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Oil in vacuum pump


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Well as part of the engine work I removed the fuel pump to improve access. While it is off I decided to see what I could do about the vac side, which has not been working well since I o'hauled the pump last summer (fuel side works great). So I opened up the top and I found a whole lotta oil! (pic attached). The vac diaphragm looked good, no oil on the bottom side, in the bottom chamber, or on the oil seal - all dry. Just in the top section and some on the top side of the vac diaphragm. Any ideas?

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Cheers, Dave

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I will preface this post by stating that I don't know anything about a '40. In my 55 Buick manual it states that the vacuum pump is a dual action pump which operates on both strokes and that one chamber "exhausts" into the intake manifold and the other chamber exhausts to the crankcase. Is it possible that your vacuum lines have been crossed? It pulls air in from wipers and pumps it into intake and crankcase. John

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Mark: The only thing I can think of is the last owner dumped a bunch of oil into the wiper motor to try to get it to work and when I hooked it up after the overhaul I sucked it all into the pump. Once I realized that the wiper motor was shot and leaking air I just capped off the line there. (I have since had the motor o'hauled and it is ready to go.)

John: Yep, lines are hooked up proper. And I do remember those vac modulators leaking trans oil into the manifolds!

Cheers, Dave

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I have to agree about too much oil in the wiper motor...

I had that same experience with my '34 many years ago, shortly after I got it - but my fault when I reversed the hoses (duh!).

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