Oil change made all vibration go away?! - PeachParts Mercedes-Benz Forum

pawoSD · #1 05-04-2006, 08:22 PM

Ok here is the story, lately (the past 1,500 miles or so) our '83 300SD has been VERY rough at idle, heavy vibration (idle around 750rpm) but slight pressing of the pedal and it was gone. So today I just did a quick oil change and fixed a broken mount on the air cleaner (also found that the bracket snapped on one side.

) and now its in there pretty good on two new mounts and I tightened up the U-tube. After the oil change I fired it up, and it was running very quiet and smooth!!!!

How is that possible? It was like a night and day difference. The old oil was run about 3,200-3,400 miles or so, a bit over what we usally do (2,800) but a lot of it was freeway so that was why.

I really don't get it, sitting in drive at idle now (or in reverse) its perfectly calm.

It shook like a U-boat engine room before the oil change, now nothing....its mind boggling.

Any theories???

Furious D · #2 05-04-2006, 08:31 PM

It may have been the mounts you changed. The air cleaner assembly shaking around may have caused some funny vibrations. Other than that I'm not sure what it would of been.

Ara T. · #3 05-04-2006, 08:34 PM

An oil change fixed my inconsistent transmission shifting problem... one block the shift would be hard and the next one way too soft and slippery. After the oil change, perfectly solid but not too hard. Must been a vacuum thing.

pawoSD · #4 05-04-2006, 08:43 PM

Engine oil change or tranny oil change?

I did an engine oil change, just a new 1.7 gallons of Dino Rotella-T. The mounts were just the air cleaner ones....that cleaner assembly weighs less than 7lbs, could it shake the car that hard? The cleaner was really jumping around (since there was only one good mount). Seems odd...eh, who knows. But the vibration's gone!

(engine sounds smoother as well, it really does!)

deniss · #5 05-04-2006, 10:19 PM

hey whatcha puttin' in that oil?

barry123400 · #6 05-04-2006, 10:42 PM

It may just have been one of those odd coincidences but suspect you distubed something to your benifit when changing the oil or adjusting the air cleaner mounts. I know it's kind of hard to accept but shakey oil does seems improbable.

The only exception might be a bad batch of oil that would not hold it's viscosity and was far too thin perhaps. Or lost it's ability function normally. Something I have never experienced or heard of before although all products occasionally have bad or substandard batches. Anyways I think I see your somewhat transparent attempt to start an oil thread here.

I will not ask what oil you had in the engine that you drained either.

That would be like throwing fuel on a fire.

t walgamuth · #7 05-04-2006, 10:48 PM

i suspect it was just the air cleaner rattling.

they sound horrible when the little mounts are broken.

tom w

Hatterasguy · #8 05-04-2006, 11:03 PM

Placebo effect!

pawoSD · #9 05-05-2006, 01:16 AM

I drained out Shell Rotella-T oil and put in the same.

The vibration was not a sound, but a vigorous vibration that doubled as a complete body massage while sitting at traffic lights. I really have no idea why it went away.

Could the *oil* have done that? It seemed a bit thick when I drained it, probably ran it a bit long. Thing is...the oil only had about 1700 miles on it when the vibration began....it was a gradual buildup too, worse and worse...now...gone.

Engine was quite happy sounding with the new oil.......

Maybe if I had sent a sample of the old oil to blackstone they'd just send back an e-mail with a giant "!" in it.

biopete · #10 05-05-2006, 02:09 AM

Its just your good karma. And speaking of which, i have bad starter karma. Ishould have changed the starter this winter on the 300D when it ground (grrr) and would not start in the cold. These last two weeks , it finally left me hammering on the solenoid to get her going. So i go home from work monday and resolve to take the SD around until i get that starter out this weekend. Then running errands in the sd on wed. , guess what, its starter solenoid starts sticking. Tap, tap. I'm destined to replace a starter. And i'm gonna change the oil now while im at it. The sd shakes at stop lights.

Anyway, it will be interesting to see what precisely caused your smoothness but just keep doing what your doing.

pawoSD · #11 05-05-2006, 02:31 AM

Shaking is probably motor mounts or the rack damper pin needs adjustment.

I hope my starter survives for a while yet....I'll definatley be paying the dealer to do that job though when it finally does approach someday.

We'll see if the shaking remains absent.....hopefully it will. I also think we'll be doing oil changes at a rigorous 2,500 to 2,700 mile interval (I do on my car) so that might help some too.

MBeige · #12 05-05-2006, 04:33 AM

I didn't know the SD's also had self healing properties. That was usually relegated to the W123

You'd be surprised at what that air cleaner can do! The wagon's air cleaner is broken on the rear arm and it shakes noticeably. The sedan's air cleaner bracket is intact. It may only be a few pounds heavy but it's on top of the engine and when it vibrates, it has "good leverage" enough to shake the car (I suppose)...?

Ken300D · #13 05-05-2006, 09:23 AM

I had a loud harmonic vibration that went away when I replaced the missing nut in the center of the air cleaner housing. The cover was vibrating - loudly.

Ken300D

Jkid · #14 05-05-2006, 10:04 AM

Did you do anything with the throttle linkage while pulling out the air cleaner? Maybe you inadvertently adjusted the idle position so it idles just a little bit higher and therefore better. This happened to me after adjusting the valves. I thought the engine was stumbling more afterwords, I think I just lowered the idle a little bit though messing with the linkage.

Diesel Giant · #15 05-05-2006, 03:03 PM

Very weird, I see no connection.