Right,
So I have a drivable martini shaker of a car.
After stripping the motor mount bolt and having no love getting the SOB out, I brought the car to an indy, who had to pull the arm and cut the mount off. Total bill was just under $400, but that included installing all three of my motor mounts, and installing an engine shock (plus the shock its self) so not too bad of a bill. Thing is, while the mounts and shock were decidedly bad, the car shakes now more than ever. Any suggestions where else to look for the cause of shaking?
It levels off just below 1Krpm and is perfectly smooth and plenty drivable once at speed. I suspect I have a "soft" cylinder, but have yet to compression test it. It doesn't sound like it's missing (like it did when I had fouled injectors and a bad glow plug... talk about a miss and nailing).
I'd really like to drive the car (it has AC, my truck does not), but I'm afraid the shaking will rattle the engine to bits (never mind me).

Sooooo...
Any thoughts?

The bright side, I just got back from a vacation that included the purchase of some everclear, so I can make some wicked-dry martinis if nothing else...

-nB

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'83 300D Turbo
Current: ???K mi - 19.2mpg -> 17.4mpg -> 22.9mpg ---> ODO Died
bought at: 233.8K mi - 10MPG For $1.00
3.5 cylinders work: 320 320 100 340 280
Got insurance? FarmersReallySucks.Com

Havin' a similar problem on the SD, have replaced all rubber, braided, fuel lines under hood, have done purge, new filters, have cracked each injector, yes one by one! gets even worse. Still shakes harder than I do!

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83 SD

84 CD

Power balance test time? Millivolt method applied with thought to eliminate variables? Preceded with a valve clearance check, compression test and cam and injection pump timing check. You should be able to find whatever it is with this combination. You may not like what you find though. Before going down that road I would run the engine on a container of fuel to eliminate air as a cause.

I ditto Barry, check the valve clearance.

Doesn't every state sell Everclear, the magical elixor?

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2000 VW Jetta TDI with 213,000 miles and climbing
84 300D non turbo getting ready for wvo conversion

First, California has a max proof of 151, so no everclear
Second, good link to millivolt method?
Third, will do on the air check.
Fourth, indy did valves less than 3K miles ago.
Fifth, power balance check?
-nB

__________________
'83 300D Turbo
Current: ???K mi - 19.2mpg -> 17.4mpg -> 22.9mpg ---> ODO Died
bought at: 233.8K mi - 10MPG For $1.00
3.5 cylinders work: 320 320 100 340 280
Got insurance? FarmersReallySucks.Com

I know I won't like what I find, yet need to determine cause. See "have done purge". Did not shake during. What is power balance, millivolt? Everclear not available here either!

__________________
83 SD

84 CD

First you want to establish by compression check that compression is fairly consistant across the engine. This is also the early stages of a power balance check. If one cylinder is not carring its share of the load properly if at all the engine will shake pretty bad at lower rpm. The power balance or equal contribution of all the cylinders to allow smooth running is not there.
The refined version with the milli volts is used if most engine paremeters check out yet there is still a power imbalance and no indication of what may be causing it.
It"s used to find things like a poor injector or an injection pump out of normal operating profiles. Or just to absolutly identify the cylinder or cylinders causing the problem. Or prove nothing is wrong where you suspect there is.
The cylinder reads good compression yet does not burn as hot as other cylinders with about the same compression for example. Or burns much hotter. Of course again things like the engine overall timing must be reasonable and checked as they could also contribute to the problem or even be the problem. The miil volt thing is later again and determines the operating condition of each cylinder by reading the burn temperature in any cylinder compared to any other cylinder in the engine.
Primarily a comparison test somewhat like a compression check but for different dynamics. With your extreme low rpm shake if it is that bad you should find an indicator of cause pretty fast by testing. Or eliminate the engine as the source.
A kind of primer exists in the archives on the milli volt methods. It is far from complete but might stimulate your imagination. Always check on site to verify any variables you may have overlooked with that type of testing before you apply it. Again you have quite a few things to do before even thinking of going there. Some of the balls missing out of your prechambers or damaged prechambers could be another fault here as well. Just on the lower end of the totem pole right now.
You have completed the drop the cylinder test offline by loosening the line nut at each injector with no indication anything is amiss. Or was it too hard to tell with engine shaking so bad before you did the individual tests? If all cylinders dropped off all are firing to some extent. You had a valve adjustment 3k ago. Is there any chance the mechanic missed tightning down a jam nut and valve clearance has closed up on one cylinder?

I do not have a 5 cylinder, so I am inexperienced in trouble shooting them, however, most of the reasons for vibration are pretty straight forward. By the way, it is unclear if the problem is worst at idle or off idle. You only say it gets better at over 1,000 rpm.

There are obvious things, like:
1. Valve clearances being out of specification, and significantly different
2. Injectors being unevenly worn or damaged
3. Compression being uneven due to engine wear
4. The Indy screwed up the job.
5. The engine is idling slower than it used to.

There are also provisions cited in the archives here about a "rack dampner" screw that is supposed to preclude an injection pump rack resonance that will lead to an amplification of the vibration magnitude. Do a search. This bolt apparently wears over time and needs to either be adjusted (tightened) or replaced.

My instinct is the Indy screwed something up. If you change the mounts and shock and the vibration gets worse at idle there is a strong possiblility the work done to change the mounts changed the source of vibration, or the mounting system ability to absorb the vibration. One way to change the mount system response is to change the idle speed - lowering the idle speed will reduce the main vibration frequency, and if it is lowered enough, it may approach the mounting system natural frequency. If that is the case the mounts amplify rather than damp the vibrations.

Another issue might be that the mounts have been installed incorrectly and they are now stiffer than they were intended to be, which is the same thing that happens when the mounts wear out. The natural frequency increases and can approach the primary vibration mode frequency, resulting in another case where the mounts do the opposite of what was intended and the vibration amplitudes increase.

Generally, if you do work on the car and something gets "worse" the cause is most likely the work you just did. I would be inclined to check the idle speed, the rack dampner screw, and the condition of the mounts. Seems like there is something fishy with the changed parts, or perhaps some vacuum line or other idle speed control feature has been inadvertently disconnected. After I was sure these items are not the problem, I would check the valve clearances and have the injectors tested. The last thing I would do is a compression test. These are often difficult to have done, and you will likely have to do a wet and dry test, at temperature. Reading the results is often beyond the experience of many non-Diesel specific shops.

Good luck and I hope some of this helps. Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Adjust the Rack Damper Bolt...... !!!

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1984 Euro 300SDC, (4spd standard)
1986 Toyota Landcruiser Diesel HJ60 5spd X2

Gone but not forgotten (some sold, some stripped)
1983 300 SD, 1985 300 SD, 1983 240D, 1986 300 SDL, 1985 300 SDL, 1983 300 D, 1984 300 D, 1985 300SD, 1987 300 SDL, 1983 300 SD, 1985 300 TD Euro, 1983 380SEC, 1990 300 D, 1987 300D, 1982 300D, 1982 300D, 1994 E420, 1987 300 TD, 1987 300 D, 1984 300 D

Sorry I should have been more specific, in my last post, Pre 84 engines have a weak rack damper spring, there was a new spring design added for 84 and 85s This part can be ordered online from diesel giant, last time i looked i couldnt find it on this site..

The adjustment procedure is listed on this website, but essentially with the car warmed up and shaking, losten the lock bolt then screw in the smaller bolt slowly untill the shaking gets better, go really slowly, in and out a few times to get the sweet spot, if you go to far it will be harder to start.

If adjusting it in full doesnt help then you have a bad bolt, and should replace with the updated part.

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1984 Euro 300SDC, (4spd standard)
1986 Toyota Landcruiser Diesel HJ60 5spd X2

Gone but not forgotten (some sold, some stripped)
1983 300 SD, 1985 300 SD, 1983 240D, 1986 300 SDL, 1985 300 SDL, 1983 300 D, 1984 300 D, 1985 300SD, 1987 300 SDL, 1983 300 SD, 1985 300 TD Euro, 1983 380SEC, 1990 300 D, 1987 300D, 1982 300D, 1982 300D, 1994 E420, 1987 300 TD, 1987 300 D, 1984 300 D

Wasn't as bad this morning, but got worse as I drove to work and the engine heated up.

I'm fairly sure the valve adjustment was fine, as the indy that works on this car (and did for the PO for the last 12 years or so), does it because he likes the older diesels. I think a compression test is in my future. any comments on the harbor freight unit's quality? I'll buy it next time it's on sale.

-nB

__________________
'83 300D Turbo
Current: ???K mi - 19.2mpg -> 17.4mpg -> 22.9mpg ---> ODO Died
bought at: 233.8K mi - 10MPG For $1.00
3.5 cylinders work: 320 320 100 340 280
Got insurance? FarmersReallySucks.Com

Perhaps the car was recently "Traumatized"...? Did you scare the daylights out of it recently, by slamming on the brakes, or having a "Near-Miss" of some sort..?

Perhaps it is just scared to go beyond a certain speed now..

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[SIGPIC][/SIGPIC]

My 240D was shaking a lot at idle. I changed two of the injectors and now the car idles very well. Cracking the injectors did'nt tell me much, so I just replaced two of them and was fortunate enough to pick the faulty ones.

There is a Bosch authorized service center relatively near by. Can they test the injectors? Do they charge (what is fair)? I cleaned them up and my nailing went away pronto, so not sure if that's the issue. Reading up on the dampner, it looks like this is my issue, as I idle better when cold then when hot.

I should have been more clear in my initial problem description, the car has always been quite a shaker, just seems to be "coupling" better now that the mounts are fresh (one was failing[tranny], one had failed[passenger side]).

The car starts up just fine in the morning (a couple cranks, but no struggling to keep running like it did with bad GPs).
-nB

__________________
'83 300D Turbo
Current: ???K mi - 19.2mpg -> 17.4mpg -> 22.9mpg ---> ODO Died
bought at: 233.8K mi - 10MPG For $1.00
3.5 cylinders work: 320 320 100 340 280
Got insurance? FarmersReallySucks.Com

New heat shields on the way, when I opened each line at injector, there was a discernible worsening. Will do a compression test after they arrive. barry... may have to do that milli thing. I have 5 known good injectors, with new Bosch nozzles, that I pulled out of a car recently sent off to the great autobahn in the sky. Have adjusted RD, this is a different problem. networkboy, the service center can test injectors, I had five done for $60.00. That's how I know I have a set of good ones.

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83 SD

84 CD