Originally Posted by Trekker
Thank you for your prompt reply and information. I turned off the City water supply, and, as you described, the fresh water tank is showing full. So can you tell me what part is malfunctioning and needs to be replaced? You mentioned the water pump and a check valve. Which part is malfunctioning? And where can I find the water pump? Is there a way to reset the check valve, if it is leaking? Thanks so much for your help.
I've never seen a 337 however I'm betting its close to being similar to my 378. The pump is normally under or close to the FW tank. Mine is in a basement compartment, but hidden behind thin black sheathing on the curb side of the unit. Easily located by opening comartment door in the area of the rear tires. Have someone start and stop the pump while you listen and you'll soon find it. If fitted the sheathing comes down easily with the square head screws and carefully work the sheathing out.
Once you locate the pump, you'll see on the "discharge" the pump casing will end into another device (cylinder with fittings on both ends maybe two inches or less long. Discharge side usually connects to hard blue piping, suction conect to tank via soft reinforced hose. Its simply a ball or flap type valve that allows flow in one direction. Of late many pumps come with the non return or check valve as an integral part.
If you are ready to repair or replace, make sure water system is drained and tank is either drained or has valve to isolate. Pump water fittings are hand tighned nuts and usually has four foundation bolts. There are tons of mfgs and model combinations, can't tell you exactly how to disassemble your pump but you goal is to clean by flush or mechanically the non-return check valve. Its easy to test when ready by attaching to hose bib or just gravite water into the pump to see if holds. If necessary sometimes can be repaired due to internal damage, I doubt thats the case here.
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