similar posts to ours (but no clear answers). I think there may be a difference between your noise and mine. Mine gets louder as the engine reaches operating temperature (presumably because the oil cooler thermostat opens). I saw a post about a technical service bulletin addressing early 98 models with an oil pump whine or howl that is quieter after warmup. That seems to fit yours well. The cure was an upgraded oil pump. Although my noise increases with temperature, I wouldn't be surprised if the cure is the same. I changed my oil after only 2,000 miles, and I looked at the filter and ran the oil through a fine mesh screen. I didn't see any metal, so I am not as worried as I was that I am causing engine damage, but I am not giving up on finding the source. I hope someone reading the forum will be able to help us. If not, I'll be giving the dealer a crack at it since he had some familiarity with the problem.

I have a similar problem with my E300, although it only makes noise when hot. Lets say I drive the car, and turn off the motor, if I turn the motor back on lets say within 4 hours there is a 5-10 second howl that comes on immediately after startup. After 10 seconds the howl dissapeares and the car runs well. It never howls when left off overnight and turned on the subsequent morning.

Anybody have any resolution with the noise? I have a whining noise that has been getting louder that I've tried to diagnose the past couple of years. It is slowly but surely getting louder. Well described by original poster, "Jack525", and "e300nocash" regarding the various symptoms.

It starts from about 1000 rpm and gets progressively louder to about 2000 rpms (in all gears) and then is either covered up by other engine noise or road noise OR dissipates at that point. (Would dissipation of the noise at around 2000 rpm give any clue to what the problem is?)

Around that "magic" range of 1500-2000 rpm, pressing and releasing the throttle changes the "whiny" noise.

The mention of the Pressure Relief Valve piques my interest, as well, as it seems as if the throttle pedal has been getting even tighter than the normal MB tight and releasing the pedal in the rpm range causes a very noticeable change in the noise, as well. Don't believe it's the drive shaft or transmission as mentioned, it seems to go with engine speed in Park, Neutral, or Drive. It IS, however, noisier under load when Drive is engaged.

If the oil pumps needs replacing, what is the labor costs, i.e., estimate hours required (professional). From diagrams it seems that some engine disassembly is required. Thanks.

http://www.peachparts.com/shopforum/showthread.php?t=166261

I have had a few issues related to fuel leaks & air sucked into the fuel.
Changed delivery valve o-rings & copper washers.
Still have one leaky fuel line to go.

I have had some of the similar whine noise that you experienced. Hopefully can stop by the dealer tomorrow. I will post results after replacing leaky line and orings.

PMU

__________________
Phil
Previously loved
variety, but I miss the 99 F350 PSD- 37k, traded, damn

Current stable
98 E-300 TurboDiesel, 253k
http://www.facebook.com/people/Philip-Underwood/762882374

At least my engine is, maybe not me personally. I was waiting for colder weather to post the results (because the whining is much more noticable in cold weather, but with a warm engine). Since the topic has been resurrected, I will explain what I did.

I purchased two vibration damping mounts (MB part no. 201 504 02 12, $17.55 each) from the dealer. They are rubber cylinders with a coarse threaded stud on the bottom that screws into the frame rail and a machine threaded stud on the top for attachment of a loop clamp. The loop clamp fits around the oil cooler lines at the base of the windshield washer bottle on an E300. Both of my existing mounts were hard, and one was already broken. They were not difficult to access after moving the washer bottle, but the nut did not want to come loose from the top of the rubber (the insides just kept spinning). I had to drill out the top studs to get the loop clamps off.
The loop clamps have rubber cushions around the loop, and one of them had hardened and melted itself to the oil line. I decided to upgrade by getting loop clamps from McMaster-Carr that have silicone rubber cushions rated for 450 degrees F. I had to enlarge the hole slightly to fit the vibration mount stud, and bend the clamp a little to match the shape of the original clamps, but that was easy.

The whining/howling is less now. I can't feel the floor pan resonating at 1600 rpm anymore. I still don't know why the oil circulation system is so noisy, and would require such elaborate vibration damping, but mine is quieter now.

You've been hunting around the oil lines for some time and I'm glad you shared your success. I'm going to try this with mine and I'll let you know.

Due to a series of unfortunate events (fuel line leaks to start with) I had to have all fuel lines and fittings re-sealed/tightened. The MB dealer claimed they were getting a lot of diesels in for similar work ever since the low sulfur diesel fuel came out. Maybe it's not as thick as the old stuff or something. This work quieted the whine down quite a bit. On top of that, the engine had been groaning terribly and vibrating badly while idling. So I had the engine/transmission mounts replaced. This eliminated all the groaning and vibrating, and helped reduce the whine even more, to point where now, 50% of the time I don't even hear it, and the car has once more become a pleasure to drive. Of course, it's cold outside now and I don't know what's going to happen when it heats up in the spring/summer. City start/stop driving during hot summer months seemed to increase the engine groan and whine. So we'll see......... It may all be coincidence anyway, that the whine has been cut down. But when the weather warms up, I plan on checking out the oil lines too.

Ater E300NOCASH put on his new clamps. I ordered the same parts from Phill, but they didn't fit on my same year car. Don't ask me why. So I loosened the two under the washer and put non-metal washers under the ones I had. It made no difference and all whines have stayed the same. It really hasn't bothered me since I don't hear it at all once I get some road speed. With the really cold temps right now, it seems to last a little longer pending warmup.