Normal Air Bubble in Prefilter - PeachParts Mercedes-Benz Forum

Haggurd · #1 07-24-2017, 11:53 PM

Hello all,

I'm new to the world of diesel vehicles and I've just completed a fuel tank flush and complete flexible fuel line replacement including the intake screen and both filters on my 240D. I bled the car using the newly-installed Bosch primer pump and by cracking the hard lines at the injectors and cranking. The car appears to be running phenomenally.

I noticed a small amount of air in the prefilter and was wondering if this amount is considered normal. Despite continued pumping, running, and manipulation of the prefilter I cannot seem to get this last little bit of air out. Picture for reference.

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Diseasel300 · #2 07-25-2017, 12:15 AM

There will always be a small bubble in the prefilter, it's completely normal. Now if you see foam entering the filter or the bubble seems to grow you may have an air leak somewhere, but otherwise a bubble is a normal part of life.

Haggurd · #3 07-25-2017, 12:17 AM

Quote:

Originally Posted by Diseasel300

There will always be a small bubble in the prefilter, it's completely normal. Now if you see foam entering the filter or the bubble seems to grow you may have an air leak somewhere, but otherwise a bubble is a normal part of life.

Thanks a bunch! I have noticed none of that so far.

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Diseasel300 · #4 07-25-2017, 12:21 AM

Since you replaced the rubber lines, you'll probably be good to go for a good while. It looks like you used new hose clamps as well which is a good idea. I got burned on my SDL reusing the original clamps and had air leaks, finally resolved by replacing the factory clamps with worm-style clamps.