Recirculate water thru cooling tank

Hey guys, after thirty years of law enforcement, I retired, and thought I would start, a small pressure washing business, to supplement my retirement. I have been watching from the sidelines for awhile and have learned a lot. I have a trailer (5’ X 10’ Single Axle) with a GX390 DD, with a AAA triplex pump Model # EW4040 4 GPM, mounted on a skid plate with a 50 gallon buffer tank, plumbed 3/4" through a North Star 5.5 GPM On demand pump(Booster). My question: The AAA EW4040 pump has the downloader valve incorporated into the manifold of the pump, I need to circulate water through the buffer tank, to cool the pump, can I purchase an external downloader and cap off the old one, to accomplish this task. Note: Also considering getting away for the DD, and go to a belt or gear box, that would get me up to at least 5.5 GPM , with an ultimate goal, of 8 GPM what I have wears out, any advise you can offer would be appreciated.

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I’d just feed from hose if u have a direct drive 4/4, too much trouble/things that could go wrong with a buffer… When I had the 4/4 I just set the unloader to run on the ground when off the trigger

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Thank you so much for your reply, not sure how to set the unloader to run on the ground, when it is integrated with the pump?


Seriously, you can get an ‘external’ unloader that’s fully plumbed and route bypass to a small 30 gallon buffer tank. Let the other guys chime in though, I sold my 4/4 a while back.

The easy part is routing the unloader to the tank, the hard part is getting a direct drive to pull water, no point when u can just easily hook the pump up to the homeowners spicket

@Pw2020 can you post a pic of the pump and the unloader it has?

This is all bad advice


Got any magical way to make a direct drive pull water? I find hooking to a hose a lot more reliable than having a 12v pump to feed your direct drive

A DD 4/4 isn’t a machine anyone in business needs to be using. Don’t bypass water on the ground. A buffer tank is never a bad idea.

You are right. However as someone who recently used a 4/4 direct for over a year, from my experience a buffer tank is way too much hassle and the benifits you would get with it would be the same as routing the unloader to dump on the ground…

You may not get enough flow on 1/100 houses but hopefully by then you will be on to a better machine

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Sorry guys been on the road, last few hours, and have read your reply’s. I am impressed you guys jumped on this like a duck on a June Bug. Your responses are right on, and yes where I am is not where I want to be, and you guys have made that even more clear, let me explain. I purchased a 4200 PSI, with 4 GPM, and picked up few driveways and sidewalks etc. , in a residential area North of Houston using house water, I found that 6 out of 10, (60%) didn’t produce sufficient gpm, and starved the pump. I learned that the devise “An Anti Siphon back-flow preventer” prevented the water from going back into the house. Back to the drawing board, installed a 50 Gallon, tank with a Hudson float valve, to make available and hold whatever the house water would produce, and plumbed it out of the bottom of the tank, to a 5562Q North Star 12Volt (On Demand) Sprayer Pump, rated at 5.5 GPM (tested out at almost 6). Like I said not where I want to be but where I am.
Note: Sending the requested pictures

I speak from experience, a direct drive 4/4 will indeed feed from a buffer tank provided the water level is much higher than the pump. Mine sounded a bit weird doing so, but it got me through enough jobs so I could upgrade to a belt drive.

Like you I also experimented with a pump but it was 110v and a pain trying to plug it in from the street.

You gotta be kidding me! A disposable pump feeding another disposable pump, you’ve ruined my evening.


Don’t do that, customers don’t like seeing you dump there water on the ground or out in the street.

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I didn’t say it would be pretty…

Regardless. That pump has a built in unloader, not way for it to recirculate water to a buffer unless you add another external u loader.

Having the pump draw water from the tank is possible. That’s how I started out and it worked fine.

I would gut that unloader and mount a real unloader on that pump manifold… Ive seen other guys do it here and then you can by pass to the tank

Hey guys I appreciate all of our responses, it is so good to have you guys to bump thing off, and learn a lot about, all the mistakes one makes when he is flying by the seat of his pants. For now, I think I will get and install an exterior unloader valve, plumbed and ready to go (can someone recommend where and brand). In the not too distant future, I would like to correct some of the mistakes, that I made in the beginning. Looks, like I’m gonna have to stay with the Honda GX390, for now but am considering going to a belt drive and upgrading the pump (not a disposable) to a 5.5 GPM (or whatever 13 HP will handle) . I value your input, and totally respect knowledge, if anyone has another path to offer, I am all ears.

I have a gear driven 5.5GPM 2500 PSI pump on my GX390. 4 bolts to add it.

Gear drive is the bomb:+1:

Thank You, sounds like the best way forward, for now. Quick question: how well would a surface cleaner work with 2500 divided by 2 (nozzles) = 1250 ea.