[MickyP]

Does a small amount of air in fuel system bleed itself through after the engine's been running a while or is it always there unless manually removed with the hand primer?

 

[davehg]

as no-one's replied, I'll give my thoughts! In general, air bubbles are passed through the system during bleeding. However I suspect you can get problems with air locks if the piping has loops in it. Also if there is a poor connection somewhere then air can be drawn in continually.

 

[MickyP]

I agree. But suppose an injector was leaking or dribbling when idle. Would the pipes be purged of air when the engine fires up next time (if it does!)?

 

[davehg]

once the pressure is released through the leaky injector that should be it - unless air can get in somehow??

 

[davehg]

why do you ask?

 

[MickyP]

I have two diesel 206s and one has always missed a bit when starting, accompanied by a puff of smoke. Fine when it's very cold as glowplugs kick in and fine when warm. Just the bit in the middle. When I bought it I looked at glowplugs and fuel rails but it's always displayed the same issue, and was potentially getting expensive, so I just left it. Now after some serious primer hand pumping (o-er!) for another issue, it starts clean as a whistle. Now that may be a coincidence (it's quite mild at mo), my mind playing tricks, etc, but I thought I'd ask the question.

 

[windy1603]

As long as there is no air in the HP pump is should self purge any air that gets into the injector or injector lines.

It could be the leak off pipes or seal letting air into the system, a poor seal on a joint in the fuel system or chaffing of the pipes on the rear of the engine. You could try grease on the filter and other obvious joint to see if it improves as that will seal the pipes short term or if return pipe issue some people fit a non return valve to stop air leaking back into the system