3.5GPM/3000 Hot Water PW To start out?

Rookie Looking for some advice! (Shocking right?) :slight_smile:

I own a mobile diesel repair business. All we work on is AG equipment and Semi Trucks. Some of my customers have asked me to start offering mobile fleet washing because our attention to detail Is impeccable and we genuinely care about their equipment.

I already own a mi-t-m pressure washer Hsp-3004-3mgh , it’s specd out at 3.5GPM and 3000PSI with a 100 Gallon Water Tank and misc hoses and wands because we use it to wash of the engines and parts we work on. I paid $500 for all of it from an old customer and it all works as it should. So I don’t want to buy a new unit until I make sure there is enough margin in this to justify the expense.

I have read on here that a better setup would be to slap a 5.5gpm gear drive pump on this gx390 and it will allow me to be more efficient and it seems like for my application (fleet washing only) I should focus more on gpm than psi.

Do you guys think I can run this setup with the 3.5gpm pump until it ■■■■■ the bed? And then upgrade. Or do you think I should spend the roughly 1k and upgrade the pump now. How much time will it save me per wash roughly having the 5.5 vs the 3.5 for a touch less 2 step wash?

I’m usually a numbers guy and will look at profit per job vs cost of new pump and can see what my break even number would be to pay for the pump upgrade, my issue is that I know engines, not washing trucks, so I have ALOT TO LEARN about profit margins on this side of the industry before formulating a business plan and planning for asset purchases…

Thanks in advance for your help.

Im still kind of a newbie, but ive done fleet washing for another guy.

I think 4 gpm is great, If your doing fleets you also got to think about water reclamation.

3.5/4, not that huge of a difference but its there, you just need a good 2 stage wash system with some good chemicals, and figure out if your brushing or doing touchless, you say touchless but figure out if your chemicals really give you quality.

8 gpm is awesome but ive only used it on the worlds largest pieces of heavy equipment, d8 cat etc…

If I were you use your machine until it junks or look for a used pressure washer, 4000 psi at 4 gpm (4/4) USED with a GX390 and CAT pump, belt drive preferably, and run a bypass line.

Hot water is best for fleets if you are really talking $$$.

If i was in your shoes i would buy a used CAT pump machine for less than $700 or go buy a brand new Graco 4/4 with a CAT, they are belt drive at $1800-2 , would last you a LONG time with good care, save up for hot water if you want to grow.

Not advocating for either side here but Russ at southside can get you a 5.5 gear for just over $800

I appreciate the referral!

Other than promoting the product itself, what are your thoughts on my situation? I knew how much the pump is, I need to know what my beat play is here to balance efficiency ca initial spend.

Thank you for the advice router! Luckily this machine is a hot water machine. You mentioned a CAT pump. Are they direct drive or gear drive? I already have a gx390 motor on this and the heating coil system is rated for 6gpm (it was upgraded by the previous owner) . Thoughts on just upgrading the pump on mine? It seems to have all the specs you listed in the others, except for the pump itself.

Just use the 3.5 until it goes, then get a 4, you probably have a AR so it should last a while.

I think its hard to run a 6/8 with a gx390 but I could be wrong.

Get a cat when you are serious, it will last you probably 10 years if you take care of it.

Local car wash has had CAT 310’s since 05 and serviced them once a year at best, they still work.

I haven’t the faintest clue about fleet washing, would think you’d want to wait to upgrade till you know you like it and have some decent business coming In

Ok I appreciate the advice! Ill just run it till she blows!

Ok I appreciate your honesty, I’ll keep digging into my specific situation. Thanks!

For clarification, and simplification. I’m mainly looking to see if 3.5 GPM will be sufficient or if a 5.5 gpm pump will significantly Increase my productivity? I understand that on paper the 5.5 gpm pump flows roughly 36% more water assuming it is fed a constant supply of water, but what I’m wondering is if the motor will actually support the 5.5 gpm consistently and if the flow increase has a linear effect on productivity? I.E. 36% better flow equates to a 36% increase in productivity? Usually that’s not the case. Im guessing if the pump flows 36% better I may only see a 10% increase in my actual working productivity.

Wait until the actual fleet washers can post.


Give the calculator a chance to cool down son, your way overthinking it. Productivity in percentages doesn’t mean anything till you have a baseline of knowing what your doing.

Well that’s my big hurdle, like I said, I’m a numbers nerd. I can account for learning curve or my employees, and training, and all that. But I’m trying to figure out if it’s worth the investment of time to dive into this. Right now I make about 14k per month per employee working on trucks, much higher risk, much higher reward situation for sure. But if I can keep my customers happy and still turn 6-7k per month on a lower paid guy or 2 with less exposure and keep my customers happy, I’ll suck it up and do it. I have about 300 pieces of equipment between 5 customers that they want me to wash and maintain bi weekly.

You need to see results, theres always dirter stuff, stuff that requires more chem, equipment failures or bind ups and un forseen circumstances.

You also might need a dedicated “wash guy” who really knows what he is doing, make sure hes detailed and understands where dirt gets built up on these things.

Are you cleaning tracked pieces of equipment? Excavators with large arms?

No we will mostly be cleaning semi trucks with tank trailers.

I’m sure there will be the occasional bailer or swather though. Any advice for me on washing equipment?

I would just stick to your 3.5 gpm. Someone above mentioned a gear drive but we don’t even know if your hot water machine can use a gear drive pump. Most are belt drive so they can turn the fuel pump, blower, or generator.

It sounds like you’re going to be hauling your own water. That’s another reason why I’d stick to the 3.5 gpm for now. It’ll be easier to manage water consumption with a 3.5 gpm. An 8 gpm is probably just way too much when hauling water. You’ll empty the tank in 10 minutes. I agree with @router. Use your 3.5 gpm to make sure you’re going to stick to fleet washing. Once it blows then upgrade to a 4 gpm or maybe a 5.5 gpm. You’re GX390 can run a 5.5 gpm but you’re only going to see about 2500 psi max. A little less once you figure in pressure loss from length of hose, fittings, etc.

You need @Hotshot to chime in. He knows his stuff when it comes to fleets.

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Heck yeah man thanks for the advice!

Productivity decreases after 4.75 gpm and 1900 psi. Anything less and you can’t wash effectively. I see one of two things happening with your new venture. You get them really clean with two clowns at the helm tearing stuff up, taking forever and a day to clean just a few pieces. Or your guys deliver less than stellar results because they lack the experience to clean well at a lightening pace. Either way you’re playing high stakes poker with your bread and butter. Just food for thought before you think truck washing is simple. I’ve seen guys take up to two years before they could float through work. Four minutes too long on all the trucks with a sizeable fleet is a additional 8 hours in labor between two newbs and that’s everyday. You’re going to be shocked at the man hours it takes to get a sizeable fleet “brought up” by newbs.


It really is detailed work, and it takes time, knowing how to flush stuff out real good, the right amount of detail to use.

Usually your run of the mill guy is not going to be constantly thinking about efficiency, that point A to B movement, and producing results, he just wants to milk your clock and get paid.

Maybe think about paying your guys commission if you can, may make them more money as well as you.

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@dperez That’s really good insight. I guess I lack the understanding of the possible learning curve I will have to face with this side of the industry, and that mixed with an insufficient tool Arsenal could tank the new venture quickly.

From my limited but focused research on swapping pumps, the engine on my pressure washer (GX390) would run a 5.5 gpm gear pump at about 2000-2100 PSI on 150’ of hose.
And I’ll need a buffer tank. Is my math incorrect? Am I trying to make gold out of lead here?

Also my heater on that unit was swapped out with one that will allow a 140* heat rise from ambient temp up to 6gpm. So I’m hoping that won’t pose an issue if I increase the flow rate of the pump.

I won’t have employees running the fleet wash side until I can do it myself successfully. I’ll probably hire a lackey to help me with some of the work, but I’m a firm believer in learning ways to properly perform a job with A quality outcome before turning people loose on it, I have to be able to effectively manage the employees and I agree with you, without first hand knowledge to teach them, It’s a disaster waiting to happen.

I’m not going to run out and sign all of my accounts on fleet washing, I dont really need to be greedy here, my main diesel business has a steady positive cash flow that supports us just fine, this is more of an expansion to the business that can take as long as it needs to.

My main goal here is to get into the industry at a decently low investment cost if possible, Use my customers trucks to learn on and practice techniques, and then formulate a more educated hypothesis on potential income and long term sustainability of this portion of the industry in my specific region. Basically I want hands on market research. That’s why I’m trying to avoid spending more than 2500 in equipment right now until I can decide if it will be a long term endeavor for me. Sorry for the long winded response.

If you were me, and assuming I’m bound and determined to make this venture work. What would be your approach on my equipment situation?