Please help me!

The return line of my IP always full of air bubble. I change other line with clear new vinyl, copper washer on banjo....

I see no leak anywhere. I try to crack injector, adjust bypass valve,strecth the spring and replace ball.

I change before both filter, dismanteling the lift pump (all seem ok) and replace the priming pump. No air bubble before the IP... Just after the bypass valve banjo.

Can i make paper gasket between the starting of the injection steel line & the casign of the IP? I see no leak at all.

Thanks all for your knoweldge.

What difference does it make? It's just sending air back to the tank so it shouldn't effect the running of the motor at all.

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1985 300TD 185k+
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1984 300SD 315k--daughter's car
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If you can see the bubbles while the Engine is ideling try slowly moving the Plunger on the Hand Prrimer and see if the stream of Bubbles changes.

Also try moving Hand Primer as if you where pumping to bleed the system and see if there is any effect.

Squirt some Engine Oil around the base of the Hand Primer where the Copper Crush Washer goes and see if that has an effect.

You spoke of changing the Filter but did not say you replaced the 2 sections of Fuel Inlet Hose. The Auto Part Chains stores sell regular Fuel Hose that is rated for Diesel Fuel as well as Gasoline the ID needed is 5/16" it will have SAE 30R7 on the Hose.

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84 300D, 82 Volvo 244Gl Diesel

These come as an assembly with fittings, because the tube joints must NOT leak.

Replacing only the nylon tube and getting it to seal correctly is difficult or impossible, without using fuel injection hose clamps at every joint.

I assume you replaced more than one nylon tube???

http://www.peachparts.com/shopforum/mercedes-parts-reference-library/185880-om616-617-912-617-952-plastic-fuel-lines-injection-pump.html


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@ kerry: yes, in theory...Well, the engine knock hard: really air go in injector...

@ Diesel911: I try, no really significant effect...the bubble flow are made with tiny bubble stream..Can stop for 3 or 2 second and restart. When the engine run on the iddle, the bubble can change at every time, in number and size.

@ whunter: Yes, a mix of strong hand for insertion and tactfulness with heatgun can made a good sealing result. Is not the first time i change some or all nylon tube...and the trouble start before i wan to see clearly the coming fuel.

In the past,i work on many saab: i make strong work experience with strange and hard-to-find loss of fluid or invisible air-taking..

What going inside the IP before no.185 (see on OM616, 617.912, 617.952, Plastic fuel lines, injection pump)? For what the air bubble come from this hole? Can see more detail about inside of the IP?

I think if injector connection take air,are probably squirt fuel?
Nylon tube squeeze on banjo too?
Filter and their connection, same?

Good new, air not come from the tank...
Bad new: is my winter car: scary to broke the IP and have to take bus with my son for day nursery..

I think is impossible, a worn o-ring (thanks to biodiesel3000 for the pic) :
http://www.peachparts.com/shopforum/attachments/diesel-discussion/96294d1317516015-papas-got-brand-new-om617-ip-play-delivery_valve.jpg

That is not a common failure.

seal ring
MB# 0079973448


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Well, how can find seepage of air on IP? Remember, engine knock and heavily move: put oil on some location for leak evidence are fastidious.

All seem ok: just a big flow of air bubble coming at no.185:

http://www.peachparts.com/shopforum/attachments/mercedes-parts-reference-library/43435d1177101287-om616-617-912-617-952-plastic-fuel-lines-injection-pump-plastic-ip-tubes_dfg456.jpg

Before dismanteling more, really need detail look of interior IP...