Put a new pre-filter and main filter on my 83' 300TD today. Had no problem priming the system and didn't even need to loosen the metal injector bolts, only the bolt on the top of the main filter housing. Started easily and ran smooth, never died.

Anyway, now that I finally have a new pre-filter (the old one was burned from engine heat and dirt and you couldn't see inside) I can see a big old air bubble in there I can't seem to get out. Is this normal or might I have a leak in my hose before the pre-filter?

Big bubble is normal. Bubbles flowing through the prefilter is NOT normal.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

They're not flowing through, one little bubble up towards where it exits which i can usually get out, one big bubble and then every once and while a very very small bubble where fuel is coming in but it could also be the big bubble breaking up from vibrations. Sounds like everything is A-OK, thanks.

Yes.