returning clear pipe from pump,fuzzy?

[Olivier]

Hello, what is the clear pipe going from the pump to the returning leak off pipes and that is attach to the filter?
I have some teeny bubbles coming from there, like a fuzzy drink. How can I explain, not separate bubbles but attach to each other and in slow constant flow from the pump toward the filter? ODD!
Thank you.
Olivier

 

[SilverSaloon]

is this when you have just switched off the car?

 

[Olivier]

Hiya,
No, the car was hot and running, didn't switch it off.

 

[SilverSaloon]

i thought you had changed all the usual o-rings on these pipes?

 

[Olivier]

they are all new ish. Done it about 7 month ago. I might need to look at it again though???
But what is this pipe for? Also there are more going to the pump, is there anyone who knows the functions of those? Othere diesel got an "in and out", on this filter there are several?

 

[SilverSaloon]

the pipe that also has the leak off pipe on is the return to tank pipe. if there are bubbles then air must be getting in. mine still bubbles occasionally - personally as long as the car doesnt leak and runs fine (seems to) then i dont worry about it. i dont think you'll ever get rid of all bubbles.

 

[Olivier]

I don't ming an odd bubble, I got some coming sometimes, but this is one is a novelty, never seen before... This is why I find it odd. I just wonder why is is attach to the pump and going to the return? Might be a pressure release for the pump?
Any idea?

 

[Dieselman]

As Silversaloon said, it's a leak off return pipe.

Check the seal on the pump side of the fuel shut-off valve. Air in the pump is bad as it causes retarded injection if there is too much.

 

[Olivier]

OK, there is another bother here, since I own the car there always as been this, when I stop it, after a wee while, the pipe going through the filter is emptying itself. Any ideas? This is odd as if I screw the filter more or less, the liquid moves up or down a litttle? Even with a new Oring into the filter screw?

Cheers.

 

[Dieselman]

It's due to a small volume of entrained air in the pre-filter which then flows backwards slightly when the engine is off.
It's pretty common and seemingly unsolvable, even with new O rings, filter, pipes and filter head..

 

[Olivier]

Pfff... I thought it was another bother. Thank you

 

[Smiley]

No bother - mine does the same but not to that extent.

 

[AANDYY]

Interesting, I've never noticed it before but I have the same.
Car is running OK, no bubbles in the clear pipe when running.
Could it be to do also with expansion/contraction, pics where took when engine cold a few Min's. ago

 

[SilverSaloon]

No bother - mine does the same but not to that extent.

mine too - but probably about half as much as yours

 

[spock500]

OK, there is another bother here, since I own the car there always as been this, when I stop it, after a wee while, the pipe going through the filter is emptying itself. Any ideas? This is odd as if I screw the filter more or less, the liquid moves up or down a litttle? Even with a new Oring into the filter screw?

Cheers.

Its prolly the non return valve located under the inlet manifold.

Sometimes there are two as on my OM605, one electric and one mechanical to stop the fuel returning back to the tank when facing up hill.

From memory theres one on each pipe, return and feed with the mechanical one being on the feed - not 100% sure on this though.

The leccy one sits under the water bottle on my W202 here,