Recommendations for an unloader? Hooking up 2 washers

Howdy ya’ll. Been lurking for while but now I figure I should ask a question since I want to upgrade my machine. Right now I’m running a 4gpm pump but I was going to order a siamese twin kit and some unloaders from Russ Johnson, to install on a gx 270 and a 3.5 gpm pump for total of ~7gpm at 3000 psi. I’m assuming he knows what a good unloader is, but before I purchase I was wondering if anyone has any recommendations, or if there’s a less expsensive way to hook 2 machines up. I don’t want to get rid of what I have because the cost of a 22hp engine alone for an 8gpm would be more than getting another gx270 and a 3.5gpm pump.

Anyone have any experience running two pumps together? Russ says it should be fine as long as A: they have the same PSI and B: aren’t using an EZ valve unloader. Should also mention that it needs to be a pressure trap unloader and not an EZ one (I tried looking into the difference between them but couldn’t find much, an explanation would be greatly appreciated!)

I don’t know too much about unloaders so I really appreciate y’alls help. Thank you so much and I did try the search function but I think this topic just doesn’t come up much… or maybe I’m blind. I’ve only been doing resi so it’s not the biggest deal to have 4gpm but I do a lot of driveways so having more flow would be ideal.

Edit: Also the search tells me that a 50 gallon tank should be enough of a buffer. Would that be enough in youre experience? It only needs to be a buffer I never need to run off well water in this city. I could always grab 2 barrels if needed, there’s a guy on craigslist givin them away for free!

much easier and safer to buy a 7gpm machine


Would like to but as I said it’s out of my budget.

How much is another GX270 and 3.5 gpm pump?

I have no problem with a used engine, can find them for about $250 and then my budget for the pump is about $350, I’ll spend up to $400 on good pump but would rather less, that should be enough for a decent 3.5 gpm. Then another $100 for the fittings and what not. In total it would be less than $1000, which I know you can’t build a 7gpm for that much.

This is a different conversation, but if you’re scraping by to buy a small pump and small engines you may not be charging enough or your money would be better spent on marketing.

Search Predator engine. If you really want a big machine on the cheap you can build an 8 gpm for around $1600.

Was thinking of that, I could probably get about $400 for my old machine. I’ve only done residential for a year so yes start out I made barely any money at first. But I’ve gone from charging $50 for a driveway (yeah seriously) to $175 for the same work so progress is good, started out in summer last year so I was kind of setting up. You want to know honestly? I started with a 2gpm machine I shoved into my trunk and then I saved up for a 5x8 trailer and 4gpm machine.

I run two 4.5 GPM machines hooked together all the time without problems but I have everything exactly the same. Same engines, same pumps, same un-loaders, same hose reels, same swivels, same hoses, same guns, same nozzles. But, I agree with IB that you would be better to take that money you have and wait to invest in better equipment than throwing it into a sort-of upgrade. You’ll only have 7 GPM (at best) but have twice the fuel costs, twice the maintenance and twice the opportunity for a mechanical failure. Save up and get an 8 GPM when you can afford it.

I run two 4.5s because I have two employees and find it faster to have one doing the concrete and one doing the house wash or both doing the house wash, or one doing the house wash and one doing the windows. I would love to have a 8 GPM and a 4.5 or 2 eights, but the water flow here is terrible and there is no way I could efficiently run 12-16 GPM without stopping every 30 minutes.

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Maintenance doesn’t really double though. A Honda gx630 & 690 use double the amount of gas since it still has 2 cylinders. Uses twice as much oil plus has a filter vs the smaller engines. Whats the chance of both engines going out at the same time. These are mechanical engines with very little to break, the most common problem is probably the carb. To me the biggest advantage of having two machines is that if one breaks i can keep on working. Ive had that happen too, i would hate to have one machine on the truck and it fail, now im having to tell the customer i cant do the job.

Plus If you take two 5.5 machines and hook them together your at 11 gpm for about the same cost of one 8gpm machine, plus as you stated you can now having one guy on the flat work and the other one on the house.

It does double. When I service the equipment, I have 2 engine oil changes, 2 pump oil changes, 2 spark plugs, and 2 air filters.

I agree having two machines is great but when you are only adding a 3.5 as he’s asking about, I wouldn’t do it. I think he should keep his 4 GPM and then buy an 8 or at least a 5.5 GPM, in other words add a bigger machine to the set-up not a smaller one.

When it just me on a job, and i have a decent amount of flat work i hook up my 4gpm and 5.5 machine together.

Because of the different psi ratings the psi hitting the surface drops to the lowest of my two machines (2500psi), but thats all i need for flat work. Also both of my machines have ez start feature and still work fine. Hooking them together puts more stress on unloader, so i dont hook them together often.

In terms of the time to do the maintenance it could double, but the amount of oil is the same. A gx390 holds 1qt, a gx690 use 2qt so same cost. The smaller engines dont have a oil filter, so i would chalk that cost up with having to buy a 2nd air filter for one more machine. Running two gx390 means 2 spark plugs, and one gx690 is 2 spark plugs. The only thing it really adds is having one more pump, so another $20 in pump oil. If all the belts where to fail, the gx690 normally use 3 belts while the gx390 use 2. So one more belt you have to buy. The biggest draw back i can think of is the space to now have too big machine taking up floor space vs one, and not being able to run a remote fuel tank for the gx390 (i know there are ways to do this).

I agree with buying a bigger machine, just like to give everyone else reading another idea.

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I think we are talking about two different things. I was comparing one 8 GPM machine to having two 4 GPM machines. If I was a solo guy, I’d just wait until I could buy an 8GPM and keep the 4 as a back up which is what I was trying to tell the OP. However it’s Friday night and my brain has too many tabs open…