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Engine vibration absorber

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5 replies [Last post]
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Wallace Wheeler's picture
Dallas, TX
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Joined: October 5th, 2007

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271

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1968 280SE Coupe

My '68 111 280 SE engine shakes between 800 to 1100 RPM in park or neutral at idle and is most noticable when warm. When in drive, the shake is more subdued. I have the idle speed set just at 750 in park and 850 in drive. If I adjust the speed below 800 RPM, the engine smooths out with just a little twitch but is now too low and could stall. If I adjust it higher than 1100 RPM, it runs very smooth but is hard on the transmission when I shift into gear.

I have gone through just about everything I know to do as far as tuning and the mixture seems to adjusted correctly when I do the split linkage test. The spark plugs also look good.

My current thinking is now that the problem is with the engine suspension. I have examined both engine mounts and nothing looks seperated and the rubber is resilient. The rubber is bonded to the engine bracket screw and to the sides on the metal plate. The is an arc in the middle of the rubber that is not bonded and that is where all the engine movement takes place. It almost looks like a rubber leaf spring. Does this sound correct?

If it does act like a spring, then you should need to dampen it. I examined the vibration absorber on the front right of my engine and it appears to be original. With engine running and shaking at 850, the absorber DOES NOT MOVE AT ALL. I would have thought with the engine shaking that much, it should move some. Could this be the source of my problems.

I have never seen anything written about this absorber and wonder what is supposed to do. Thank you for your input and sorry for the long post!

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wbain's picture
Haymarket, VA
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Joined: December 1st, 2003

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891

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1965 220SEb
Re: Engine vibration absorber

Unbolt the engine shock and try to move it in and out. Replace it if seized. Next. check the crank damper.

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1965 220S, 1999 Volvo V70, 2002 FORD Crown Vic, 1972 350SL Euro 4 speed.

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Wallace Wheeler's picture
Dallas, TX
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Joined: October 5th, 2007

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271

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1968 280SE Coupe
Re: Engine vibration absorber

Thanks for the reply Warren.

I never would have thought shocks would seize, instead just loose their dampening ability. I will take it off and examine it. Seems like it should move some when the engine is running.

What should I look for on the engine damper? I know there is a rubber component but not sure where it is.

Does it sound like to you that this could be an engine suspension problem?

Thanks again.

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Tony H's picture
Rough and Ready, CA
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105

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1971 280SE Coupe
Re: Engine vibration absorber

If your engine and transmission mounts are old or if you don't know how old they are I would replace them(Along with your subframe mounts). Both my engine shocks were original and they were pretty much empty, dry shells. They are NLA but I found some on Ebay.

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Tony H

1971 3.5 coupe

Manual trans 3.27 axle

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Wallace Wheeler's picture
Dallas, TX
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Joined: October 5th, 2007

Posts:
271

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1968 280SE Coupe
Re: Engine vibration absorber

Thanks Tony,

Did you find any improvement when you replaced the engine shocks?

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bwostosh's picture
Spring Valley, CA
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Joined: August 18th, 1998

Posts:
126

Vehicles
1971 280SE
Re: Engine vibration absorber

Motor mounts,
when in doubt throw them out, they are cheap.
they can collapse,
Check fan positioning compare to fan shroud, should be concentric.

Also I have had an injector revelation recently.
Pull them out and test / clean / replace is necessary.
only at the last of a compression test, valve adjustment, and tune-up.

I have purchased two new sets recently,
it make a difference.

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