Air bubbles in fuel pipes, 2.0 hdi

[Element]

Can anyone else confirm or comment on this situation for me...

2.0 hdi, 2005, Siemens fuel pump recently died on me so had new one fitted. However I have noticed (very small, but none the less present) air bubbles in the clear fuel pipes - firstly after the filter going to the pump and also after the pump in the other clear pipe. I questioned my local garage about it and they said in their experience, most diesel engines have air in the fuel pipes and not to worry about it. Still concerned, I asked my local Citroen dealer and they actually confirmed the same - it isn't a cause for concern... My father is a retired engineer and has pointed out that any air going into a high pressure fuel pump is a bad thing as it can cause 'cavitation' which leads to the destruction of the pump... (this might be the cause of the old pump dying) I don't know what to think now; I have tightened up the filter housing screwtop as much as it'll go and am pretty confident the air isn't getting in there. It must be coming from somewhere but don't know where.

So - what would you think? Particularly interested in other folks that have a Siemens pump with / without air bubbles - do you all see / have air bubbles present?

[Miguel]

I see this in my fuel lines in my 90bhp Siemens hdi. Has been like this years.

Enviado desde mi GT-I9505 usando Tapatalk

[dnsey]

I also noticed bubbles recently on my 2.0 HDi. No problems evident.

[Peter.N.]

Very small air bubbles won't hurt but if they get big enough they will stop the engine. If you can only see them after the filter, that's where the air is getting in, maybe impossible to cure, I don't think the Siemens system uses a lift pump which makes them more prone to this problem. If its running OK I wouldn't worry about them, the quantity of fuel and speed of flow through the pump isn't sufficient to cause cavitation.

Peter

[Element]

That's pretty much what I expected to hear, thanks for the info