I'm running a 5-40 synthic and it's very runny. This is the first time I've run a synthic oil and it looks like the oil level is a little higher than when I filled it a Thousand miles ago. I fear maybe the injection pump is leaking into the oil. I had the same problem on my grandfathers tractor that ended in the death of the motor. Funny thing is it was leaking/ burning oil at the same rate as the injection pump leaked.

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84 300sd 2.47 dif 360k
26 mpg needs lots of love
given to me in pitty

89 civic hatchback auto 140k
33mpgs soon to be low to mid 40's
been in the family since mile 1

85 300d with unknown knock. driven over 30k with knock and still going. sold for $800

I believe it is possible but quite rare...how does it run?

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Could the lift pump seal be compromised? This could introduce fuel to the oil. Very hard in my opinion to make a determination something is going on. Reading a dipstick in different locations will produce somewhat different results. Can you smell diesel fuel on the dipstick?

You could send out a sample for evalution. Unless it is really pretty certain. Viscosity of 5w 40 at least to me sounds a little too thin for these diesels in summertime running. It may protect like a forty weight at operational temperatures it was designed for but will not have the viscosity of a forty weight. To compound this the oil in these engines may or may not run at as high a temperature as the oil product manufacturers intended. The viscosity of multi grades increases with temperature.

If all your trips have been just around town you may have made some increase in condensate level as well. Have you been out on the highways?

Sounds like a case for some oil analysis, from someplace like Blackstone Labs.

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1979 300D 040 Black on Black - 1985 300D Maaco job (sadly sprayed over 199 Black Pearl Metallic) on Palamino

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Yes. The little O-ring in the Picture is what can cause the Leak. The Valve Kit that Pelican Parts sells does not have the O-ring.

http://www.peachparts.com/shopforum/showthread.php?t=215770
Bosch FP/K22MW22 Feed pump There is a repair kit for these pumps. Bosch part number DGK301 The kit covers FP?K KE and KS pumps includes more parts than you'll.
The above is the Complete Kit+ extras because the kit covers other models.
I bought the Valve Kit from Mercedes and scrounged up the O-ring from the local BMW Motor Cycle Dealer.
There is also some sites that sell generic kits.

The O-rings listed below are supposed to be Viton but read the thread to be sure.

Lift/FUEL SUPPLY PUMP TINY o-ring
Bosch lists now 2 440 210 002 (MB 010 997 86 48) as replacement to the original black(perbunan?). And yes,the replacement is Viton.
The 5mmØ x 1.50mmØ 'O' ring is located in a groove in this bore and prevents engine oil in the IP from being sucked into the fuel re-circulation circuit. In most cases this O-ring has either hardened and broken up or completely disappeared.
http://www.peachparts.com/shopforum/showthread.php?t=261822

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84 300D, 82 Volvo 244Gl Diesel

That is a good idea but He could get a Rebuild Kit for his Fuel Supply/Lift Pump for the Cost of the Analysis and change the Oil and see what happens.

The only other place Fuel can get into the Engine is the Injectors. If an Injector was bad enough to do that I would think it would show up as some sever Nailing after start up.

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84 300D, 82 Volvo 244Gl Diesel

Diesel911, I have a spare lift pump. Should I be able to compress the cam by hand on the bench to see if it moves or is the spring really stiff?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Possible coolant getting into the oil?

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wouldnt the oil pressure be too great for this to happen? wouldnt the opposite happen, oil getting into the fuel?

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1981 NA 300D 310k miles

Once the Pressurized Oil gets past the Tappets it is not pressurized and there is a big port at the top of the front Bearing Cap that lets the Oil Flow out.

On other Bosch Inline Fuel Injection Pumps If the little O-ring gives out the Fuel Gets into the Crankcase.

However, at least 2 Members have said that they had Oil loss and could not explain were it was going and Rebuilding the Fuel Supply/Lift Pump fixed that.

And, when I worked in a Fuel Injection Shop I have never experienced the Lift Pump sucking in Oil from the Fuel Injection Pump so for Me that muddles the issue.

However, there is only 2 Places where Fuel can get into the Engine. By way of the Injectors or the Fuel Supply/Lift Pump. So I think the OP is left with a process of elimination.

It could be that if the O-ring gets old and hard the Lift Pump Sucks in Oil. If the O-ring is so bad it is nearly gone it could he Fuel leaks into the Crankcase.

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84 300D, 82 Volvo 244Gl Diesel

The Spring is stiff. Try grabbing the Pump and pusing the Roller or Rod end of the Pump against a Wooden Door frame. That way you can sort of lean your weight on it.
It is possible for the Piston to be rusted in place.

If you remove the 30 something mm plug you can remove the Piston and the Spring.

If you remove the Large Plug on the Pump you will not have another Crush washer for it and that Crush Washer is thin and if it sticks it is hard to remove it with out bending it. I just put some Thread Sealant on the Plug and screw it back in.
If you use Blue Loctite try to get it only on the back 2-3 threads.

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84 300D, 82 Volvo 244Gl Diesel

The funny thing is this is the longest the motor has held oil. I just replaced the head gasket 2 months ago and I haven't seen a coolant drop. I believe I have a fuel pump in my truck I could try and see if it it helps. The motor oil smells like diesel exhaust and it taste like nothing. I figured I might be able to taste the diesel, but funny enough the synthetic Rotella doesn't taste like anything. I've sent out for a kit from the lab you guys recommended and it should be here in a week. I'm thinking about removing some oil and then marking the dip stick half an inch above the new level to see if it changes. Let's hope I'm just crazzy.

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84 300sd 2.47 dif 360k
26 mpg needs lots of love
given to me in pitty

89 civic hatchback auto 140k
33mpgs soon to be low to mid 40's
been in the family since mile 1

85 300d with unknown knock. driven over 30k with knock and still going. sold for $800

We'll I sucked out a gallon and a half of oil before it was on the right spot on the dip stick. Where can I find the sealing ring.

__________________
84 300sd 2.47 dif 360k
26 mpg needs lots of love
given to me in pitty

89 civic hatchback auto 140k
33mpgs soon to be low to mid 40's
been in the family since mile 1

85 300d with unknown knock. driven over 30k with knock and still going. sold for $800

Not sure if this is what you mean
Lift/FUEL SUPPLY PUMP TINY o-ringBosch lists now 2 440 210 002 (MB 010 997 86 48) as replacement to the original black(perbunan?). And yes,the replacement is Viton.

A Bosch Fuel Injection Shop would be or maybe the Dealer since there is a MB part number for that

I bought a regular rubber on from a BMW Motor Cycle Dealer and had to wait a week for it at $1.75
BMW motorcycle parts 5x1.5mm O-ring, cold-start enrichener shaft, part# 13 11 1 257 819

Or you can buy the compelet Fuel Supply/Lift Pump Rebuild Kit
The Turbo Diesel kit is Bosch kit# DGK301
The copies run a totlal with shipping included about $15 the real Bosch Kit is close to $30 some add shipping some don't
The Kit for the M Pump before 1985 is DGK128 but you need to verify that as I am not 100% Sure.

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84 300D, 82 Volvo 244Gl Diesel

I ordered the kit. its impossible for the injection pump to leak diesel into the oil right? At least that's my understanding from your posts. Only the injectors and the fuel lift pump and leak into the crank case

__________________
84 300sd 2.47 dif 360k
26 mpg needs lots of love
given to me in pitty

89 civic hatchback auto 140k
33mpgs soon to be low to mid 40's
been in the family since mile 1

85 300d with unknown knock. driven over 30k with knock and still going. sold for $800