You start your post by saying the vibe appears at idle between 16-1700 rpms. Idle implys a no load condition. Then you confuse the issue by saying that is where the wife "always" drives. How can someone "always" drive a Benz diesel at that rpm. My 300 Turbo is barely moving at 1600. Then in your last post it is under load, (uphill), no load, (downhill). How much hill will that car pull at 1600 rpm. I think you better really look at that harmonic balancer. That thing is really capable of wrecking your engine, not the IP.

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Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

Yep, barely moving, that's right. What I'm trying to say is, that the vibe occurs always at that same rpm range, no matter if under load or not. The only thing that has any influence on the vibe occuring or not is the rpm, nothing else.

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'99 S420, 155k
'91 VW Vanagon GL, 150k
'85 VW Vanagon GL, 120k
'82 VW Westy, aircooled, 165k

I talked to my mechanic about the harmonic balancer. He said it is a possibility though he hasn't seen many going bad yet. He wants to test that by taking it out and run the engine for a couple of seconds without the balancer. I agree with him that you would see it right away if the balancer is bad or not, but the thought scares me running a halfway disassembled engine...
Is there a better way?

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'99 S420, 155k
'91 VW Vanagon GL, 150k
'85 VW Vanagon GL, 120k
'82 VW Westy, aircooled, 165k

If the engine making a droning noise and less of a vibration...I would not be so suspect of the IP.

Thanks for the better description of the sound...helps rule out some things

I've never had a benz harmonic balancer off but isn't a front main seal surface part of the harmonic balancer as it is on some engines?

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

I don't know if the hb could be well examined without removing it. I would suspect that removing it would really be the best way. If upon inspection the hb checks out to be A-OK, I would re install it without running it, unless I had a good assurance from someone in the know that it could be done. Then I would very carefully re-install, reading some of those very recent posts on how to properly re-install, correct placement of the spring washers, making oh so sure that those keepers are in there correct and not to use impact wrench. But it is a difficult job no doubt, and do it only as a last resort. Maybe like Tom mentioned, you don't even have a problem, or my suggestion, drive it a little faster. This just came to mind. Do you think it could have a "pick and pull' balancer installed that does not match the engine very well?

__________________
Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

Everything is possible with this car. I just recently bought it and found strange things like wrong foglights, not even connected, no airfilter, no spare wheel, missing swaybar, etc... So I guess I'll have the shop check it out before all that money I put into that car already is wasted in a wrecked engine.

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'99 S420, 155k
'91 VW Vanagon GL, 150k
'85 VW Vanagon GL, 120k
'82 VW Westy, aircooled, 165k

Thanks to Brian Carlton we probably found the problem: bad transmission mount. I guess I looked in a completely wrong place in the beginning.
I checked it today, after digging through a quarter inch of oil gunk I finally touched rubber, well, let's say what was left of rubber. This piece of rubber is so deteriorated, I could peel pieces out with my fingernail. It is not even rubber anymore, it's just oilsoaked spongy mass.
Which tranny mount should I order, the one with the oval or the one without? What's the difference?

__________________
'99 S420, 155k
'91 VW Vanagon GL, 150k
'85 VW Vanagon GL, 120k
'82 VW Westy, aircooled, 165k

I had a good look at this vehicle on Sunday. And, I'm pleased to hear the "good" news, Andy. With the mount in such poor condition, I feel confident that we are moving forward toward a final solution.

I'm quite convinced that it has nothing to do with the engine itself. That engine runs extremely smooth once it's warm. All of the "vibration" is caused by harmonics within the body when the normal vibration of the five cylinder is not isolated.

The symptom is not "shaking" per se. It's more like a "drone" between 1600 and 1700 rpm when something on the body is excited into a resonance.

The lack of a hood pad is probably exaggerating the problem.

... now fix mine!

bnc

...........you go work on you springs and suspension parts.........

I just replaced the tranny mount: no change. Then I removed the bracket that connects the down pipe to the transmission: no change. I mean NO difference at all. Still f*ckin' vibrating. Now what???

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'99 S420, 155k
'91 VW Vanagon GL, 150k
'85 VW Vanagon GL, 120k
'82 VW Westy, aircooled, 165k

Andy, I'm leaning in the direction of BHD in post #11. This must be investigated. Make an inquiry to the shop as to what they purchased for those mounts. If the engine is properly isolated from the body, the sound that you hear cannot be transmitted through to the body.

Andy, Brian, that's really bad news the new transmission mount did not fix the vib. I have exactly the same vib on my 83 300D, though it occurs between 1400 to 1700, no matter if the car is standing still or moving, in gear or neutral.

What's next? Any other ideas? How about listening with a stethescope under the vehicle at various spots while someone is throttling the idle to narrow down the origin of the vib?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

funola, that's what I'm doing right now, not with a stethoscope, though, just feeling it and I believe the vibration is most noticable on the transmission itself. But since there is nothing moving inside the tranny while in "P" or "N" (?) it must be transferred from the engine. And the vibe is more noticable on the tranny than around the front engine mounts and that's why I believe there is an imbalance in the crankshaft which brings us back to the harmonic balancer. I think we ruled out the IP since the car is running fine otherwise.
Brian, I felt the engine carriers on top of the mounts and also the body underneath them, the vibes are noticable on the engine, but there is no vibration transferred to the body at this point. Changing bad mounts with possibly but unlikely wrong mounts should have made some kind of a difference in my opinion, but it did not.
Are there ways to narrow the cause or rule out other causes?

__________________
'99 S420, 155k
'91 VW Vanagon GL, 150k
'85 VW Vanagon GL, 120k
'82 VW Westy, aircooled, 165k