I have a nice pressure sprayer with a 5.5 Honda engine, works great, runs good, starts on first pull, bought at Sams several years ago.

It's a 2700 PSI pump, and I'd like to bump it to 3500 to 3700, reason being that it will barely push the rotary driveway cleaner that I rent from Home Depot, it will move it, but it isn't powerful enough to make it really run.

Figure the pump needs to be rebuilt or exchanged. So is it possible to order the internals for a larger PSI pump and rebuild my pump unit so it will put out more PSI, or buy a new pump, for that matter find a used pressure sprayer with a larger PSI pump where the engines failed and swap parts.

No I"m not buying a new one, I'll just keep the 2700 if I cant' convert it until the old unit gives out...

I'm not an expert but pressure takes two things. It requires a pump capable of generating that pressure and an engine capable of turning that pump. Your pump and pressure are matched with a 5.5 horsepower engine for a reason. If you look at the higher pressure units, the engines are more powerful. Water flow in gallons is also a factor. You need an overall bigger unit to do what you are tying to do. (Different engine-different pump)

My guess - and only a guess - is that, at a minimum you will need a higher pressure relief valve. I believe most pumps dump water back into the inlet side when the operator is not pulling the trigger on the wand. Perhaps this valve is adjustable by cranking down on it or perhaps it is preset. I would suspect the pump itself would support 20% more pressure before exploding. Just a guess.
Mike

You can adjust pressure all you want and it won't have as much affect as changing the pump out for a higher flow, lower pressure(Say 2500 PSI) unit. Your problem isn't pressure, it's flow... Does the rotary cleaner have a flow/pressure rating on its label?

We used to have a member here that rebuilt/repaired the pumps as his job... or at least a side job. Maybe someone knows who that is or maybe he will see this.

Those rotary driveway cleaners are great aint they? They do require a good unit to run. I have a 16 inch one used on a 13HP 4,300 PSI 4GPM washer.

What size washer are you renting, you might be better off with a smaller one if you can't up your washer output. All the rotary washers I see are rated for min / max recommended output.

Just go buy your own rotary sprayer attachment. I have a similar pressure washer and it operated this type attachment just fine.

https://www.homedepot.com/p/RY...r-RY31SC01/306343055

You'll want a wand extension too if you don't have one.

I'll come at this from a different direction because I live in a city with notoriously LOW water pressure. One likely reason your rented rotary head won't work properly may be due to LACK OF VOLUME in the water supply. If so it doesn't matter how many PSI you throw at it, if you don't have enough volume you won't have enough available horsepower at the rotary head. Now, I would suggest that you ask at Home Depot what the minimum recommended incoming water pressure required for that rotary head is but this is Home Depot after all. They stopped hiring people with the experience and brain power to know something like this 30 years ago. Ask someone at Home Depot something as pertinent as this and the answer you get will be basically DUH and you'll have to wait an hour while they chase down that "expert".

quote:

Originally posted by Gene Hillman:
I'm not an expert but pressure takes two things. It requires a pump capable of generating that pressure and an engine capable of turning that pump. Your pump and pressure are matched with a 5.5 horsepower engine for a reason. If you look at the higher pressure units, the engines are more powerful. Water flow in gallons is also a factor. You need an overall bigger unit to do what you are tying to do. (Different engine-different pump)

^^^This actually higher flow rate is more important than PSI pressure for effectiveness.

You'd need to upgrade your engine, pump, and regulator.

It would be more feasible to just sell the unit you have and put the proceeds towards a bigger unit. You'd have more money in upgrading yours than you would buying the right one in the first place.

Are you using ethanol free gas with a higher octane? That may help some.
I borrowed a pressure washer from a buddy before I had one and he used 87 octane with ethanol it seemed to run just fine.
I only use 90 octane that is ethanol free in my small engines so that is the spare gas I had one hand.
After a minute or so getting all the 87 out of the lines the thing ran noticeably smoother with quite a bit more power.
I was able to do much more area on the fence much more quickly.

The Ryobi surface cleaner linked above is what I’ll be buying this year.
I have been punishing myself doing the driveway with just the standard tip.

quote:

Originally posted by cparktd:
We used to have a member here that rebuilt/repaired the pumps as his job... or at least a side job. Maybe someone knows who that is or maybe he will see this.

That was probably me. I had a small engine shop.

What the op is asking for cant be done. The engine is not powerful enough. You need an 8 to 13 hp engine, and corresponding larger output pump, to have success with the rotary driveway cleaner. The larger units offer about 4 gallons per minute. His smaller unit probably only has 2.5 gallons per minute, not enough.

Also, you dont want more pressure. What you want is more water output. Volume of water is what actually cleans, not pressure. And to get more water output, you need a bigger engine.

And just to offer a suggestion, these Northern Tool pressure washers are a HELL of a good buy. I've recommended them and people love them.

This one has the larger 420CC 12.5HP engine that he would need to operate his rotary sprayer efficiently. On sale right now for $200 off...
https://www.northerntool.com/s..._200712420_200712420

quote:

Originally posted by smschulz:

quote:

Originally posted by Gene Hillman:
I'm not an expert but pressure takes two things. It requires a pump capable of generating that pressure and an engine capable of turning that pump. Your pump and pressure are matched with a 5.5 horsepower engine for a reason. If you look at the higher pressure units, the engines are more powerful. Water flow in gallons is also a factor. You need an overall bigger unit to do what you are tying to do. (Different engine-different pump)

^^^This actually higher flow rate is more important than PSI pressure for effectiveness.

^^ THIS ^^

There is a reason why they have you put on an approx 25 degree nozzle and keep the nozzle 8 to 12 inches away from the surface when you're using a wand to clean your driveway and that reason is that you'll damage the concrete.

When you look at surface cleaner specs, they have a rating for minimum gpm, maximum gpm, and maximum pressure. You need to size your pressure washers pump to meet BOTH of the following bullet points:

BETWEEN the min and max gpm

BELOW the max pressure.

Example:
Here is a comparison of 2800 psi pressure washers:

B&S - 1.8gpm at 2800 psi

Simpson - 2.3 gpm at 2800 psi (as a bonus it's $10 less)
When compared to the top selling selling surface cleaners at pressurewashersdirect.com:

#1 seller - neither pressure washer is appropriate since neither meets minimum gpm

#2 seller - there is a minumum 2.2 gpm and 3600 psig rating you'll see than only 1 of the 2800 psig pressure washers (the Simpson) is appropriate.

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Ego is the anesthesia that deadens the pain of stupidity

DISCLAIMER: These are the author's own personal views and do not represent the views of the author's employer.

Thanks for the input, the sprayer is a Karcher 2500 PSI 3.4 GPM unit with a 5.5 HP Honda GCV160 OVC engine.

The driveway cleaner I rent from HD is rated for a higher rated pressure washer, the reason PSI was mentioned is that is what the folks in the rental department ask me each time, "what PSI".

The 2500 unit will push the cleaner but not at the optimum speed, it moves but it's slower rotating thus it just takes a bit longer to use.

Water Pressure isn't a problem, we're on city water and have plenty of pressure from the hose to the pump.

My thoughts were to replace the existing pump with a new pump in the 3000 PSI plus range, a simple swap to get a bit more power and push the unit to a bit higher rpm for cleaning when I rent it twice a year. Since the 2500 runs it, figured a 3100 to 3400 pump would do better.

Not looking to get to 4000 psi just a slight bump up in PSI should get me there...

Tried the consumer version of the cleaner, the head unit is about half the size and it's a back bender for me, the rental size is better for my back comfort and larger cleaning area.
However I will look into it again.

I've seen pumps for sale under a hundred bucks online, which is much less than the $400 to $600 for a new unit.

And being at home locked in and looking for stuff to do this project reared its head.

The Simpson unit in the above post is 2800 at 2/4 using the same honda engine as the Karcher.

This message has been edited. Last edited by: HRK,