Hammer gets my power washer working, help.

I have a Dewalt 3800 power washer with a Cat 67DX39611 pump. This unit gets infrequent use for my business. Normally when I connect the water hose and turn the water on and pull the trigger water comes out the nozzle. Today it did not. When started no water came out. Some gentle hammering on the pump, nothing. After some tinkering I thought it might be the inlet check valves sticking. With the water hose connected I clamped the garden hose tight and then struck the garden hose with a hammer between the clamp and the pressure washer. The pressure pulse must have freed the check valve (valves?), and I got the washer working. Tonight after reading the manual I learned that the there is a special fluid DeWalt DP80 (or RV antifreeze) I should be working into the pump when it sits for more then a month.
What if anything do you do when your pressure washer sits for a while?
Thanks for any help!
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On Mon, 31 Oct 2011 17:18:56 -0700 (PDT), andyeverett

If it stays outdoors in an unheated building, you MUST drain it or freezing water can ruin it. I always pump mine dry, then prop it up so any remaining water can drain out. I also have a small portable one, that one just comes indoors in cold weather.
Pouring a little mineral or vegetable oil in the inlet cant hurt either.
RV antifreeze is cheap, but how do you get it in the whole unit?
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On Nov 1, 12:52 am, snipped-for-privacy@myplace.com wrote:

Dis-connect hose from the hose bib and drain all water out of hose. Hook hose to pressure washer. Pour the RV antifreeze into the hose. Run the pump. When the pink fluid comes out the other end, you're done.
Hank
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