I have a 1600-ish psi pressure washer pump. The 3.5 hp chinesium gas motor on it is awful. Someone bought it years ago and started using it without putting the oil in it. I got it vaguely running with some 90wt oil enough to test that the pump works, but the engine is toast... so they donated it to me.
I have a few electric motors around the shop and I do want an electric pressure washer in the new paint room, and 1600 psi is more than enough for washing down paint bins, cleaning the floor, etc.
So, good pump + plenty of 1/2" shaft electric motors + whatever else I need = electric pressure washer... right?
I suppose I need to maintain the mechanical spring regulator valve but how do I control the motor? I have played with electric washers before, but I never understood the magic electrical boxes or where they reference pressure.
Can y'all point me in the right direction?
Maybe a flow sensor on the low-pressure side?
What hp electric will I need for this little 1600 psi pump?
I looked through all of my motors and none of them seem appropriate. The one that would physically work (correct shaft with a woodruff key) is 220v-only and it's so old it has a cast iron case and bearings with the little oil wick.
My GC190 motor on my 2900psi makes about 4.5-5.0hp at 4000 rpm I believe so your going to need something in the .7-1.2hp range I would imagine at a similar RPM depending on head design.
Yeah, aren't the gas motors governed to like 3600 rpm? Should be able to find an electric motor with that same max speed and just plug it in. (1800 and 3600 rpm are the really common ac motor speeds because of 60hz ac power).
Also, I really want to do the same thing with my wood chipper, so I'm following along closely.
They exist, but 3600 rpm motors are not as easy to find as 1800 rpm motors. Prolly need at least a horsepower or two.
Beware getting water on "open" type motors. Prolly won't end well.
Take video. Post here. Be a hero. 
1988RedT2 said:
They exist, but 3600 rpm motors are not as easy to find as 1800 rpm motors. Prolly need at least a horsepower or two.
Beware getting water on "open" type motors. Prolly won't end well.
Take video. Post here. Be a hero.
My thought was to mount this thing on a shelf that is about 6' up, and I can put some kind of cover on it. It won't be waterproof, but it will be well out of 99% of the moisture.
I think the gas motor on it was rated at 3-3.5 hp, but that is likely way overkill. From the sounds of it (while it ran) it was likely a 3600 rpm or so. Certainly more than 1800.
Will I neuter the pump if I do an 1800 rpm motor?
wearymicrobe said:
My GC190 motor on my 2900psi makes about 4.5-5.0hp at 4000 rpm I believe so your going to need something in the .7-1.2hp range I would imagine at a similar RPM depending on head design.
It's a typical axial pump like most cheap washers have. I'll try to scour the webz to find its RPM capability, but I know I shouldn't be limited by top RPM, just concerned that I might give it inadequate RPM.
You can buy an electric pressure washer new for $100 - $150, with all the attachments and ready to go. You maybe able to find used ones for much less. The question is how much is your time worth for converting the one you have.
1600 psi and 1 gpm is going to require something very different than 1600 psi and 4 gpm... Something to consider.
How much water is as if not more important than the pressure when determining how much power you need.
stuart in mn said:
You can buy an electric pressure washer new for $100 - $150, with all the attachments and ready to go. You maybe able to find used ones for much less. The question is how much is your time worth for converting the one you have.
I've owned two of those $150 electric pressure washers. They lasted about two car washes. Cheap pressure washers have a lifespan that can be measured with an egg timer. I can build this one for more or less free.
The pump I have isn't anything special, but I have rebuilt several. I can also buy good piston pumps for $80, so even if this one goes belly up, an $80 pump and a free motor for a good wall-mount washer doesn't seem crazy.
ronholm said:
1600 psi and 1 gpm is going to require something very different than 1600 psi and 4 gpm... Something to consider.
How much water is as if not more important than the pressure when determining how much power you need.
Truth. It's one of the reasons I thought I'd use this pump. Lower pressure, but it will do up to 2.3 gpm (if I believe the chinese translation on the website)
Curtis said:
Will I neuter the pump if I do an 1800 rpm motor?
Yeah, I would think that if the pump was running at approximately half of the design speed, both pressure and flow would be greatly reduced.
I think I might have to give up on this idea. I have found several motors for cheap or free, but I haven't been able to find any in the right configuration. I re-measured the hole in the pump and it takes a 1/2" shaft, but about the time you get to 3/4 hp and up they are all 5/8" or 3/4" shafts.
Might have to pony up for the right components. A good commercial electric 1500 psi/2.5gpm unit is nearly $1000, but I can do better than that.
Are you stuck using electric? If not I would consider a motor from harbor freight. Slap that thing on and go. You could get fancy and convert it to propane.
Curtis said:
I've owned two of those $150 electric pressure washers. They lasted about two car washes. Cheap pressure washers have a lifespan that can be measured with an egg timer. I can build this one for more or less free.
I guess I've had better luck...my Karcher electric is probably 10 or 15 years old and it still works fine.
dean1484 said:
Are you stuck using electric? If not I would consider a motor from harbor freight. Slap that thing on and go. You could get fancy and convert it to propane.
Yes, stuck with electric. If it weren't inside in my shop's wash bay, I could have just bought some rod and main bearings for the trashed gas motor and done it that way, but the enclosed room means I could use the gas engine until I passed out with a headache, or until the code enforcer comes by for her yearly visit and cites me for an IC engine in an enclosed commercial space.
stuart in mn said:
Curtis said:
I've owned two of those $150 electric pressure washers. They lasted about two car washes. Cheap pressure washers have a lifespan that can be measured with an egg timer. I can build this one for more or less free.
I guess I've had better luck...my Karcher electric is probably 10 or 15 years old and it still works fine.
My Karcher lasted the best of all of them; about five uses in one year. Just long enough to get me past the warranty. This one I'm doing will get used almost daily. That kind of duty cycle isn't what inexpensive electric pressure washers are for. Fantastic for car washing and cleaning off the patio a few times a year, but not daily abuse. Not poo-pooing your machine, just not really up to the task I need.
Going component also means not having to deal with proprietary parts. If a Home Depot $150 special breaks, chances are the part will cost more than $150 and I have to wait two weeks for it to ship from China.
How about a swimming pool motor? Take a lot of abuse, push a fair amount of water, last a long time. Hell, mine had been left out in all kinds of weather. WD-40, and away it goes. Not sure of shaft sizes, but hunt for someone jettisoning one. May work.
Good call. Most of them are big shaft, but worth a look
