Loud Tapping, Rough Idle, Had to Tow
 

Last week my 1985 300CD wouldn't start. I determined it was the Neutral Safety Switch. Ive been starting it with a coat hanger, jumping it at the terminal near the battery to get around until I get a new NSS.

I was also chasing an oil leak yesterday and drained some of the oil because I found it was over-filled. I did a diesel purge at this point also to make sure it was healthy and nothing else went wrong in the meantime.

I went to drive it today and it started making a loud clicking noise from the engine and idling shaky. Also, the oil pressure gauge started trembling as it went up which has never happened before.
The clicking noise sounded like metal hitting the crank case from the inside, happens once each rotation (i watched the rotation inside the oil fill), and just gets faster with acceleration.

I tried driving the few miles back home but it persisted and even worsened to the point of it sounding like something metal being tossed around. I had it towed home.

I did a valve adjustment back at home but none were unusually over tight. It was unusually difficult to get the engine to turn over using the power steering bolt. The belt kept slipping on the crankshaft. (In the past the engine turned over more easily by hand.)

Still have to put the valve cover back on and see if its still tapping. Feels like Im in over my head here. What are the possibilities? Broken crankshaft? Chain tensioner spring? Injector? Alternator shaft bearing?

Plz help. Im definitely fearing the worst. How do I diagnose? :confused:

I have no idea what the issue could be. But to clarify. Are you saying that the problem occurred on the first drive after you drained oil out of it? By how much was it over full and are you sure you did not drain too much?

- Peter.

Pull off your Vacuum Pump and check the Lever and Bearing that are on it. Look where the long skiny Bolt goes through the Piston and see the Pison is cracked around where the Bolt is.

Check the face of the Timer for damage.

Drain the Oil and drop the small Oil Pan and see if there is fragements in the Oil Pan.

Check the Oil Pump Chain Tensioner Shoe, Spring and the little Snap
Ring that keeps the Shoe in place.

Look at as many Oil Spray Nozzles as you can see.

If it turns out to be the Vacuum Pump:My question What in particular causes vacuum pump failure?
http://www.peachparts.com/shopforum/diesel-discussion/204187-what-particular-causes-vacuum-pump-failure.html

Rough idle and tapping noises could be as simple as a bad injector. Any possibility you allowed some dirt or other contaminant into the fuel system?

Yes, I Diesel purged it with three cans, and 1 can of libro moly additive. The dip stick had oil about 1-2 inches above the top fill indentations. I drained about 2 QTs of oil with a Top-Sider. The dipstick was and is still a little over full but I left it.


I will check out the vacuum pump.

And also check out the oil pan for any broken parts.

What am I looking for on the Oil Pump Chain Tensioner Shoe, where are the spring and little Snap Ring? Where are the Oil Spray Nozzles and what am I looking for?


No, the injectors might be 30 years old. Definitely no dirt. Possibly age. I was very careful doing the purge which would have cleaned them anyway, right?


Im now dealing with the car not starting by jumping the starter with a coat hanger at the terminal by the battery. I cant test if the valve adjustment fixed the problem because It wont start. It just lazily turns over like a low battery but jumping the battery from another car didnt work either. Is my battery dead?

I now have to
A: figure out why it wont start now
B: Get a NSS which so far has been really difficult in my area.
C: test if the valve adjustment stopped the tap
D: Oil and filter change w/ pan off and check the pan for metal

Have the battery charged and load tested while you are looking into the vacuum pump. You may have several unrelated issues. Where are you located?

I just want to mention this SAFETY item...

by using that method to start the engine....

YOU ARE BYPASSING the neutral start switch...

so just make sure the car is IN NEUTRAL....
because if it starts in gear.... it will go forward or backwards ....
we have had two farmers killed by their tractors running over them due to this kind of mistake.... you would probably be beside the car...and not get hurt.. hopefully....

If it were the Vacuum Pump wouldn't I have no vacuum pressure?

Located a NSS and currently slow charging the battery. In SF Bay Area. It wont start with a jump. The battery is dated 12/12. Is the battery completely dead?

If only the Bearing is damaged there still might be enough movement of the Arm to create adequate Vacuum. Your Car Your call.

Question ask from Post 5. I can't remember the disopsiton of the Oil Pump Chain Tansioner stuff as it has been about 5 Years since I had the Oil Pan off. I only remember you can see it if the Pan is off.

Here is what was in the oil pan after removal. Small metal shards. This is pretty much everything that was in there shown on this towel which gives you an idea as to the quantity of metal shards.
Any idea what part these came off or what else to look at with the pan off?

Thanks for the input

Oil Pump Chain Tensioner, Spring and Shoe look good.
Oil Pump intake mesh filter has some shrapnel in it.

Will be dealing with the battery, letting it charge overnight, installing new NSS, and look in the Vacuum Pump tomorrow.

Strange how a bunch of seemingly unrelated things fail all at once.

Is the debris magnetic or not?

Could be bearing Babbit. Could also be vacuum pump material. I think you really ought to entertain Diesel911's suggestion.

It all stuck to this magnet (on a money clip) as seen in the photo.
What does this mean?
Rod Bearing Babbit is possible.
I was seeing discussion of this on this thread: LOUD engine knock - Remove oil pan with engine in car? 300D | Mercedes-Benz Club of America

If its a thrashed Rod Bearing am I out an engine?

Will definitely pull the Vacuum Pump tomorrow and entertain Diesel911's suggestion.

Yes, if the bearing is so far gone that it's shedding shavings of itself and creating a loud knock, the engine is no longer usable. :(