I’ve got a new Simpson 4 gal 4200 psi that has been used consistently throughout the past month over 18 hours. However, whenever I use the gun it delivers pressure for a few seconds then makes a loud shaking groveling sound where it fails to deliver pressure. If I hold the trigger it repeats this behavior.
Another thing to note: the unloader/pressure regulator lock nut is cracked where there used to be a set screw (I’ve never touched the unloader except for a quarter turn and back). I don’t believe that is the issue because the pump has been doing this before it cracked, but I’m just guessing.
It comes with a chemical injector where I use bleach and my main concern is if the issue is due to bleach trickling back into the pump after a post treatment and destroying the rings.
I’ve checked the oil and it is just above the red dot on the gauge. I’ve never ran it without water and or air in the lines except on one occasion for 20 seconds.
Sounds like you have an air leak somewhere in the system (your dsi is blowing water, you said the unloader has an crack, it could be your gasket on the carb, it might be the pump packing, or it could be insufficient water flow from the spigot) once enough air gets into the system it drops pressure because of the change in the load.
Bad news is I don’t think those pumps have serviceable unloaders, good news is I believe it has a gx390 and you can use this as an opportunity to upgrade your pump.
That shaking groveling sound happened to me when we had debris blocking the flow of water at one point. It was a big bug lol. That was when we only had a screen after supply hose.
The pump has little piston windows where you can see the 3 pistons inside the pump. There were SH deposits there probably when I spilled a little SH when I unplug the SH supply and it dribbles on the pump a little. Maybe it got through those holes and messed up some O rings…
The CAT brand is okay… there are better and worse brands.
However it is still a direct drive pump and if it’s fried (you have to keep pulling the trigger every couple of seconds, not minutes, or the water cycling will overheat the pump, which now that we know that is likely the cause) figure out what’s wrong with it (aka tear it apart) and see what it needs… for that pump new packing’s are like $75, new unloader block is $150, a complete pump is $550… at that point you need to figure if spending the money to fix it and hopefully last longer then this time is worth it or not. Personally I would use it as an opportunity to upgrade to a gear or belt drive pump.
I ran it again today with a different water supply, and it ended up spilling oil through the oil filler cap…
Before this I ended up unscrewing the unloader to check for damaged O rings and reassembled it and tightened it, not sure if over tightening could have resulted in it or just the pump is kaput.
I’m not looking to upgrade I just need it working since I only have this summer left to pressure wash because I’m in school. At this rate I need it fixed as fast as possible. Wonder if I can use the warranty but I think that will take a while.
Sounds like that puppy is kaput… unscrewing the unloader shouldn’t have any impact on oil leaking, the two chambers are separate.
The options I see:
move forward with the warranty… it could take longer, but if covered it would be the cheapest route
pull apart the pump packings and see if those are worn… if you’re mechanically inclined this could be cheaper and easier to do, but there is no guarantee that it solves the problem… might be a temporary fix to a least get you through the summer, but could also void any future warranty claims
buy a new direct drive 4/4000 pump… most expensive option but quickest, but now you’re stuck with a cheap direct drive pump
Without tearing it apart there really is no knowing what it all needs. Depending on where and when you bought it, they might just swap it out in store.
Fastest option: replacement. Whether it’s a whole new washer or just a new pump. But it’s part of the cost of doing business. The transmission in a truck will eventually fail, but it’ll fail prematurely when abused/misused. The same thing has happened here to your washer’s pump.
Look up the model/serial number of your machine and pump and just order a new pump. You don’t have to go back with a Cat pump. There’s plenty of 4/4 machines with AAA pumps. The bolt pattern for the GX390’s will be the same, but just verify what crankshaft type you have if you are thinking of a pump other than the original replacement.
