Fuel in the injection pump, NOT where it should be

[MAF]

Playing with my 1971 300 SEL 6.3,pulled the dipstick, on the fuel injection pump,darkish oil starts flowing out the dipstick hole.I siphoned out about a half a Campbells soup can of fuel /oil mix.
I then added oil , through the cap,as mix continued to ebb out of the dipstick hole.I capped both, and started the car.Ran fine.
How much trouble am I in??

[johnathan1]

I've always thought that the injection pump shares an oil supply with the engine...but maybe that's just diesels?

[MAF]

I have just changed the oil,and it has no fuel odor,and as I understand it,(maybe incorrectly), the crankcase, on the injector pump,has it's own,thus the dipstick.The oil in the injection pump was noticeably gassier, and dirtier.

[vox_incognita]

Happens if not serviced for a long time-same thing on diesel IP with independent sump.That`s why I change the oil in IP every (other)engine oil change.

[ja17]

The Mercedes 300SEL 6.3 has its own oil supply separate from the engine oil. The oil in the unit can become contaminated with fuel, when the level becomes too high it can cause problems.

Othe MB models did have an injection pump which shared circulating engine oil.

[wbain5280]

If there is too much oil in the sump, the goveror counterweights won't operate properly and the car will run poorly.

[Arthur Dalton]

What you want to do is get ALL the contaminated oil out of the pump, as it causes pump wear. And you can not do that thru the fill hole. It must be evacuated thru the dip-stick hole in order to get to the bottom of the Pump.
Some use different arrangements to do that , but here is an easy and inexpensive way that I have used for years...

Take a clear jar and poke/drill two holes in the screw-on top .. [A glass mayonaise or pickle jar is fine].. Push a long rubber vac. hose thru one hole about an inch or two, making sure it's fit is tight enough to seal at the cap hole . screw the jar cap back on tight to seal.
On the other end of vac hose , slip hose on to a thin plastic dip/suction line from any squirt bottle. [ Windex, etc.]. Put that dip tube into the pumps dip-stick hole , making sure you are all the way to the bottom of the pumps reservoir. [ Make sure that tube is long enough to reach the pump bottom and stll sticks out of pump hole, just to assure that in case the vac line comes off the tube, tube can not drop into pump. ]
Now . take any shop vacuum cleaner and place the suction hose over the other open hole on the jar, creating a vac in the jar...the fluid will suck right out of the Pump and drop into the jar before reaching the vacuum cleaner hose and you can see it ...Simple, cheap, and fast.
The last thing is to take the oil fill cap off the pump before evqcuation of oil, and clean the filter in the cap while you have it off..That has to be clean b/c it is the Pumps Vent for the Oil reservoir.
I do this evacuation after warming the car up to temp so all contaminents are suspended in the evacuated oil..........then re-fill res w/new oil thru fill cap hole , but do not excede the dip-stick capacity indicator line. [ reading taken with dip-stick screwed in]
The lower seals in the pump are stating to leak, but frequent oil changes are usually sufficient and you can tell when it is re-occuring b/c the level will Rise...............
The jar is just a simple oil drop tank princible and if you keep that in mind, yoo can use anything that uses the basic idea of the jar and any vac source....
I have a more pro set-up that uses a vac pump, etc, but a shop vac and jar are all that is needed and most DIYers have them handy. This makes the oil change much easier and b/c it takes so little oil , it is not a bad idea to do it on a yearly basis...or when it looks dirty and the level starts to rise.
Cheap pump Insurance...............
It always amases me on how many owners are not even aware of this dip-stick/oil reservoir system used on early Bosch MFIs......

[MAF]

Arthur- Thanks!! I kind of did the reverse of your method.I put a clear tube down into the fill tube hole, and with the dipstick out, blew into the clear tube.A little messy, but seemed to get the old fluid(?) out.
Does the cap come apart,or do I just clean it up as best I can ,(like I already did),by wiping thoroughly with a cloth?
I am going to change the oil again,using your method-ingenious, and a lot less mess.I refilled with Castrol High Mileage 5W30, thinking the seal swellant properties of that oil may do the pump seals some good.

[Arthur Dalton]

I just clean the cap with kero and blow it out.
Run your new oil for a short time and then try the suction trick...I use straight 30/Non Detergent oil in the pumps.

[mercmad6.3]

I would also add that Joe is not quite right above because the 6.3 pumps has a oil feed from the engine,it's that thin line on the right side of the pump body. it pressurizes the fuel elements both lubricating and sealing the fuel system. Because unlike a diesel there is no lube qualities in petrol.

Now ..eventually the seals under the injection elements wear out and the pump cam chamber fills with too much oil. This gets into the governor section via the rear bearing. You can tell when the pump is on the way out when lots of oil starts appearing around the pump,leaks out the solenoids and generally leaves a mess on the ground under your car. The pump governor should evacuated every oil change . Most pumps now been modified and have the short dip stick which means the oil is level with the top of the hole in the housing so the oil level means nothing. If you undo the plug and oil pours out you have too much. Simple. A better gauge is to remove the large round nut with the idle thumb screw adjustment on it and let that be the oil level.

Fuel smell in the lube oil is not the main problem cuased by a pump on a 6.3,that's usually too rich a mixture or leaking start valves. It takes a very tired pump to leak fuel badly into the sump oil .I have worked on them where the fuel was stained with oil when I undid the injector pipes.
Either way it must be fixed because rapid engine wear is the result and 6.3 pistons and rings are getting both expensive and hard to find in the correct compression ratio .

The governor has it's own lube oil because if it were fed from the engine it would fill completely and the governor would be churning in oil restricting it's movement ,which is what happens when it gets overfull.
I have seen a few pumps which have had a hole drilled in the front so the excess oil can return faster to the sump. This doesn't work because the timing chain actually pumps oil INTO the pump via any hole in the front which is why Bosch never did it. Excess oil is expected to drain via the front bearing ,keeping it lubed.
The worst i have seen is a hole drilled in the governor cover and a hose running to a hole drilled in the block to allow the excess oil to run back into the engine.
The easiest way to avoid these problems is to change the oil OFTEN .

[MAF]

Mercmad- Thanks!! I am getting ready to do emissions, to license the car.
I need to be able to lean the car, over the entire range.I see in another post ,that the altitude is where to lean it out.I would also like to know where the push in idle mixture screw is.Should I pull the cover ,on the governor, to see what is going on with the oil?
By the way, I was looking at Ebay the other day, and I sold you something, sometime ago.Had I known you were going to be so helpful, I would have given it to you. LOL LOL
I have to be licenced by Feb 26, or I can't park the car on the street anymore.Besides, I love to drive it!! These things are addictive!
Thanks ,so much ,for all your help!

[mercmad6.3]

Hi,the idle adjustment is at the rear of the pump,if you look down behind it you can see it there'.As you have already checked the oil in the pump you can now go to the next steps.
But first some basic rules

1/Never touch the injection until the ignition is perfect
leave the compensator alone!
2/ Make sure all valve clearances are to specification.
leave the compensator alone!
3/ Examine the linkage from the throttle body to the pump.
Any wear in those ball ends will cause things like excess fuel ( rich running) and hesitation on aceleration. Aceleration should be instant . The quick way to ensure correct linkage positioning is to ensure that the pump is at throttle stop position and at the same time the throttle is also closed completely and no movement in the linkage is detectable. Read through the m-100 site for instructions on making a guage to measure the movement thoughout the throttle range.
leave the compensator alone!.
4/ Check both cold start valves tp make sure they are not leaking internally. On the rear of each valve is a small bolt,with the igniton on and the car not running ,undo this small nolt (8mm on some) and if fuel drips from there you have a leaky valve. This must be repaired before progressing further.
5/ Once the cold start valves ( there are 2 one on each manifold) are correct, you then need to use a CO meter,it's hopeless even thinking about tuning a 6.3 without one.
6/ The engine must be hot ,a minimum of a 5 mile drive is needed to vget the car up to normal temperature of at 175F or 80 C.
7/ If the car is running hotter than in a normal drive or heating while idling,the thermostat for the radiator must be checked and the fan clutch examined. Again,it's a pointless exercise if the car is not in road driving state when tuning the mixture.
8/ Remove the rubber hose running from the throttle body to the air cleaner. Below this is another 1" hose. Remove this .Start the engine and while it's at running temp. feel the end of the hose. if there is any vaccum at all the fuel pump thermostat is fualty and needs to be replaced.
DO NOT ATTEMPT TO ALTER THE SETTINGS OF THE VALVE UNDER THE THERMO TO CHANGE THE VACUUM EFFECT.
It's far easier to simply replace the thermostat.
Once you have done all this check your CO readings. Factory settings are most important. Becauase this is a mechanical system it runs at a higher CO level thna most people would realise ( Kjet .05 as an example) .
The correct setting at 600 RPM is approx 4.5 . When you put it into gear with the air on the CO will rise because it will still be pumping the same amount of fuel but drawing less air .
Keep your foot off the brake pedal when doing this because that in effect cuases it to read leaner. A leaking booster completely alters the readings... to read too lean.
You can test the load range readings yourself with a CO meter under load in 3rd gear (ONLY!!) for a few seconds at 40 mph.
With your foot on the brake ,and some one to read the CO meter on their lap in the car, place your foot on the brake and hard on the acelerator for around 5 seconds. You should get a reading of approx 3.0 Co.
Anything significantly more ,and you have followed the above correctly , then the pump 3D cam is worn. it means a rebuild.
Smoke under hard aceleration is normal ,Not big clouds,but a puff of brown smoke as the pump delivers slightly rich for a few moments. Good luck with the emmisions test.