My fuel primer pump seems to be sucking air. I don't see any bubbles in the feed line but it blows bubbles into the filter housing. Could be the o rings, I'll double check that but I'm thinking the pump is leaking.
Anyone have any ideas for a replacement? The later (post '76) ones that go on the IP won't work. What else would fit in there or at least get the job done?

I have a couple of good used spare Pierburg primer pumps in storage.
Send me a PM if you end up needing a replacement.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

If you examine your primer pump and there is a way to seal it by stretching a balloon over it. As there was in the earlier original 123 type primer pumps. Just reduce the contained air in the balloon if any it should stop admitting more air being sucked into the primer pump.


If the neck of the balloon is tight around the pump barrel. Temporary repair or verification the pump is sucking air in there.


Nobody can call me cheap. I use new balloons.

Good idea. I was also thinking that I could seal the intake and the output and draw a vacuum on it and see if it will suck air that way.
And yeah, nice to know these are still available. I'll let you know how this one tests as soon as I figure out a test.