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Vince I worked in the pump industry (pumping liquids) for many years. And, I am familiar with air pumps on Cadillacs and other cars that use air to pressurize fuel or for starting the car. But I have not seen an air pump on a Buick. Can you post a couple of photos?

I suspect that if you sleeved the pump case, and dressed the pump vanes to seal against the new sleeve, oil must be coming from the shaft seal.

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Mark, Thank you for responding. I think you are correct but I do not know of any way of correcting it. On the Buick B55 6 cyl. the pump in mounted horizontal and the intake is taken from within the engine thru the grooves on the pump piston. The port on the outside housing faces downwards which does not help either, the pump body housing cannot be turned so as to bring the exhaust port upright because it has an offset mounting in relation to the camshaft. I did find that when I adjusted the psi down to a pound and a half It pumped much less oil into the fuel tank. I may just have to live with the oil loss and oily gas. I wonder if anyone else with an early Buick has had this problem? I am one who likes to keep things as original as possible.


Vincent Bakich


1914 Buick B55

1919 Locomobile Sportif

1921 H.C.S. Touring

1921 Marmon Speedster

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Ok, so from your last post it seems you have a reciprocating air pump that runs off of a lobe on the camshaft. If the air intake comes from a slot in one side of the piston (I wish I could see a photo or drawing of it). It is possible that the piston is installed up-side-down. If the slot is at the low side of the piston it would draw in more oil.

In any case, you could make a small separation tank and install it somewhere in the pressurized line between the pump and the fuel tank. If you connect the input line near the bottom and outlet from the top, it would allow any oil to drop to the bottom where you could have a drain valve to preiodically remove the excess oil. Better yet; there are in-line air/water separators available from most automotive paint suppliers that would probably work well for this.

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