My 240D has begun collecting air in the plastic primary filter. I find that I can use the primer pump to push some of it on but not all. Often a bubble will rise from the filter inlet. I tightened the hose clamps in the engine compartment but there is no improvement. The car sits in the garage for a week and there is no fuel puddle so I wonder if the fuel pump is failing???
Any tips? Chris
It is likely that your primer pump lets air in also. So I would change all your hoses and the primer pump to eliminate these suspects.
I was going to ask a similar question today, but my issue is much more dramatic than the OP's. 1979 300TD as many of you may remember...
When the car is running, there's a constant stream of bubbles going into the fuel prefilter. The hose leading to it is pretty old and beat, and I'll be replacing it soon, but if I'm going to get soaked in diesel fuel I want to know what all to look at. Is the system closed, insofar as if I don't purge the air properly it'll keep circulating, or is a lame-o purge after changing the filters going to work itself out over time and the air should just "go away" all by itself? I wouldn't think that in my case the hand pump leaking could cause this effect since the hand pump is on the other side of the prefilter. Could my fuel pump be going bad? ...but it looks like the pump is the part that the hand pump is connected to, sooo... The air appears to be coming from the tank.
...I suppose I'll just go and swap out all of the fuel lines and then see what I get. I never looked at the prefilter while the engine was running before the filter change, but I'm pretty certain there was a smaller volume of air in it.
When I did the filter change, I pumped and pumped and pumped, but didn't get the point that I was supposed to release the 'out' line from the main fuel filter. Could that fact be causing me these problems? The car runs fine, but it doesn't start up as quickly as it did before the filter swap. Before the swap it would always fire on the first or second crank, now it takes two to four to start when the engine is cold.
Thanks for any advice.
-tom!
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