Oil Change Capacity '87 300DT?
 

Have an '87 300D Turbo, 603.960 engine, has the side extension on the oil sump, and the remote air/oil cooler behind the front bumper. Has the original engine oil dipstick, black handle.

A few days ago, I took it in to the MB dealer in Hickory NC to have a one-time major maintenance done on it, with the idea of getting a good overall idea what kind of shape the car was in.

When he performed the oil change, the tech poured in the stated capacity in the service manual, 8 quarts, but apparently never checked the dipstick. When I came to pick it up, I checked everything over before leaving, and when I pulled the engine oil dipstick, the level was 1 1/2 to 2 inches over the max mark!:eek:

I grabbed the service advisor, he checked the dipstick himself, and immediately pulled the car back in the service bay to have it drained down. But both he and the tech were baffled why it wouldn't accept the stated 8 quarts, even allowing for the oil cooler and lines.

When I changed oil myself previously, on level ground and hot, level just at the max mark, the most that drained out was 6 1/2 to 7 quarts, and the same amount to refill.

A receipt in the glovebox from the PO stated the same amount for an oil change, 6 1/2 quarts.

The SA and tech were quite serious that even allowing for the oil cooler and lines, that engine should still have accepted 8 quarts to put it at or below the max mark. For the time being, I'm trusting the dipstick - I'd rather be a quart low than a quart too high!

Anyone have any ideas/info on this?

I'm very interested in this as I just bought the same car -- even to the mileage -- and I haven't changed the oil yet. The 603 engine is supposed to hold about 8 quarts of oil. The only question I can think to ask is whether the dipstick is indeed the correct one for that engine.

According to the W124 service library, it's supposed to have the dipstick with a black handle. Mine does, and from it's overall condition I'd say it's a good bet it's the original.

Barring an incorrect dipstick, there has to be a major physical reason as to why there would be this much difference from stated capacity.

This may not help at all but my 87 300D took the full 8-1/2 quarts that the manual says it should when I had the oil changed this week. How do I look up the full extension number for my engine? (603.????)

-Jim

My 603 holds 8 quarts on the dot. Thats just enough to cover the upper mark on the dipstick.

Was the filter replaced?

My SDL takes eight quarts just like the SD

Just a hair over 8 quarts.

Yep, replaced the filter when I did it and so did the dealer, same result - only 6 1/2 to 7 quarts to max level.:confused:

Just went to mbusa.com and joined owners online, submitted a tech question e-mail to their customer service dept. Described what happened when I changed the oil and what happened when the dealer poured in 8 quarts, asked them if there was a logical reason the oil capacity would differ so much from what's stated in the manual.

A nasty thought occurred to me - the oil pan for a 602 is one quart less capacity. If the oil pan for a 602 could fit on a 603, could someone have screwed up big time in the past and stuck the wrong oil pan on the beast?:eek:

Leaky Check Valve/Oil Pump?
 

Here's a thought - could a bad check valve or sloppy oil pump be allowing oil to drain back to the sump, that isn't supposed to drain back to the sump, making the level read high?

I've noticed every time I start the beast, it takes 2 or 3 seconds for the oil pressure gauge to respond, before it swings up to full pressure.

When I changed out the filter, the housing was bone dry, all oil had drained back down to the sump.

Is this out of the ordinary, or normal?

Ditto.

The 602 takes 7.4quarts, and since it's a 5-cyl, I can't imagine the pan would fit the 603.

Check Valves in Filter Housing
 

I believe I've found the reason why my oil capacity appears to be 1 1/2 to 2 quarts less than normal.

Looking at the oil filter in the FSM, in the base of the canister there looks to be a bypass valve, plus a return flow (check valve) in both the inlet and outlet. If one or both of these valves were leaking, especially the inlet check valve, it would allow not only the oil filter but also the supply piping back to the sump to drain down when shut down. If the bypass tube is leaking as well, this would just add to the problem.

Looking at the diagram, it appears that if the inlet check valve were working properly, when you removed the oil filter the oil should only drain down to the level of the stub tube - you should still have some oil left in the bottom of the housing. On mine when I changed the filter, there was no oil in the bottom of the housing - it was completely drained back to the sump.

The way my oil pressure behaves when starting up after sitting for more than a few minutes leads me to believe this is the case. After the engine catches, it's often a good 2 to 3 seconds before the pressure gauge starts to register, then a gradual swing up to full pressure taking about 2 seconds. Basically, the same effect as when you change the oil and spin-on filter on a gas vehicle and don't prime the oil filter first, you have a several second delay until the filter and lines refill and the system develops enough pressure to register.

I've thought of a way to confirm this. Note the oil level with the engine shut down, then pull the center bypass tube out of the filter cover. If the filter is full of oil, checking after 2 or 3 minutes should show a level increase on the dipstick as it drains down. If the filter and it's piping are already drained down (ie, check valves and bypass tube leaking), then there shouldn't be any change in oil level.

Well, here's another question for those of you with 603's -

When changing the oil, and you pour in the required 8 quarts, does it put the oil level well above the max mark on the dipstick? And then, after running the engine to refill everything, does that bring it down to the max mark?

On mine, there was no change in level between initially pouring the oil in, and the level after running the engine to refill the system. That seems to say that something is allowing the entire oil system to drain back down after shutdown. I'd written that off to being an MB oddity with it's particular setup, but in light of what's happened....

As you know the top mark is a red plastic thing MB stuck on the dipstick. 8 quarts brings it about half way up that plastic thing. Slightly over filled, I think the official capacity is 7.5 quarts. But since Delvac 1 comes in 1 gallon containers I just dump two in.

The oil filter canister should be empty when you remove the filter.

Problem is, 8 quarts put the level on mine 1/4 to 1/2 inch above the top of the upper plastic marker.:eek:

After the test I did yesterday, I believe the problem on mine is that the bypass tube and/or the check valves are allowing the filter and supply piping to drain back to the sump as soon as the engine is shut off.

I ran the engine up to normal operating temp, then shut it down. Waited for 10 minutes, then checked the level several times to make sure it had stabilized.

I then pulled the bypass tube out of the filter. If the filter was full of oil, this should have allowed enough to flow back to the sump to produce a noticeable change in level.

I waited another 10 minutes, and checked again. No noticeable change in level. Apparently the filter had drained down as soon as I shut off the engine.

This would jive with the pressure readings I'm seeing on startup. 2 to 3 seconds after the engine starts before the pressure gauge responds, then a gradual 2 second swing up to full pressure. Like it's having to refill an empty filter housing.

A leaky bypass tube, from a comment I saw on another thread, might also explain the continued lifter clatter even with Mobil 1 5W40 synthetic in it now.