Dockside Chat - How does a power washer work?

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View Full Version : How does a power washer work?


glacierbaze
03-25-2012, 10:01 AM
Specifically, what kind of pump do the common, lawn mower sized ones use? Is it an impeller, similar to an outboard? I am looking for one on CL, and see several with almost no usage, but the pumps don't work due to sitting for a long time.
In googling, I see that at least some pumps have oil in them. Would low oil in the pump cause it to nor pump water?


bladenbullet
03-25-2012, 10:09 AM
this is a quick search but it might help...

http://www.the-power-washer-advisor.com/how-pressure-washers-work.html

glacierbaze
03-25-2012, 10:20 AM
Thanks, what happens if someone runs the engine without the water turned on? Can that burn up a pump?


islandpressure
03-25-2012, 10:26 AM
Glazier blaze, yes the pump will burn up. My business for 17 yrs

bayrunner16
03-25-2012, 10:28 AM
I have done a good deal of power washing. My pops had a side business for years.

Pops refused to buy anything other than Cat pumps for all his trailers.

They were/are direct drive and you will burn them up running them dry.

BACKTOTHESEA
03-25-2012, 11:13 AM
Generally the pump uses pistons in series to pressurize the water. It is similar to the desgn of a combustion engine. You have a crankshaft, connecting rods to the pistons and bearings that the crank rides on. This is usually housed in an alloy assembly and immersed in oil.

This is what I learned rebuilding my pump on a mid sized (3500 PSI) residential model with direct drive. In freezing temps you should run some antifreeze through the pump. My ceramic pistons somehow cracked and needed replacement. Probably from allowing to run too long at times and overheating without actually using the pressure washer.

New pumps seem to run close to 1/2 the price of a similarly powered new machine +-. Assuming the housing is good, the parts seem to run close the 1/2 the price of a new pump (new pistons and seals).

Ghetto Lobster
03-25-2012, 11:51 AM
Even letting them run with water in them and not pumping is no good; They should also be stored with RV anti freeze in the pump unit not only to protect from freezing but for lubricity purposes. Better off buying a new one than the possibility of dealing with somebody else''s problem.

GWcpa
03-25-2012, 12:05 PM
I blew my pump up but the 5 hp Honda is fine. What's the best way to buy a new pimp or am I better off buying a whole new washer and sell the Honda?

I blew it up letting it run too long without washing. Overheated the pump. Did not know this could happen.

Sent from my iPhone using Forum Runner

FASTFJR
03-25-2012, 02:58 PM
http://www.youtube.com/watch?v=Mg2JSyxGezo

Boataholic
03-25-2012, 06:13 PM
try here for parts

http://www.northerntool.com/shop/tools/NTESearch?storeId=6970&N=0&Ntk=All&Ntt=pressure+washer+pumps&Nty=1&D=pressure+washer+pumps&Ntx=mode+matchallpartial&Dx=mode+matchallpartial

glacierbaze
03-25-2012, 06:24 PM
Thanks again, I guess I will stick to ones that are in good working order.

WillyC27
03-25-2012, 06:45 PM
I just picked up one of these .... http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?productId=203051642&storeId=10051&langId=-1&catalogId=10053&ci_sku=203051642&ci_kw=%7bkeyword%7d&kwd=%7bkeyword%7d&cm_mmc=shopping%2d%5f%2dgoogleads%2d%5f%2dpla%2d%5 f%2d203051642&ci_gpa=pla ......It's got plenty of power

TheRealMacGyver
03-26-2012, 10:58 AM
It's pretty much already been said in this thread, but the homeowner models will self destruct with no water very quickly. As a rule on mine I always follow these unbreakable rules:

1. Always connect water hose, turn on full blast and let it run through the pump for several minutes. This gets any air out of the system.

2. When the engine is running, I NEVER release the pressure valve/handle for more than 30 seconds at a time. I will just spray into the air if I am moving something like the hose around just to keep water flowing. (the pump will overheat quickly otherwise)

3. Always purge the pressure after shutting off the motor, then let the water flow for several minutes to cool pump down.

If you disconnect the hose from the wand the water will just flow through the pump.

AND, never loan a pressure washer out to a friend, because they will probably fry your pump!

triumphrick
03-26-2012, 02:14 PM
I have replaced the standard issue pump on my DeVilbis Excel with an upgraded model that has lasted me for years. If you google "upgraded pump for pressure washers" you will find a wealth of information.

This is where I ordered my parts...and found some of the best prices...
Devilbiss Excell pressure washer EXWGV2121 parts breakdown owners manual (http://www.ppe-pressure-washer-parts.com/devilbiss-excell-pressure-washer-exwgv2121-parts)

WillyC27
03-26-2012, 03:46 PM
It's pretty much already been said in this thread, but the homeowner models will self destruct with no water very quickly. As a rule on mine I always follow these unbreakable rules:

1. Always connect water hose, turn on full blast and let it run through the pump for several minutes. This gets any air out of the system.

2. When the engine is running, I NEVER release the pressure valve/handle for more than 30 seconds at a time. I will just spray into the air if I am moving something like the hose around just to keep water flowing. (the pump will overheat quickly otherwise)

3. Always purge the pressure after shutting off the motor, then let the water flow for several minutes to cool pump down.

If you disconnect the hose from the wand the water will just flow through the pump.

AND, never loan a pressure washer out to a friend, because they will probably fry your pump!

Good advice....;)

Surprised you didn't say any repairs only needing a swiss army knife and duct tape

camnbo
03-26-2012, 03:51 PM
What's the best way to buy a new pimp or am I better off buying a whole new washer and sell the Honda?
Sent from my iPhone using Forum Runner

I didn't think you could buy a new pimp. I always thought you were pretty much stuck with the one you have until they cut you loose. Good luck!!:grin:

thajeffski
03-26-2012, 04:00 PM
awesome, I bought one mid summer last year and it's been outside in a shed all winter. I wonder if it'll work this week when I need to spray the boat.



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