So I've noticed a good bit of crud accumulating around my high pressure pump. At first I thought it was collecting from a leak from the breather that I can't seem to completely fix, but this looks independent after cleaning it up.

I cleaned the top and front of the pump, but didn't see a source of the leak. Bottom is grimy as you see. Electrical connector for the small sensor was wet inside with what looked diesel (it was clear, not oil). But I really don't smell diesel anywhere. Almost looks like there's a leak between the pump and the head the way junk is built up.

Where do these usually leak? All the black grime made me think it was oil, but the clear fluid in the connector seems to say otherwise.

I've seen other threads that recommend resealing, but want to make sure I've diagnosed this correctly.

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05 E320 CDI
99 SL500
02 530i

82 240D SOLD
83 240D Euro 4spd SOLD
86 300D Euro Auto SOLD

Maybe answering my own question. Looks like they leak between the base plate and pump body?
https://youtu.be/VUX-mgVimj0.

Will pull and check.

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05 E320 CDI
99 SL500
02 530i

82 240D SOLD
83 240D Euro 4spd SOLD
86 300D Euro Auto SOLD

Ok, talking to myself more. Pump pulled, should have taken out the fan...but got the pump out. No screws loose on the back. I tightened them a bit more.

No smoking gun on why it's leaking, but it's leaking.

I think I'll call the local diesel injection shop tomorrow.

__________________
05 E320 CDI
99 SL500
02 530i

82 240D SOLD
83 240D Euro 4spd SOLD
86 300D Euro Auto SOLD

Mine started leaking at about 175k miles. Read a few things about how tightening some things could address it. Ended up just replacing it.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles
06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

It's tempting to just replace for sure. I think I will try to seal it myself and then go from there.

Tried to pull the fan and shroud, I haven't done that since the big 150k service. Do I need to pull the radiator hoses? Can't seem to wiggle it out otherwise. Opinions varied when I searched, but most answers were for a V6 or V8.

Working on this a few minutes at a time until the weekend...

__________________
05 E320 CDI
99 SL500
02 530i

82 240D SOLD
83 240D Euro 4spd SOLD
86 300D Euro Auto SOLD

Yes, there are reseal kits available. Is that what you're planning to do? Or just an effort to tighten as is.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles
06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

I'm going to try to do the reseal, the bolts between my high and low pressure side of the pump were all pretty tight. Don't think that alone will fix it.

__________________
05 E320 CDI
99 SL500
02 530i

82 240D SOLD
83 240D Euro 4spd SOLD
86 300D Euro Auto SOLD

Quick update...

Resealed the high to low pressure side seals and those on the sensors. After a hundred miles or so I'm leak free. Didn't open up the high pressure side, as I didn't have the piston tools. Splitting the two halves was harder than expected, needed some prying that I didn't really like to do on those surfaces.

__________________
05 E320 CDI
99 SL500
02 530i

82 240D SOLD
83 240D Euro 4spd SOLD
86 300D Euro Auto SOLD

axiom8-just did mine (359000) for the second time 2 months ago. MB sells part 012 997 07 45, large O ring, from the pump to the block. Does not sell other o rings. Bosch sells F 00n 201 973 for the entire pump. I just did the pump to the block. With the car running, mine leaked from the top of the pump-easy to see. I took out the fan-easy-to give more room. The diesel store sells the Bosch kit among others. Steve

Good info, when pulling the fan did you have to remove the radiator hoses? I couldn't get it out ... Hoses looked like the last thing holding me up

__________________
05 E320 CDI
99 SL500
02 530i

82 240D SOLD
83 240D Euro 4spd SOLD
86 300D Euro Auto SOLD