Gas pressure pump

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Does anyone have a diagram of the air pressure pump on the engine of my 1918 Series 4 48 ?

I’m wondering if there is some oiling that needs to be done and how to take good care of it.

I know the adjustment on the top turns counter clockwise to increase the pressure, but in doing so

I don’t notice a difference ? I plan to double check all the fittings to plug any leakage. I would like the pump to hold about 2 pounds when driving, but right now it sees to stay at about 1 1/4 pounds.

Any help, suggestions are very much appreciated.

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Hi Richard, are you sure unscrewing the adjustment on the top of the pump is supposed to increase pressure in the tank? I looked to see if my owner’s manual mentions adjusting the air pump, but I could not find anything.

Here is a scan of the air pump in my ’19, is is or should be the same as on your ’18.

Greg

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Greg,

Thanks for the diagram. I did not have one available.

I understand that loosening # 41414 bolt allows the rod #41415 to move upward allowing the 1/4″ ball to come up further and therefore allowing more air to be pushed into the tank via fitting 34134.

I’ve been doing this with not result…..?? How do you adjust your pump ?

Rich”

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Hi Richard,

I have not adjusted the pump on my S31. I did have the common sticking check-ball problem.

I followed the suggestion from this message board to use a magnet to remove the check ball, and thoroughly clean the ball and seat. It was gummy and dirty with old thick oil. Once clean, the pressure gauge would quiver indicating the pump was pumping, immediately upon the engine being started.

I remember that my pressure usually was between 1-1/4# and 2#. It depended on engine rpm more than anything else.

You could possibly have wear on the cam or the button on the end of the piston that rides on the cam. This would result in a shorter stroke than with new parts. It appears that the intake port for air in on the underside of the cylinder. That port might have dirt partially clogging the opening? That would reduce the capacity of your pump I’d think ?

I do think that 1-1/4# is plenty to keep up with even full throttle fuel use in your 48hp DualValve engine? Or does the gauge show a drop after a long, hard climb like on Crydersville pass north east of Alturas ?? As long as the pressure does not drop, even at lower rpm under load, I think you should be good.

A hint that might make your search for leaks easier: use Windex to spray on each joint, fitting, and the soldered onto the fuel tank castings. Windex makes nice, noticeable bubbles on an air leak. A mix of Dawn, or other hand-dishwashing soap and water in a pump bottle also works well.

Do you have an illustrated parts manual for your ’18 ?

Greg Long

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Greg,

Some good thoughts. I didn’t pull the ball out, but will do that this weekend. Also checking the incoming air port

makes perfect sense. I did use a soap solution to check for leaks and did a re-gasket on the fuel guage at the tank.

I do not have a parts manual for the 18……how do I get one ?

Friend Tom with the Series 5 1919 is running parallel with us on this issue and would also love a parts manual.

Much appreciate the suggestions……….

Rich

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Richard,

Copies of the Series 4 Pierce Arrow parts book are available from the Bernie Weis (PAS) Collection at the AACA Library.

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Thanks, I’ll order one.

Rich

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Richard, I’ll bring my Series 31 parts manual reprints with me to Rohnert Park, we should be able to find a printer somewhere to make copies of the illustrations.

I’ll ask George Teebay if he has an illustrated parts manual for his ’18 48B5.

Greg Long

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