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  #16  
Old 02-27-2018, 11:16 PM
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Same car, same issue - resurrecting this thread. Did any of you resolve this?

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  #17  
Old 02-28-2018, 12:07 AM
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I’d bet on throttle linkage issues first and I’d be looking at the throttle damper as well.

There are plenty of other things that could cause a parade clunk though.
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  #18  
Old 02-28-2018, 12:25 AM
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Independently, I'm preparing a bit of a drive train refurb (flex discs, center bearing, front/rear shocks, transmission mount...)

Throttle damper sounds interesting... where would I access this?

EDIT* found a diagram... this actually has a bit of play in the ball joint. I remember rattling this around during a valve adjustment. Is there a resistance one should feel when it's in

Last edited by Shern; 02-28-2018 at 01:21 AM.
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  #19  
Old 02-28-2018, 01:16 AM
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Sorry, I still haven't gotten a chance to work on the car. In my case everything is loose from the pedal pivot point through ball joints to the leaver mounted on the valve cover. It's a very good place to start.
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  #20  
Old 02-28-2018, 07:28 AM
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I'd not worry about the rumble when idling in first gear. Its probably just gear noise. They're not really designed with that in mind.
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  #21  
Old 02-28-2018, 07:34 AM
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I often think so too. With an automatic engine pulses are dampened by the torque converter. The throttle input also. Seems like I bought the wrong one gearbox wise
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  #22  
Old 02-28-2018, 02:51 PM
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I checked the bushing in the back of the engine bay and that’s totally intact.
To anyone with a working dampener, what sort of motion should it have?
When I pull the throttle on the engine (using the emergency shut off), as soon as I let go, I rockets right back down. Should this be a smoother movement?
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  #23  
Old 02-28-2018, 06:21 PM
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Quote:
Originally Posted by Shern View Post
I checked the bushing in the back of the engine bay and that’s totally intact.
To anyone with a working dampener, what sort of motion should it have?
When I pull the throttle on the engine (using the emergency shut off), as soon as I let go, I rockets right back down. Should this be a smoother movement?
My mechanic told me it should be smooth, mine is wearing out.
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  #24  
Old 02-28-2018, 06:49 PM
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Ok... so, you are dropping the clutch?

Smooth is achieved by smoothly releasing the clutch. Smoothly accelerating is key as well...
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  #25  
Old 02-28-2018, 08:05 PM
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Quote:
Originally Posted by vstech View Post
Ok... so, you are dropping the clutch?

Smooth is achieved by smoothly releasing the clutch. Smoothly accelerating is key as well...
I believe this is true, but only to a certain extent. I own two Euro import W123 300d with identical milage as each other. (227k) The '82 wasn't maintained that well prior to my ownership, and the '84 is in immaculate condition and has always been serviced by Mercedes. That being said, they drive completely different from each other. The 82' has the exact symptoms as described in the first post of this thread, and no matter how smoothly the throttle is applied or let go of there is always a slight jerk. If you wanted to, you could abruptly apply the throttle and let go of it repeatedly to make the car violently "rodeo" This is not the case what so ever with the '84, and they are the exact same milage and model. I believe this is directly related to maintenance which then comes down to driveline slack, the '82 has quite a bit compared to the '84. This is probably the case for the original poster.
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  #26  
Old 02-28-2018, 08:37 PM
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Quote:
Originally Posted by vstech View Post
Ok... so, you are dropping the clutch?

Smooth is achieved by smoothly releasing the clutch. Smoothly accelerating is key as well...
Hmm, guess I wasn’t clear. Clutch doesn’t really come into this...
as OP said, unless one feathers not only the clutch but the gas pedal, there’s jerking. In my post, I was referring specifically the operation of the throttle linkage (when the car is not in gear) with me under the hood and watching the damper provide little to no cushioning. If I’m driving along in gear and I press on the pedal and release, it is not a smooth operation.

I checked the main bushing by the firewall and it appears to be intact -at least not missing any parts. It seems like this is a damper issue, but without having seen or experienced any other dampers, I can’t be certain.
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  #27  
Old 02-28-2018, 09:03 PM
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Originally Posted by koooop View Post
My mechanic told me it should be smooth, mine is wearing out.
Have you found a replacement or a part number?
Not finding much on pelican or eBay. Did find something on UK ebay but surely there’s something local.
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  #28  
Old 03-04-2018, 09:29 PM
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I installed a new throttle damper. I like it, but it doesn't solve the issue.

I've followed the issue from the pedal to the valve cover and found some (possibly) odd behavior. If I pull the throttle on the valve cover, the engine revs accordingly. When I release it suddenly, the engine sputters a bit before it resumes its idle.

I imagine this happening while the driveline is engaged would create a bit of a jerk?

Incidentally, I'm fairly certain I have an air leak somewhere... On the first start of the day, I'm getting a rough choking start and a little knocking for about a minute before it smooths out. Starts instantly, but sputters after about 10 seconds and knocks lightly while I imagine the air is clearing. Could these issues be connected?
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  #29  
Old 03-06-2018, 03:37 PM
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Good thing to check. Air as a percentage of fuel could be higher at low revolutions. Or the issues it produces more apparent then.


Also especially since the car has the 616 engine the fuel system should be checked out well. Not expensive to do either other than the injectors being checked for condition usually.


The car is thirty five years old and in all too many cases it has been years since anything much was checked. If anything on a lot of them. The last owner may not have even done a valve clearance check. They should at least be checked every fifteen thousand miles. This also could be a portion or contributor to your current issues.


These engines do not require a lot of maintenance. Yet none done over a very long time will have consequences. You may as well check the timing chain for excessive stretching as well. Not doing this can cost you the engine. Also the condition of the oil cooler hoses. As the engine can be easily destroyed if they fail.


Generally paid for service is not a practical reality with these old cars and many other brands today. So the owner and perhaps a friend do it or it does not usually get done.


At least with the assistance of this very useful site. You can do a lot yourself. To me just having the proper fuel pressure available to the injection pump is important on the 616 engines. Air free of course as well.


I freely admit on more complex cars. I have engaged in a general tune up of all the engine systems. Basically checking them and repairing any that were found less than normal.


Either I found the problem in many cases or the problem was gone along the way. Or I found a good indicator of what it may be. At least I then knew what it was not. On a neglected very old car you can have a lot of accumulated minor problems.
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  #30  
Old 03-06-2018, 10:21 PM
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Hey Barry, I appreciate the response. Regarding the fuel system, I’ve recently rebuilt my injectors and valves were adjusted a couple of weeks ago. I read your 35 page manifesto on the injector pump spring length… there are two areas that could be of interest, at least intuitively speaking: drivetrain, fuel pressure.

Re driveline... if there’s a “slack” of some sort between clutch(Bear with me because I don’t entirely understand how power makes it to the wheels) and rear wheels, I can imagine a jolt happening on pedal press and pedal release as the drive line either catches up or falls behind.

Re fuel system... I don’t appear to have any issues with fuel pressure -at least in my experience, which granted it’s far from sophisticated. I can easily cruise along on the highway at 75 mph and engine fires right up (a little rocky initially). There’s something about a surge of fuel the engine can’t quite seem to handle. When the surge disappears, the idle dips below normal for a beat, then returns. When the surge is requested (through my pedal) there’s a beat and then a jolt. I’m afraid I don’t know enough about the system to ask an intelligent question… hopefully something can be gleaned from this description .

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