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  #1  
Old 10-15-2002, 04:58 AM
John_Schwarz
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'95 E420 - Vibrations in Steering Wheel at Idle

Hi,

I've spent about 6 hours going through all the posts trying to coming up with a short list of possible causes, but I haven't found any posts describing a similar problem. So, here is goes...

Before this started, if the car was in Drive or Park, you barely knew if the car was on. There were no vibrations in the cabin nor the steering wheel.

When in drive or park, there is a vibration easily felt through the steering wheel. It has varying degrees. Sometimes you it is not there at all (about 5% of the time). Most of the time it is noticeable has oscillates from not too bad to very noticeable in 2 second intervals (think of a sine wave). Other times it is much more noticeable and can be felt in the seats, gear selector and you can hear it too - like the timing is off and exhaust has more of thumping sound.

Often when coming to a stop at a red light, the first couple of seconds, there are no vibrations. After a couple of seconds the the oscillation cycle starts.

On occasion (maybe every 4 to 6 weeks) the cars shakes alot when first started - this last for 30 seconds at the most. Happens more frequently when it is cold outside.

Electrical load makes a difference for a couple of seconds - for example, if all the electrics are off and then I flip on fan, then headlights, then stereo, etc. there is a spike in the vibrations, but the goes back to the usual range of vibration after about 2 seconds.

If you are really tuned into the vibration, you can feel it in nuetral or park, but it's much less than if the car is in Drive or Reverse. It's very faint in park or nuetral, but the car goes from vibration to a subtle rock or kick every couple of seconds. Put the car in drive and it sounds like you put front wheel drive 4 cycle japanese econo-box into drive.

The car has 95k miles; at 86k miles (Nov. '91) it had the transmission replaced and motor mounts. The vibrations were occurring before this repair and continued afterwards. At 90k miles it had its schedule service. Every 2 to 3k miles it gets a bottle of techron.

I bought the car about 2 years ago and did NOT have any of these vibrations. they started last summer and have gotten alittle worse - meaning, occurring on a more regular basis, but but the range of the vibration is about the same.

Seeking suggestions and order to ruling out causes - I don't want to spend $2k only to find out a $50 part replaced at the started would have solved it all!

Thank you very much for your input. John.

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  #2  
Old 10-15-2002, 01:05 PM
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Join Date: Dec 2001
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It sounds to me like broken motor mounts.

In Nov. 2001 (you typed '91, though, which is impossible), you had the transmission and mounts replaced. Were these the transmission mounts or the motor mounts?
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2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".
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  #3  
Old 10-15-2002, 01:14 PM
John_Schwarz
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Yep - the November '91 would be impossible! Ooops - it was late. I pulled the receipts from MBZ and it states the motor mounts were replaced, so I'm guessing the transmission mounts were not... So, they are "officially" on the list to be checked. After reading alot of posts, here's a list mounts I've come up with:

Transmission Mount
Engine Mounts -- repalced already! - maybe defective?
Engine Shocks -- applicable to w124/E420?
Rack Dampner -- applicable to w124/E420?

Anything you would add or remove from the list? Thanks, John.
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  #4  
Old 10-15-2002, 03:00 PM
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I would say this is definitely the engine mounts - I had the same vibration on my '93 S500 and new mounts cured it 100%
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  #5  
Old 10-15-2002, 04:15 PM
John_Schwarz
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Hi Andy,

The motor mounts were already replaced in November 2001 - and made no difference.

As I go through the chronology, if any of this starts sounding too familiar to anyone, please provide input/suggestions.

UPDATE SINCE YESTERDAY:

The car went into the shop this morning; after a test drive and speaking with tech for about 20 minutes, we're going to start with cleaning the fuel injectors. This would coincide with the general recommendations of BG 44 (I think I got that right) or the Penzoil Fuel System Cleaner.

There is a slight miss-fire every 30 to 60 seconds (noticeable when just sitting in Park or Nuetral). The tech said is was probably variances in the fuel pressure psi. He'll also try cleaning the throttle body alittle; he is very hesistant about going into the throttle body since that is an expensive part.

Also, the car has a serious mis-fire every 4 to 6 weeks when first started (last for about 10 to 30 seconds); this suggests that one or more fuel injectors is losing pressure or is blocked.

I'm hoping cleaning the fuel injectors works, but I am doubtful. This might be one of several problems, but I don't think it is "the" issue. The car always gets it gas from Chevron and a bottle of Techron every 2 to 3k miles.

When I check-in this afternoon, I'll ask about the condition of the vacum hoses. I want those replaced anyway.

ITEMS RULED OUT:

The wiring harness was ruled out because the timing issues are very subtle and there are not any of RPM spikes or stalls noted by other owners.

Flex-disc only applies to when the vehicle is moving - vibration should ne noticeable around 35 to 38 mph. Mine is smooth as silk.

WHAT'S NEXT:

If this doesn't cure the vibrations, then we'll look at the transmission mounts, motor mounts (again) and engine shocks. Before doing this, I will try the Penzoil Fuel System Cleaner; people have had good results, so another $8 is cheaper than a cup of coffee at the service shop!

GENERAL INFO ON E420 / W124 VIBRATIONS

As for the vibration itself, if the engine was in the S-Class it would not be noticeable because the additional size and mass of the vehicle would better absorb the vibration. Whereas with the V-8 in the E-Class, the chasis easily transmits/transfers any engine vibration.
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  #6  
Old 10-15-2002, 07:27 PM
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My money is on the motor mounts.

A slight miss a big sign of a bad engine wiring harness, especially since so many are bad between '93 and '95.

Have your tech examine the wiring harness for cracking insulation.

I don't know why he's focusing on a fuel supply / pressure problem, which doesn't seem characteristic of this at all.

I would have focused on an ignition-related problem - a bad plug, plug gap too small, but probably a bad spark plug wire, or a short at the spark plug wire resistor "boot" or end. A bad connection at the resistor boot would be my guess for the missing, if the engine wiring harness is fine.
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2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".
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  #7  
Old 10-15-2002, 08:56 PM
John_Schwarz
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Hi Suginami:

MOTOR MOUNTS:

The car was purchased 2 years ago and did not have this vibration. The vibration developed about 9 month laters. At the one year mark it had the transmission replace and the motor mounts replaced. After the repair, the vibration remained unchanged. So, unless the old mounts failed and the news ones were equally defective from the time of install, they are not the cause.

BAD PLUG, GAP, etc.:

About 3 months ago the car had its 90k mile service including replacing the rotors, caps, plugs, etc. No difference from before to after.

WIRING HARNESS:

During the 90k tune up, the harness would have been removed. One would expect the movement to cause additional stress on the cable, thus more cracking of insulation etc. Thus if there was a slight problem before, it would be even worse afterwards.

But, I won't totally dismiss the wiring harness yet. Called MBZ and gave them the VIN; the are looking up the history to see if it has already been replaced. If not, hopefully they will honor a parts replacement. I'm alittle doubtful; I've had alot work done Mercedes Benz of Bellevue, but they've left me less than satisfied, so I have not been there in about 10 months.

NEXT STEP:

The car is supposed to be ready this evening. I'll take a long test drive and see if there are any changes after this work. If the problem is there, then onto checking a couple such as the vacum hoses and fuel pressure check. If all that checks out, then back to the wiring harness and alittle exploratory surgery.

The tech doing the work seems to know his cars; most importantly he has felt the vibration I'm obssessing on, so at least he knows if the problem has been fixed or not.
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  #8  
Old 10-16-2002, 01:35 PM
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Is there a steering shock on your car? My 92' 190E 2.6 had one that needed to be replaced and caused a vibration up thru the wheel.
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  #9  
Old 10-17-2002, 04:32 PM
John_Schwarz
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Hi Jim,

Yes there is a steering shock (or dampener); that was replaced alittle over a year ago as part of front suspension maintenance check.

Update to the car's status:

After the fuel injectors were cleaned, the slight mis-fire (about 45 to 60 seconds) was fixed. This is NOT the problem though, it was just another little issue. This mis-fire was very, very slight. It would barely cause a ripple in a glass of water. The engine ran smooth before, now the response is even smoother. A love that engine!!!

For those you who have suggested the mounts; the tech checked all the mounts and said they were okay (there's more on this, read on). Also, keep in mind, the motor mounts were already replaced last November.

Some more observations about the vibration - in drive, the car idles at 500 RPMs with very little variance. With my foot on the brake, if a nudge the RPMs up to what looks like 550 RPMs, it goes away most of time. However, that throttle point you can tell there's more stress on system than usual. The vibration is gone, but the car just doesn't sound like its usual, happy resting point. Next, there is a slight, gentle shaking around 1100 to 1200 RPMs when the car is in nuetral or park. Finally, the vibration I'm ranting about has a 3 second cycle - while idling at 500 RPMs in drive, the vibration oscillates about 20 times per minute. Meaning, the vibration hits its high and low points 20 times. That's not 20 thumps, it 20 periods. I'd say there is probably about 20 to 30 little pulses in each period. That's really hard to count!!! So, it could be an exhaust vibration transferred through chasis at some point. - This is just my opinion and I'm not tech.

So, what's next...?...

This Monday we will pull one belt off the car at a time to see if the compressor, power steering or alternator are the problem. I doubtful about this because if they were the problem, I think the vibration would be same whether the car was in gear or not. However, we need to eliminate some variables, so what the heck.

Next, the exhaust will be loosened and then re-tightened will the car is on the rack (the type where the tires are NOT hanging in the air). On similars models they have seen problems where exhuast is slightly out of alignment, thus stressing the drive-line and created a vibration. This may have some merit; on occassion a weird vibration/rattling sound comes the tail pipe area when the car is first started (last around 60 seconds).

While they have the car in the air, any other mounts passed the motor will be checked again, and I'm leaning towards replacing them. I want them ruled out 100%.

Next, the wiring harness does not appear to be a problem. The idle is stable, there are no weird kicks or hic-ups under acceleration. However, we're cutting it open to take peek. And, those vacuum hoses are going to be checked.

All this will be done in my presence (they expect 2 hours) and I'll be the one saying whether the vibration is better or worse as we change or check eacy item.

FUN FUN FUN! If anybody has anything we should add to check list, please let me know before Monday. Thanks a million.
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  #10  
Old 10-17-2002, 06:00 PM
John_Schwarz
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After going through the invoice when the transmission was replaced, the transmission mount was also replaced (Thanks MB Doc for helping with part numbers). So, the motors mounts and transmission mount have been replaced within the last 12 months. The vibrations was the same before and after this work, so it's doubtful they were contributing to vibration.
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  #11  
Old 10-17-2002, 08:14 PM
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I am very interested in the outcome of your search for the source of the engine vibration. I too have had a engine vibration that fits your description. I have had this vibration in my 95 S500 since it was around 45,000 miles, and the car currently has 62,000 miles. I have brought the car to the dealer on many occassion without success. These are what was replaced: Engine mounts, plugs and rotor, reset computer fuel injection pressure checked. I hope that you're able to find the problem.
By the way does the vibration occur only in park and nuetral? Because, I can only feel the vibration in park and nuetral in my car.
Good Luck.
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  #12  
Old 10-17-2002, 08:34 PM
John_Schwarz
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My vibrates noticeably in Drive/Reverse. Park and Nuetral is very sublte, but you can still feel the peaks.
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  #13  
Old 10-19-2002, 09:34 AM
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I've owned my 400E (same M119 engine as yours) since it had 25 k miles. It has always had a less-than-smooth idle. I've had it back to the dealer under warranty and was told "All the V-8's do that." Not sure I believe it, mind you, but whatever it is, it is persistant and not progressive. I now have 119 k miles. It got a bit better after replacing motor mounts but there is still a subtle vibration at idle, in gear, esp. in warm weather. I notice it more after I've been stopped (say at a red light) for 10 seconds or so. Personally, in my case it's minor enough I've learned to live with it since the engine performs so well otherwise.
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'93 400E
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  #14  
Old 10-19-2002, 07:23 PM
John_Schwarz
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Hi 400E -

I could live with the vibration but... It didn't start until about a year ago. If is the vibration was constant and uniform, I'd consider it normal. But, it varies, has cycles, has highs & lows and similar to what you said, it starts a couple moments after stopping at a red light. I've contributed that part to the idle going from 600 to 700 RPMs will coming to a stop, and once the car is completely stopped the idle settles to 500 RPMs. Sometimes, giving the car just alittle more gas (while in gear and the brake is applied) and nudging the idle to 525/550 RPMs eliminates the vibration. This doesn't always work - but 60% or more - it works. I don't think this is the problem, it just hides it. At 525/550 RPMs there is too much resistance and you can hear it in the engine, etc.

The vibration is minor in the steering wheel, but it also causes noise in the cabin similar to back pressure in the exhaust - that probably gets to me the most. The car is due for its inspection, maybe the emissions test will shed some light on the culprit. The exhaust has the rotten-egg smell from time to time (e.g. the catalytic converter), but the shop said that occurs when the car burns rich. Techron is added every to 2k to 3k miles, so that's probably the cause. However, after 8 years and 96k miles, alittle exhaust work would not surprise me. Also, just about every sensor could be at fault.

Overall, I think it is a combination of factors - some mounts or bushing intended to absorb vibration need replacing, rehanging the exhaust is a good idea and finally the injectors probably need more than just a cleaning.

One final comment, this started after moving to Seattle from Dallas, TX. My first thought was the gas. It always gets premium from Chevron - however it 93 octane in Dallas, but only 92 Octane in Seattle. I've tried water removers in the gas, octane boosters, etc., No difference. So, I don't think it's the gas, but it's still an interesting coincidence.
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  #15  
Old 10-19-2002, 09:57 PM
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John,
I'll be interested to hear what you find. You are taking a very methodical approach so you will very likely figure it out soon.

I have read recently on the Ritter/Easley list that some aftermarket motor mounts are pretty lame. Even the factory ones don't last as long on our vehicles due to the V-8 (though sounds like yours check out OK). Did you know that the corrugated plastic ducts under your front bumper (if it's like mine) are there to route air to the motor mounts to keep them from frying from the higher underhood temps of the 400/500E?

Do you get your engine to do some heavy breathing (aka Italian tune-up) regularly? I started doing this about every week and it helps at least a little. The first time I did it, the engine started missing at about 5000 RPM. I persisted, and that's a thing of the past. (Stu Ritter had said that that would happen-- you just need to not lose your nerve and keep pedal to metal ...)

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