Final round of quarterly refurb related queries. It's been productive, albeit grey inducing.

240D, 1981

ISSUE:


Low end engine thumping noise alleviated by engaging clutch. More of a thud-thud-thud-thud-thud, disappears when I press the pedal. Comes back when I release it. Engine smooth with clutch in.

CLUES:


*Happens in idle, gear box in neutral.

*Clutch in, noise disappears. Clutch out, noise reappears.

*Driving in gear, doesn't seem to be an issue.

*Issue began about a week ago when I replaced my motor mounts (lemforders)

*The engine appears to wobble side to side in a way that it hadn't previously, can see the oil sump wobbling back and from from underneath. Partially alleviated by pressing the clutch.

*Transmission mount replaced 3 months ago

*No T-mount installed (may have had one in the past?)

*Seated the new mounts by shaking the engine a bit, no issues bolting them down again.


Losing my mind.
Please, throw me a bone.

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1981 240D 4sp manual. Ivory White.

Might be a dead miss. Does it have good power?

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[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.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Has good power, but pressing the clutch would not prevent a miss if that were the issue...

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1981 240D 4sp manual. Ivory White.

2. My Transmission Makes Noises in Neutral

If the car is noisy when the transmission is in neutral, but the noise goes away when you depress the clutch pedal, it's possible the noise is coming from a worn-out input shaft bearing.




https://www.youtube.com/watch?v=mKCnLdYo73E

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96 E300d

Still fitted - however, those shocks only help dampen shutdown shakes.

Okay, that doesn’t sound great. Possible this would have anything to do with the way the transmission was balanced? Perhaps I need to readjust the mount?
Or total bad luck coincidence it happened right after I replaced the motor mounts?

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1981 240D 4sp manual. Ivory White.

Bell housing to engine bolts are not loose? Certainly if the problem started as soon as you changed the mounts would be signifigent to me.

Generally I find coincidence a poor second. Especially if I have done something and there now is an issue right after.

The issue you describe in neutral sounds like a clutch issue. I mentioned the bell housing bolts. As about the only relationship I might suspect. The alignment to the flywheel to your clutch may nave changed if those bolts where loose. Perhaps a long shot but easy to check.

Well at least they are still fitted - do you know if they actually have any damping feel to them?


(These dampers work all of the time - they can't tell when the engine is switched on or off}




You will nearly always get some form of bearing noise from the bearings in an old gearbox - you are most likely to hear the bearing noise at idle as the engine isn't making much noise - push in the clutch and the parts stop moving - let the pedal go and hey ho (!)


I think this is very unlikely to cause the lumpy problem you described in your first post.


I suspect the reason why you now have lumpy engine movement is because of the new mounts. They are more likely to be more elastic than the old ones which have had a life and were probably close to being rigid.


Diesel911 describes how / where the lumpiness could very well originate in post #3 - but I'd check the engine shocks just in case before rushing off measuring other stuff

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Things that cause shaking. Air in the incoming fuel. The Fuel Pressure Relief/Overflow Valve spring being compressed. Injector pop/opening pressures not within spec. Injectors.
Valve adjustment issues? Perhaps a valve is not seating well. Not sure if the 240d's have the valve rotator setup. A leak back test would tell about the valves. You can do a crude leak back test with air pressure into the cylinders in a position where the valves are closed (usually at TDC) and listen for air hissing in your intake manifold.
I don't know if you need the T-piece or not but if you do I believe it has to be adjusted.

Look up the Injector Cutout test and see cutting out one of the Injectors causes an obvious difference from doing the same to the other Injectors.

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84 300D, 82 Volvo 244Gl Diesel

Mercedes fitted shocks near to the engine mounts to help with this problem - are they still fitted?

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

* It only happens when the clutch is out.* Injectors have nothing to do with that, unfortunately. For what it’s worth however I have a brand new overflow valve spring and Greazer rebuilt my injectors not long ago.

These are valid insights, but this began with me changing motor mounts and is alleviated by stepping on the clutch. Logically, this seems like an issue of balance and stability

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1981 240D 4sp manual. Ivory White.

2. My Transmission Makes Noises in Neutral

If the car is noisy when the transmission is in neutral, but the noise goes away when you depress the clutch pedal, it's possible the noise is coming from a worn-out input shaft bearing.

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96 E300d

Lightly press the clutch peddle but not so the clutch disengages. If the noise goes away you could have a crank thrust bearing issue. With engine off, pry and pull the front pulley to check for excessive end play. You can use the factory spec for a measurement.

However, given the roughness of the engine you may be getting gear rattle from the transmission. This is where backlash of non loaded gears bouncing back and forth leads to noise.

In another thread some say to overfill the trans, while this may be a solution to more or less harmless noise, it might lead to lubrication issues. ( aeration. ) https://www.peachparts.com/shopforum/diesel-discussion/391894-717-400-getrag-5-speed-idle-noise.html

Regardless, if the engine is shaking that badly, fix that first.

Also, the title of this thread isn't very descriptive.

This is good.

After some more poking around, and even more importantly the passage of time, it seems everything has settled down a bit. The engine shake is gone (or my perception of it has been muted), I think I'm looking pretty good.

So I did the clutch test. Now that everything is a bit quieter and easier to assess, depressing the clutch is not actually affecting vibration. It's purely the sound.
And now that I think about it, I replaced the transmission fluid about 4 months ago. It was a little awkward down there and I was unable to replace as much fluid as I drained -I'd say by a difference of 15-20%. I'm going to attempt the over fill method by placing the right side of the car on ramps. Should be able to get a bit more in that way.

I think the obvious is that once you've replaced your mounts you start hearing things you previously couldn't.

Thank you for the wonderful ideas everyone!

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1981 240D 4sp manual. Ivory White.

For filling trans and rear ends, I use a top from a gear lube container ( like a mustard nozzle ) and a 6" piece of hose. This way as long at the bottle is facing downwards, you can squeeze it forcing oil upwards into the fill plug.

These tops fit most rectangular oil bottles giving one another option when space is restricted.

Also, make sure the hose does not come off the tapered top.

That is an excellent tip -thank you kindly

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1981 240D 4sp manual. Ivory White.