I noticed something weird about my 300SD. When the engine is cold, it idles around 600rpm. After you drive it for a minute or two, it idles around 7-800rpm. Is this normal behavior for these diesels?

Additionally, when the motor is cold, idle oil pressure is always on "3". After it warms up, it drops down to 2-2.5. My 77 300D does about the same, but drops slightly lower when warmed up. What is the normal behavior for oil pressure?

I am not sure what year you 300SD is. If it has a 617 Turbo Diesel The last Paragraph is normal. At hot idle I believe you are allowed to have as low as 0.5 bar.
However, I don't know if the Gauges on them can measure that low accurately.

The change in rpm from low idle when cold to a higher idle is normal but I think the range you have is slighly abnormal.
There is a sticker under the Hood that has what the Idle specs are. You could raise it to the Higher end of the Idles specs.and see if that cures the problem.

I am going to add this here; the little O-rings on the end of that Tube on the Oil Filter Cap can change the Idle Oil Pressure.

Thick Oil can cause a lower rpm till it wams up and that is also Weather dependant as far as the outside temp.
But, also if your Engine is not well tuned; especially concerning the Injectors it can run better after it is warmed up because the Fuel is going to burn better and more evenly.
If the Pop Pressures are out of balance it can produce uneven idle.

You also might try backing off the Governor Idle Pin/Rack Damper. Adjust your Idle and then re-adjust the Rack Damper. From what I have read People tend to run the Governor Idle Pin/Rack Damper in too far (perhaps because then need a new Gold Colored one) and they have their idle speed haing soley on the Governor Idle Pin/Rack Damper.

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84 300D, 82 Volvo 244Gl Diesel

Normal. My 240D even has a dash switch to increase the idle when cold, because otherwise it's liable to stall out since cold idle is below the RPM where the engine can self-sustain.

As far as oil pressure, oil thins as it heats up, and therefore its pressure will drop. Imagine forcing molasses through a straw vs olive oil -- a greater pressure is required to maintain a flow of molasses.

As already stated the oil pressure is normal. Anything over .5 bar is okay at idle as long as it pegs once you hit the go pedal.

Thanks for the responses. I recently replaced the motor mounts on this vehicle and am wondering if the engine moving is normal at idle. See the video: 300sd idle - YouTube

Agree on oil pressure. My 84 300D drops to 2 bar at idle when hot. My 85 300D holds 3 bars even hot, but that engine appears almost new (no blow-by). What causes lower oil pressure is worn bearings with larger gaps.

Hard to tell in the youtube video (low frame rate). My engines have less large-amplitude, low-frequency vibrations and higher frequencies that like to excite the air cleaner (why I switched to 85 CA frame-mounted filter). My engines are probably a bit quieter, but hard to tell in a video. I have seen some 300D's that are so quiet you can barely tell they are a diesel (could have a Chevy SB?). Others, I can hear clearly when they come to the stop sign by my house, and notice them. My 85 300D used to sound like that, became hard to start in winter, then engine failed at 330K.

What caused the engine to fail? I'm about 75K away from that on my 300D and about 130K away from that on my 300SD. At the rate I drive, it will take at least 10 years for me to add 100,000mi to each car.

Aren't vibrations more down to engine mounts and tuning (valve clearances, injection pump condition) than internal engine parts?

Concerning the sound.
I have no Hood Pad on mine and if someone uses Additives that increase the Cetane the Engine can sound quieter.

People also claim the Alternative Fuels are quieter.

I know timing also makes a difference. When I advanced my Fuel Injection pump Timing to 27 degrees BTDC it was a lot noiser at idle; so much so I did not like it there and changed it. And, the same applies when the Timing is late.

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84 300D, 82 Volvo 244Gl Diesel

As Bill said, the video doesn't show anything.

You said your engine is moving. If that means a sort of loping or rythmic side to side movement that you can feel right through the car, that is probably the adjustment on your rack damper bolt, which is at the back of the injection pump and can be tuned to remove the loping on the turbodiesels. Do a search for more info.

If your car has the original silver bolt, it most likely needs to be upgraded to the later gold model, which takes out more oscillation. If the movement shows up when the car is hot, or especially after highway runs, this is your culprit.

IF the movement is vibration or buzzing, then you have another issue.

What brand motor mounts did you install? Whunter has actually seen an off-brand mount fail immediately after installation, before the car was even backed out of his bay.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I installed Lemforder mounts. The car drives great with no vibrations. I'm just wondering if the side to side moving is normal. When watching the video, take a look at the power steering pump area and you can see it. Maybe it's because the mounts are new and haven't had time to "settle" in?

I saw another 300SD video on Youtube. The poster claims replacing the delivery valve fixed his "moving/swaying engine" problem.

The engine sounds normal in person. The camera just makes it sound garbled.

I've got more to add on this issue. This morning I started the car and it was around 20F outside. The car started okay, but ran at about 500rpm for a a second or two. I immediately gave it some gas and after releasing the gas, the RPMs returned to normal 600ish-750ish.

What gives?

PS: On a positive note, a valve adjustment cured the vibration issue.

It was cold so not all the fuel was getting burned, causing the low idle and probably rather a lot of white smoke out the tailpipe. Once you got the combustion chambers a little warmer, the combustion efficiency went up, releasing more heat and doing more work so you're idle went up.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.