Diesel Shaker

[TCCBass]

My 1984 300D-T has the smoothest idle of any 300 I've owned (this is my 3rd). Except-after driving at highway speeds and coming to a stop, the entire car rocks like an old truck. I have changed all the filters and fuel bleed lines. The car has new engine and trannie mounts, and starts perfectly. The car does seem to smoke quite a bit. 202K miles, and major oil seals have been replaced. The car uses no oil at all (.5 quart in 3K miles). Noticed fuel smell coming from engine, tightened lines. On the highway the car gets up to the 100degree mark, running cooler in town. The shaking is only after the car idles after higher extended RPM's. MPG: average 24. EGR vacuum line is plugged (was told to do so by mechanic), have run 3 tanks of Redline Diesel Catalyst through. Good power, but tired of the "shakes" and smoke.

[poptest]

Check your in-tank fuel strainer, then your pre-filter. First line of defense against dirt is the in-tank strainer.

Hope this helps.

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Jake

[TCCBass]

I thought the in tank screen was clogged on my last 300D, but when I took it out it was spotless. That car was doing the same thing, just at random times. Is there a way to take the fuel screen out without removing the fuel tank? My neighbors didn't like the neighborhood smelling like diesel for a week.

[stevebfl]

The oscillation of the fuel rack at idle was a problem with those years Turbodiesels. The problem is greatly accentuated by too high of an idle speed. It seems that motor often has a higher idle after a hot run also.

The first check I would do is to pull over to a safe parking place and do a little diagnostic. With the engine idling (poorly) push lightly on the "STOP" linkage. This will drive the idle down. Drive it slowly down and see if the engine smooths out. It probably will.

If thats the case a proper idle set up is in order by someone who can read the actual rpm. There are a number of different types, the one we use is made by Snap-On. It clamps to the number one injector line and the battery. It makes a signal that a standaard timing light uses. With a light that gives rpm and light indication you are all set.

The first fix that MB had to the 116 body car was to add a rack dampener to the rear plate of the pump. A proper adjustment will include this adjustment also.

The next step is a compression test and injector bench test if the results are good. Next pump element brass seals and then send the pump out.

BTW if you use this timing method you have to use different specs than the drip or high pressure methods.


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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Steve Brotherton,

It's nice to see another ACE on mercedesshop. Thanks for the good info.

Welcome,

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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
Over 800,000 miles in
Mercedes automobiles

TCCBass,

I haven't looked lately, but it seems like the fuel tank sender etc is accessible just below the first aid kit. I'm not sure, but I think it would be worth taking a look.

Good Luck,

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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
Over 800,000 miles in
Mercedes automobiles

[DieselGuy]

TCCBass,

I have a 1984 300SD that did that for several years. After a long run with a hot engine, the entire car shakes like crazy. Recently through MB archives on the internet, I dicovered that the fuel rack damper screw was the most likely cause. This damper screw is on the bottom of the back plate of the fuel pump. I've read that it is very common for the older style rack damper screws to be fatigued. A new screw only cost me $8 here in LA, Ca. I removed the old screw, put in the new one(not tight). I ran the car until the shakes came and slowly turned the damper screw in until the shaking stopped. Then tighten down the lock nut. At $8 it seems like a easy thing to try. Now matter how hot or hard I run my car, no shakes, no starting or idling problems(270,000miles)... Simply a great fix. Good luck with your diagnosis!

Nolan

REPLACE THE IDLE RACK DAMPER !
THE DAMPER IS THAT WEIRD BOLT ON THE REAR OF THE INJECTOR PUMP NEAR THE BOTTOM .TO ADJ. TURN DAMPER IN UNTIL YOU GET A SMOOTH IDLE BUT DON'T GO TOO FAR OR ENGINE WILL STALL WHEN COLD!!! M.F.


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M.F.

[TCCBass]

Thanks ALL for the bolt advise!!! I put the updated version in and am still working on final adjustments, but it is worlds better. Now, if I can just get the steering box adjusted. The lock nut comes loose, but the Allen bolt will NOT budge-even with a hammer. Any thoughts appreciated.