What to expect after valve adjustment 83 300D - PeachParts Mercedes-Benz Forum

ah-kay · #1 12-23-2009, 09:17 PM

Managed to get round to do the valve adjustment after don't know how many miles. I did 30K on the car since I bought it and do not know when was the PO last did the adjustment. Before the adjustment, the engine was running well at start up. When the engine is at temp, it shakes at idle, you can feel it inside the car at stop lights. Shaking gone at high rev.

All the valves were out of spec. I adjusted them as per spec, I followed a Haynes manual to do the adjustment. Removed the clutch fan and turned the engine clockwise at the crank shaft. I think I did everything right as I followed the manual to the letter.

This is what I experienced after the adjustment.

1) The car started with 1 or 2 spins, same as before. It idles a bit rough in the first few sec ( may be 5 ) and then it runs smoothly.
2) I cannot recall it ran rough before the adjustment.
3) The engine still shakes a little when at temp idling. May be it is a little less than before.
4) Car has 330K and no pop test has been done to injectors. May be they are the original injectors.
5) What shall I expect? How can I get rid of the shaking? Engine mount, shocks?

Any info is appreciated.

#2 12-23-2009, 09:23 PM

Well, the injectors could certainly make it run rough. I recently replaced mine and it did make a noticeable difference. You can also try adjusting the rack damper on the injection pump. Motor mounts will help if they are worn out. What is your idle speed?

Diesel911 · #3 12-23-2009, 11:32 PM

In order of what did the most good in taking out the Engine shake after the Engine was up to temp on my 84 300D.
Rebuilding the Injectors
Valve Adjustment
New Engine and Transmission Mounts
Fixed a small Fuel Hose inlet air leak (replaced hoses) that showed up only when the Engine was hot (It already had the New Style Hand Primer).
And, when all of the above was done the New Gold Colored Rack Damper Pin was able to remove some more shake.

I did not get around to Drip Timing until 1 year later and it did not have any effect on the Idle shake. I have about 2.5 degrees of Timing Chain/timing Gear Wear by alighning the Camshaft Timing marks and viewing Crankshaft Damper Degree marks.

ah-kay · #4 12-24-2009, 03:50 AM

Quote:

Originally Posted by Craig

Well, the injectors could certainly make it run rough. I recently replaced mine and it did make a noticeable difference. You can also try adjusting the rack damper on the injection pump. Motor mounts will help if they are worn out. What is your idle speed?

The idle speed is about 700-800rpm. I think it is about right. What is the "rack damper on the injection pump"? How can I adjust it?

The car seems to be running well as it was a well maintained one owner car. The idle shaking is noticable and I would like to fix it if is reasonably easy. But I can put up with it for a while.

johnathan1 · #5 12-24-2009, 04:17 AM

So worn injectors is usually the cause for idle shake?? Were not talking about vibration, but side-to-side shaking at stop lights. Another question...for us 240D owners with no tach, how can we determine idle speed/RPM?

#6 12-24-2009, 05:39 AM

Quote:

Originally Posted by ah-kay

The idle speed is about 700-800rpm. I think it is about right. What is the "rack damper on the injection pump"? How can I adjust it?

The car seems to be running well as it was a well maintained one owner car. The idle shaking is noticable and I would like to fix it if is reasonably easy. But I can put up with it for a while.

Here is a link for the rack damper:

http://articles.mbz.org/engine/diesel/rackbolt/

Your idle speed is good. A bad injector can cause one cylinder to miss, resulting in a pretty good shake.

meltedpanda · #7 12-24-2009, 09:26 AM

OK a little reality check, 330,000 miles is a lot of miles, granted it is a diesel. but rubber mounts must be inspected, as well as all the frame members for wear . Make sure fuel lines are not taking in air . Injectors are the first thing to replace, particullary if you think they are original. They may be a bear to get out if they are. Rack damper - needs the newer version bolt. Injection pump timing - a lot of things can make this engine vibrate. That said , some vibration is normal. I have noticed my 300SD now vibrates a bit more than she did in her prime, but suspect engine mounts, engine shock damper, and injection pump timing, but since it is only at idle and she is approaching 200K, I kinda equate it to graceful ageing

Kinda like her owner.

toomany MBZ · #8 12-24-2009, 10:54 AM

Quote:

Originally Posted by Craig

Here is a link for the rack damper:

http://articles.mbz.org/engine/diesel/rackbolt/

Your idle speed is good. A bad injector can cause one cylinder to miss, resulting in a pretty good shake.

I'll add there is an "O" ring also to be reused.

Yak · #9 12-24-2009, 11:39 AM

Quote:

Originally Posted by ah-kay

The idle shaking is noticable and I would like to fix it if is reasonably easy. But I can put up with it for a while.

I'm partway through my first tank of B100 and the warm idle/shaking on mine is reduced. I plan on having the nozzles cleaned and balanced in the near future, so I'm not suggesting this as a permanent fix for the side-to-side rocking at the stop light. Maybe try a blend to see if that affects your car.

I think this might be an "all the above" with basic tune-up stuff for getting a clean smooth burn - clean fuel, clean air filter, adjust valves, air-tight lines, clean injectors, good motor mounts and shocks, etc; incremental rather than drastic improvements.

okyoureabeast · #10 12-24-2009, 11:50 AM

I'll be honest I had the WORST shaking when I got my car out of storage.

It was bad enough for me to notice. However, after about 400-500 miles of driving the shaking disappeared.

My motor mounts are in remarkable condition for the mileage of the car. I'm guessing they were replaced before my stepdad came upon the car some 250,000 miles ago. Either way I want to replace them eventually.

Diesel911 · #11 12-24-2009, 01:16 PM

Quote:

Originally Posted by ah-kay

The idle speed is about 700-800rpm. I think it is about right. What is the "rack damper on the injection pump"? How can I adjust it?

The car seems to be running well as it was a well maintained one owner car. The idle shaking is noticable and I would like to fix it if is reasonably easy. But I can put up with it for a while.

No Turbocharger = No Rack Damper.
Not a good pic but the Yellow Arrow points at the Rack Damper.

Also the Rack Damper does not have enough effect to cure some majoir shaking caused by something else.
I believe it was made to take out the extra shake on a new Engine; not to compensate for worn Injectors, tight Valve Adjustments or unevern compression and so on.

Diesel911 · #12 12-24-2009, 01:25 PM

Quote:

Originally Posted by johnathan1

So worn injectors is usually the cause for idle shake?? Were not talking about vibration, but side-to-side shaking at stop lights. Another question...for us 240D owners with no tach, how can we determine idle speed/RPM?

It was for me but I would not assume that since it is expensive to have the Injectors Rebuilt. I rebuilt my own Injectors so there expense was at a minimum for me. (I have never tried that Diese Purge.)

Do the other things like Vavle Adjustment and the less expensive stuff first.

I have a Thread on the Photo Tachometer I bought. You stick a piece of Reflective Tape on something that rotates at the same speed as the Engine; in my case the Crakshaft Damper of the Volvo and you point and press a button and a digital readout tells you the RPM.

Harbor Freight and ebay sell them but unfortunately the price has gone up on them since I bought mine.

ah-kay · #13 12-24-2009, 01:26 PM

Thanks for the advices. I will tinker with it slowly. The car run smooth and does not vibrate. It just shake a bit from side to side and is noticeable when idling at stop light. Apart from that it has been a excellent car for 330K.