I have an '80 300d.
Does the fuel primer just unscrew?
Is the new replacement just as good as old?
What is the line that comes up from top of oil Pan and runs up under air filter and why would it be leaking oil?

Yes.
Better
Oil separator return line. O-rings are bad.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

#1. Yes.
#2. Yes.
#3. Oil accumulator return tube.
#4. Bad O-ring at the top or bottom, and/or the center tube brace bracket broke off/was not mounted = loose tube rubbed against something until a hole formed..







Have a great day.

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1985 300SD
1983 300D
1984 190D
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I think you have a leaky "screw type" primer pump which is spraying fuel on your hands when you are pumping it, and as soon as you quit pump it allows air into the system with the same leaks and then your fuel system is full of air. Now it needs great quantities of air to run, but it has to come in at the right place, and the IP is a bad place for air. Get yourself a new style pump that does not have a screw top. It will solve a lot of problems. I have and extra, (brand new Bosch) will sell cheap. PM me

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Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

Now I see this is your third post on this subject. To get good answers from the good folks on this forum, keep your questions all in the same post - just use the "Reply to Thread" space at the bottom of the page. Yup, even if replying to your own posts.

__________________
Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

Click on Buy Parts on the top of this page to by a primer pump.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Please read this thread.

617 engine, replacing the oil separator check valve in the upper oil pan.
http://www.peachparts.com/shopforum/diesel-discussion/122057-617-engine-replacing-oil-separator-check-valve-upper-oil-pan-post2754703.html

Here is the correct part with adapter.

Fastlane: DIESEL PRIMER PUMP. NOTE: THIS BRAND HAS A 16 MM THREADED FITTING, AND COMES WITH A 22 MM ADAPTER. CAN BE USED FOR MODELS WITH EITHER A 16 OR 22 MM RECEPTACLE ON THE FUEL PUMP.
http://catalog.peachparts.com/item.wws?sku=0000908850


Here's my payback! Diesel Primer Pump Replacement
Here's my payback! Diesel Primer Pump Replacement



.

Yes starting to figure out how to get around this a little better. I really appreciate the help. It's great having someone to talk to other then my busy mechanic. Maybe I won't sell the car now. I went to this '80d that sat in a friends back yard, on the grass, under a tree for 5 years, from a '90 420sel that was owned by a little ol' lady...

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1980 300d

Welcome to the forum. A great place to get and give help.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I pulled off the air filter tray to change o ring to oil return line and saw the intake manifold has about a half inch of greasy goo in it....?

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1980 300d

I pulled the manifold off to have it cleaned...any secrets to remounting it...
Tork amount or configuration?

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1980 300d