Is that relevant? If those filters tend to keep an air bubble in them, and you are pushing return fuel ipunder pressure into there, no doubt it will bubble up. Ever look at the diesel in the filler neck when you fill the tank?

I’d be more interested in getting some new hard lines that you can see through clearly and observe them.

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Current Diesels:
1981 240D (73K)
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Past Diesels:
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