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1982 300SD idle vibration
I've got a perplexing situation with the 82 SD. The engine has roughly 160,000 miles on it, as far as I know the original injectors have never been serviced.
The car has a LONG history (I have partial service records going back to the 80s) of having parts changed to cure this problem. I'll list just the "interesting" items. 1983 24,000 miles: "rough idle" listed on service chart, no parts changed 1992 87,000 miles: air filter mounts had to be changed; implies vibration 1992 88,000 miles: one valve had to be replaced. Isn't this a bit unusual for a car that was, at the time, so young? 1998 96,000 miles: Replaced motor mounts AND shocks A few months ago, 155,000 miles: replaced air cleaner mounts Last saturday: replaced motor mounts again. And it still persists. The thing is, it does not do it consistently. Some days, it idles 100% smoothly and you sit there and don't feel a thing. Other days, at idle and at idle only, the engine SOUNDS fine, but it gives you a back massage from the seat bouncing up and down. Passengers are literally visibly going up and down in their seats a fraction of an inch. The one "trend", if there is such, is that TYPICALLY, it is more likely to exhibit this behavior after a hot day, or after a long, hot interstate drive. If you putter to the grocery store on a cool day at 35, it typically idles smoothly. If you go 100 miles at 70 and then roll to a stop light, it's usually bouncing you around. But these are not "absolute" behaviors. I am starting to wonder if this is just a typical 5-cylinder behavior. I have never owned or even driven one before we got this one. All I know is that you can't feel my worn out 4 cylinder or my nicer 6 cylinder in the seats, but you do feel this one. The air filter vibrates so hard under the hood when you look at it at idle that you can't see the nut on top, just a blur as it moves back and forth. Once you put a LITTLE rpm into the thing, it smooths right out. But I don't think it's a slow idle problem; it appears to idle at 750 or 800 rpm which I think is where it should. I don't want to "temporary fix" it by elevating the idle speed, because I like hearing them idle normally. Just not used to feeling it. John, if I'm ever near Charlotte in the thing I may ask you to look just to compare it and see if your 5 cylinders are similar in behavior, but IDK when that will be so I'd rather just poll the forum as usual, first. I'm wondering if this is just something all 5 cylinder engines do; I would think it would be perpetually out of balance compared to even numbers. Since this car has had a history since 25K miles of having a rough idle, I'm wondering if I just got a bad build or something. Any thoughts? What else could it be since mounts didn't fix it like I thought they would? |
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very common.
search "wife's boobs shake" or "car shakes my wife's boobs" or similar here on the fourm... TONS of great "helpful" tips. mine does the same thing lately. perhaps time to adjust the valves again. the blurring air cleaner is likely a LOT of things loose. I had a customer's 85, and after tuneing and replacing seals and such. ZERO vibration on the air cleaner. and before it would hammer the valve cover. found it
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread "as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do! My drivers: 1987 190D 2.5Turbo 1987 190D 2.5Turbo 1987 190D 2.5-5SPEED!!! 1987 300TD 1987 300TD 1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere! |
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I used to have an '83 300D that never had engine shake, not even after the mounts collapsed down to the frame. It was plenty noisy then, but it didn't shake.
My '81 300TD does it intermittently, in spite of having good mounts. I'm thinking valve adjustment, then rack damper pin. I don't think it's inherent to 5-cylinder engines. I've been in Audis that were very smooth.
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1981 Mercedes 300TD, 1994 Honda Civic Del Sol http://mefi.us/images/fuelly/smallsig-us/67195.pnghttp://mefi.us/images/fuelly/smallsig-us/103885.png |
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I think your experience is pretty typical. I am the original owner of an '81 300SD. Sometimes I think there must be a "shake" and "don't shake" switch under the hood. It will shake miserably at a stop light and at the next light it will be smooth as silk. I had my indy idle it up some about fifteen years ago and that helped some. But still it shakes sometimes and does not at others.
Replacement of the rubber bumpers under the air cleaner is typical. Probably exacerbated by the amount of shake but I have replaced mine probably a dozen times since I bought it. But it's a great car and I would not trade it - in fact I did not trade it - yet. |
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'83 SD, 2x '85 SD You are entitled to your own opinions, you are not entitled to your own facts. |
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My '83 300SD never did any of that stuff. Mine was a dream for the 305K miles I owned it. |
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Most likely rack damper. See post #40 in the "boobs" thread.
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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar. 83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles 08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles 88 Jaguar XJS V12 94,xxx miles. Work in progress. |
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So... I'm not arguing with you, I'm asking you to clarify what you're thinking the relationship might be. |
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I'll take care of both the valve adjustment and the damper bolt ($65.00, ouch! May try half a dozen pull-a-part ones until I find one less worn than mine) and report back.
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#11
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The rack damper is adjustable. Yours probably doesn't need replacement, just adjustment.
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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar. 83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles 08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles 88 Jaguar XJS V12 94,xxx miles. Work in progress. |
#12
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Worn steering damper shock never gave my '83 300SD any vibration problems. Just steering wheel dampening absence.
Three things gave vibration problems - air filter assemby rubber mounts going bad, air filter assembly bracket shearing at the engine, and engine mounts. No other vibration issues from my 300SD. Maybe I was lucky in all the years/miles I drove it? Best single car out of all (5) I've owned in 37 years. Bar none. |
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SRJ, thanks for the clarification. Makes sense. |
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#15
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__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread "as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do! My drivers: 1987 190D 2.5Turbo 1987 190D 2.5Turbo 1987 190D 2.5-5SPEED!!! 1987 300TD 1987 300TD 1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere! |
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