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Old 08-28-2005, 06:57 AM
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Join Date: Sep 2004
Location: Kittrell, NC
Posts: 681
Hot idle shaking in 300sd

Ok. I have tried everything to solve this problem.

I recently had the motor mounts replaced. Afterwards, the engine vibrations got worse, not better.

I have tried numerous fuel additives including recently putting in a whole bottle of RED Line. In the past I have used Power Service and tried Lucas which after using the lucas I had to change my filters cause they turned black from the crap it got out of the tank. I have purged the injectors with Lubro molly three times now since buying the car at 245,000mi.

My fuel filters are brand new. The fuel from the tank is very clean.

I can start the car and it idles perfectly when engine is cold. But when it is fully hot at normal operating temp, idle shake is noticeable. It is not as bad on mornings when the air temp outside is noticeably cool.

Maybe it is time for a valve adjustment. I am less than 10,000 miles since the last one. But the way cool outside air makes a difference makes me think an intake valve is tight.

I am leaning towards pulling the injectors and having them tested. I do have a local place that can test them called Southereastern diesel.

What do you folks think? I guess a valve adjustment would rule out that issue. I replaced the rack dampener bolt with a new Bosch right after buying the car at 245,000mi. I have never replaced the engine shocks. I do have the new rubber pieces for the ends of them. They look bad. I read some folks say these really make a difference and others don't. Adjusting rack dampener and repalce these before pulling injectors??

1982 300sd with 263,000miles.
1982 300SD Light Blue
2002 Honda Accord SE
1974 Toro Wheel Horse Tractor
2000 Toyota Tundra Pickup

Last edited by willrev; 08-28-2005 at 07:07 AM. Reason: add
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Old 08-28-2005, 08:58 AM
t walgamuth's Avatar
Join Date: Apr 2005
Location: Lafayette Indiana
Posts: 33,616
engine shocks

may help.

i would try cracking the injectors to see if it is isolated to one cyl. if it is then i would suspect low compression. if it is not isolatable to one cyl then i would say it sounds as if it is starving for fuel. they run rough for a little while before running completely out of fuel. (ask how i know).

doesnt seem like vavles are likely unless a mistake was made when adjusting them.

tom w
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual. It still needs upholstery redone...I also have a 427 Cobra replica with an aluminum chassis.
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Old 08-28-2005, 09:01 AM
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Join Date: Feb 2002
Location: Virginia
Posts: 550
Engine shaking and OM 617s go together like peanut butter and jelly. I'm a fan of the rack damper pin theory, especially if it hasn't been adjusted previously. Just adjust it clockwise until you no longer have the shakes when the engine warms up. Be aware that if the pin is too tight, it can hamper your cold starts. Between that and a valve adjust you may lick this without having to mess with the injectors.

82 300 SD
77 450 SL (gone)
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Old 08-28-2005, 11:15 AM
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Join Date: Sep 2004
Posts: 8,591
I would focus on the governor idle pin. For best results, adjust it with the transmission in Drive and the engine hot. The fact that the shake occurs only when the engine is warm would tend to point to the idle pin.
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Old 08-28-2005, 11:18 AM
pawoSD's Avatar
Join Date: Oct 2004
Location: Grand Rapids, MI
Posts: 14,981
I had the same problem, I bought a new rack damper pin, and it took away some of the shake, then I went back to regular premium diesel instead of B20 biodiesel, it smoothed right out, no more shaking at all. This means the new pin did work, as it used to shake on either type of fuel, now it only does on B20. I'll also add that it gains power on regular diesel, and sounds quieter....I have no idea why this is. This is very high grade diesel from a local station, they add fuel lubricants and injection additives and so on to it......

On top of it I am actually late for a valve adjustment....I'm at almost 17k since the last one was done....I'll be having one done in September or early october...
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 75k - mine - (OC-80,500)
'17 Metris(VITO!) - 6k - wifes (OC-10k)
'01 E320 Wagon - 157k - mine (OC-160,000)
'89 420SEL 166k - mine (OC-167,000)
'01 E320 - 167k - dad's (OC-171,500)
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'01 SL500 - 48k - dad's (OC-52,000)
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