Ben - here's some of what was in the first 3,000 Yahoo posts on the topic of oil supply for the FI pump. Maybe others can add to this to answer your questions more specifically:
"Oil supply
Where my injection pump dip stick should be is a 14 mm nut with a slotted top. It appears very difficult to turn. Any insights as to why this slotted nut is where the dip stick should be. Did some dip-stick put that nut there?
Someone must have lost the dip stick. I assume they put a bolt in it's place with a nut to lock it so it would not leak/loosen.
On my car the nut is the dipstick. Took me 7 years looking at the diagrams to figure it out. I could not loosen it with a screwdriver, use a 14 mm socket.
I changed the oil in my 230 SL fuel injection pump. Instead of the T-shaped dipstick, my dipstick was on the end of a 14 mm nut. The nut had a screwdriver slot on the top. Using a window cleaner bottle pump, I was able to pump out 130 ml of old oil. I thought it might of had a slight gasoline smell but the oil didn't look diluted. To replace the oil you need a very small funnel. The small end should have an OD of 7 mm. Measuring the oil taken out and keeping and eye on the dipstick, it turned out to be a relatively easy task.
Will: best way to tell if there is an oil supply to the injection pump is to look at the left side of the block near the front. There is a small cross-section steel line that comes from there and goes to the right side of the injection pump body. This is the oil supply.
Pete Lesler: the fuel injection pump on the 250 SL also used a oil dip stick and a red oil filler cap.
I used a window cleaner bottle pump to remove the oil from the injector pump. On the top rear is a red cap with access to remove and add oil. Maybe the red cap has been replaced with something else as in my case. I pumped out about 130 ml of dirty oil. I am currently using 20 W 50 in the crankcase and the same in the injection pump. You will need a very small funnel to add new oil to the injection pump. The OD of the small end funner has to be 7 mm. I would get this funnel before I start.
I don't have a red cap on top of the pump, but I do have a metal cap that's about 20-25mm across. I will try the 14mm box end wrench for the dip stick bolt and the spray bottle tool for oil removal. So, you put the oil in through the dip stick bolt hole (7mm) instead of the large hole under the (red) cap on top? It's a shame you can't drain the oil out the bottom. I'll bet there's sludge and junk in the bottom of the housing that the spray bottle pump will not remove. Any way to really clean these pumps out?
I put the oil in the hole under the red cap or where the red cap should be. The hole size there was 7 mm (on my car). Maybe someone else can shed some light on this.
The red plastic cap simply replaced the metal cap of the earlier version. 250 SL had red.
Where did you syphon from, the small dip stick hole or the larger hole on top of the pump? Which hole did you refill through? Do you recall how much you put back in? I haven't removed the dip stick yet, is it accurate right off the bat, or do you have to run the car and measure again? Can you tell I haven't done this before? I'm always nervous messing with something for the first time.
I got a squirt bottle. I got the dip stick out with a screwdriver (no bolt edges, just a screwdriver slot and T-bar). After removing the dipstick I began to clean it. I noticed a driping sound. It was oil running out of the now open hole. When it stopped, there was a puddle on the floor about 12 inches (30 cm) in diameter. I removed the top cap (mine's metal, not red plastic) and began using the pump method. This was not simple due to cramped spacing and I would recommend the siphon method for others. The squirter pump went dry after pumping out 18oz (53 ml) into the bottle. I would say that this was a little overfilled, no? What problems could this overfilled state have caused? Have others found this problem on their cars as well? Once again, if this helps anyone identify how much oil I should put in, my F.I. pump ID Plate says: PES6KL70/120R11 609 33714. I will replace fluid in through the top cap and keep checking the T-bar dipstick for a fill level as I go.
Overfill interferes with the fly-weights at higher rpm fuel metering."
'69 white 280 SL
