Hi, I have a Westerbeke 40 marine engine with a F-85 pump on it. I seem to have problems getting the pump push the water through the engine sometimes. If I am in the water it is usually ok, but when I winterize the pump out of water and feed water in thru the water filter (which is about 1 foot below the pump) it will not draw water thru the system unless I blow with air through (with impellor in place) to clear the heat exchanger of extra back pressure and then pour water into the input of the impellor to prime it. I have changed the impellor many times and the gasket is tight and the cam has been replaced. I do nor think the problem is on the output from the pump (heat exchanger, water lift muffler etc). Should the pump not be able to lift a foot or so from the water filter to the pump? Should I be able to blow through (there is resistance, but not overly) with my breath - I thought the impellor and covers etc would make it next to impossible to do this thus I thought that this non tight seal is perhaps way it is not pushing enough pressure (and water) to push out the exhaust. Any help would be appreciated. Thanks

Richard

it could be that it is wore out. large engines have a wear plate behind the impellor you replace when you rebuild it, these small pumps often do not have this.
i am not talking about the cover plate,I am talking about something you would have to remove teh cam to replace.I do not think you have one though,I am just getting to a point in a round about way,
if your pump drips water while in use ,then i would say rebuild it,but if it is not then dripping and still it is hard to make suction then maybe it is loose inside .it is not common that a dripping pump is hard to make suction ,but if i had the two problems at the same time i might think they were related.
I encounter pumps from time to time that a hard to get suction after servicing something that causes me to loose prime to the pump,But if all is well after i get suction ,and it works fine when the boat is in the water I just leave it alone