Oh no, I have air in fuel lines... PICTURES!

[Doc Brown]

I love this site and I'm thankful for all the help I have gotten. I would have to say, my only complaint is not enough pictures.

Anyway, here is the situation. 1987 190D with a OM602.
The car will not start warm or cold without the aid of the glow plugs. Even when the engine is at operating temperature it will not immediately restart.

For the moment, lets assume the compression is good. The engine seems to run fine and there is barely any detectable blow-by.


The fuel tank return line was temporally replaced with some clear vinyl 5/16 hose so I could inspect the lines for air. As seen in the photo above there is zero air bubbles in the return line when the engine is idling and when the engine is revved. Everything seems fine.




On the other hand, the tiny pre-filter has a crap load of air in it. This filter has always had air in it and I figured it was normal. From what I gather, apparently this is not normal and needs to be dealt with... correct?

Anyway, if I shake the pre- filter around a bit while the engine is running I start getting air bubbles in the return line and the engine will start making a high pitch sound.

The fix....??

I'm assuming there is an air leak on the supply side of the fuel line. This car is very solid and relatively rust free so chances are the hard lines are probably ok. Could the air leak be coming from the connection to the fuel tank?