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Power washer unloader problem?

5K views 4 replies 3 participants last post by  AZBolens800 
#1 ·
I bought a Simpson S2700H power washer with Honda GCV 160 engine for $20 at a garage sale. The seller said that it would stall out and they didn't have time to mess with it.

The engine starts and runs fine without the hose and gun attached. The pressure seems fine. With the engine off and the gun and hose attached, the water stream is fine. There are no apparent clogs in the gun or hose. When the engine is then started, it will run for 1-2 minutes, spray well, and then stall out. After this happens, it can't be pull started. The engine won't turn over because there is too much pressure built up in the pump/hose. If the trigger is pulled, a blast of water will shoot out. This relieves the pressure and the engine can then be pull started.

From what I have learned, the problem is that the unloader is constantly open, ie. not going into bypass when needed. So I removed the unloader valve and inspected it. It was not frozen, which I think usually leads to a constant bypass mode. The little shaft moves easily in and out without much force applied to it. The tiny holes between the o-rings do not appear clogged. I made a video of it here:

Anybody know how this unloader valve works? I assume water goes into those tiny holes and a pressure gradient must cause the shaft to move in or out.
Can I fix it or do I need to buy a new one?
 
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#2 ·
Right now where I work we are selling a pump that fits GCv160 for 80$. Most of the small homeowner grade pumps corrode badly when stored, meaning even if you do fix the unloader something else is bound to fail.
 
#5 ·
If you you have a pneumatic hammer/chisel just beat/smash the old pump off, being careful not to damage crankshaft, if you don't have one then try lots of penetrating oil on the crankshaft. Even if you replace the unloader you will likely have problems with the valves and seals- all these parts do not like sitting for a long time with water on them. It is an AR pump made in china, not great quality, but I do not know of any "good" vertical shaft pumps- all industrial/commercial pumps are horizontal.
 
#4 ·
I believe I had the same PW (Excell). Same engine and pump was all aluminum. Had exact problem you describe. Un-loader looked identical too, I tried adjusting (mine had screw in end). After much tinkering and a blown hose (Weird setup off bottom of pump), while adjusting to high. I removed damaged hose which must have been a safety of sorts, then installed a pipe plug (same size as hose fitting). Lowered-backed out-un-loader, started machine with trigger pulled as you describe. I adjusted pressure slowly while releasing trigger to ensure it unloaded. I raised to what I thought was good pressure. It unloaded without issue for the remaining time I owned it. I sold to a friend explaining what I did and he still runs it today without issue to my knowledge. I have no good explanation why it worked well after replacing that hose with a plug but it did. Probably not the safest fix but it worked.
I've since bought a rigid unit with an oil lubricated pump, it is a much nicer unit than the old one.

I'd buy the replacement pump and hopefully you can get old one off. Not sure if shaft will accept new one?

Good Luck,
MU
 
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