Pressure washer stalling

[Bluemotion]

I’ve a LAVOR hot pressure washer which is a lovely bit of ‘compact’ kit. I’ve swapped the extension over on my lance for the ones on eBay that are sectional and just about reach anywhere with any angle necks. They are the type with interchangeable ’coloured’ nozzles for different angle width jets. The tube is narrower and after using it today on a continuous clean the machine stops dead and resets itself after a short while. I can only think the pressure is too much either in the diameter of the stainless pipe or the nozzle hole as with this set up I can feel an awful lot more power at the tip. When I put the std lance end back on its fine and causes no issues. Anyone played about with pressure regulators or whatever they have?

 

[hotponyshoes]

It's not just the angle that changes with the nozzle colour, they are also available with different orifice sizes and my guess is you have bought ones that are smaller than the original one.

You might find the nozzle from your original lance fits the new one but if not I would try and source the correct size before messing about with adjusting the machine as that's normally a road to disaster

 

[carbon]

The new nozzle is to small, the diameter of the pipe shouldn’t make any difference. As it works ok with the standard lance you could try reducing the pressure when using the new lance but not really ideal unless it’s adjustable with a hand wheel

Edit using it for prolonged periods like this may cause you problems with the electric motor.

 

[Bravheart]

Think you need to find the flow rate from the pump and buy the correct lance and nozzle

 

[brightspark]

I’ve a LAVOR hot pressure washer which is a lovely bit of ‘compact’ kit. I’ve swapped the extension over on my lance for the ones on eBay that are sectional and just about reach anywhere with any angle necks. They are the type with interchangeable ’coloured’ nozzles for different angle width jets. The tube is narrower and after using it today on a continuous clean the machine stops dead and resets itself after a short while. I can only think the pressure is too much either in the diameter of the stainless pipe or the nozzle hole as with this set up I can feel an awful lot more power at the tip. When I put the std lance end back on its fine and causes no issues. Anyone played about with pressure regulators or whatever they have?

theres your answer then use the proper size jet that is fitted as standard i wouldnt muck about altering pressure regulators . if it has a pressure gauge fitted mine has you can see what the problem will be

 

[Bluemotion]

Not sure how you’d calculate a std issue jet as it’s the usual twist for fan shape type. It’s good to know that there’s so much choice and variables.

 

[brightspark]

if there is a pressure gauge fitted it will tell you if theres any diffrence on jet size fitted

 

[Bluemotion]

Unfortunately this unit doesn’t. I had an old twenty year old LAVOR cold washer which did and a great bit of kit for just pence but this disappointingly doesn’t.

 

[knighty]

when you stop spraying, does the noise of the pump change? and the burner stop?

if the now nozzles are too small it shouldn't matter, the unloader valve should be letting of any extra pressure... unless it's duff.... check the pump, there should be a knob somewhere on the output of it, no pressure gauge makes this tricky, try turning it down a bit and see what it feels like (screw it out)

also the water and/or the burner could be getting too hot, try running it cold


and/or it's got nothing to do with any of that - is this the first time it's had a long run in a while? check over the motor/fan etc. make sure the vents aren't blocked... maybe in the past you didn't run it long enough to overheat and now you have?

 

[carbon]

if the now nozzles are too small it shouldn't matter,

Some of the unloader valves are flow sensitive and using a nozzle that is to small will affect the running of the machine.

I’ve also recently seen a machine that someone else supplied and the customer fitted a smaller nozzle to increase the pressure. It then started blowing fuses, so they replaced the fuse with a small bolt and wondered why the motor was running hot and melting the plug .

 

[Johnnybravo]

How is your water supply? Might sound odd but I had a similar problem. Machine worked perfectly at work. Brought it home to clean the decking and it would run for a short while before stopping. Turned out the garden hose had fittings that were way too restrictive and it was choking it. The pump was shutting down due to a lack of water. Not saying you are experiencing the same issue,but worth bearing in mind.It’s all fine and well to turn the wick up,but if your running out of water,it’s not going to help.

 

[Bravheart]

Not sure how you’d calculate a std issue jet as it’s the usual twist for fan shape type. It’s good to know that there’s so much choice and variables.

Have a close look at the standard as supplied lance and/or moulded on jet they often have the flow rate written on them somewhere then buy a matching rate.

 

[Pete.]

Jetwash pumps are almost always positive displacement so the pressure is directly proportional to the cross-sectional area of the hole in the nozzle. That's why the industrial gear has (or at least had) bursting discs on the line so that if the nozzle blocked it would pop the disc and not the pump.

As above, it sounds like your jets are too small therefore the pressure has gone up too far for the power in the motor so it's just stopped. You should be able to drill out the static jets dunno about the rotating one.

 

[brightspark]

How is your water supply? Might sound odd but I had a similar problem. Machine worked perfectly at work. Brought it home to clean the decking and it would run for a short while before stopping. Turned out the garden hose had fittings that were way too restrictive and it was choking it. The pump was shutting down due to a lack of water. Not saying you are experiencing the same issue,but worth bearing in mind.It’s all fine and well to turn the wick up,but if your running out of water,it’s not going to help.

mine has a separate water tank supply with ball valve using a long hose restricts and the pump sucks the tank dry after a few mins

 

[knighty]

Some of the unloader valves are flow sensitive and using a nozzle that is to small will affect the running of the machine.

I used to have one like that.... but if there's not enough flow would it not just stick in the unloading/bypass position?

I still stay start with checking the unloader valve

https://pressurewashr.com/wp-content/uploads/2017/07/Pressure-Washer-Unloader-Valve-Locations-Examples.jpg

 

[Bravheart]

Some examples of lance/nozzle flow rates. If the original works fine imo you are now using too small a lance/nozzle. You are lucky the motor is cutting out it was an expensive mistake when I stuck the wrong lance on my engine driven cold washer.

 

[carbon]

Those markings are only the maximum that the piece of equipment will take. The first picture of the lance grip is 45l/m with a max pressure of 4060psi and has no relation to what the pump is capable of delivering. The pump may only be rated for 12 l/m at 1470 psi. Without knowing what the pump is you can’t recommend what size nozzle to fit

 

[Bravheart]

Thats right

Those markings are only the maximum that the piece of equipment will take. The first picture of the lance grip is 45l/m with a max pressure of 4060psi and has no relation to what the pump is capable of delivering. The pump may only be rated for 12 l/m at 1470 psi. Without knowing what the pump is you can’t recommend what size nozzle to fit

That's right.
What I'm saying is look on the original lance for the flow rates and using the pictures as examples of how it may be written then match the lance/nozzles to the original.

 

[Bluemotion]

when you stop spraying, does the noise of the pump change? and the burner stop?

if the now nozzles are too small it shouldn't matter, the unloader valve should be letting of any extra pressure... unless it's duff.... check the pump, there should be a knob somewhere on the output of it, no pressure gauge makes this tricky, try turning it down a bit and see what it feels like (screw it out)

also the water and/or the burner could be getting too hot, try running it cold


and/or it's got nothing to do with any of that - is this the first time it's had a long run in a while? check over the motor/fan etc. make sure the vents aren't blocked... maybe in the past you didn't run it long enough to overheat and now you have?

Yes it hasn’t been run for a few months although it’s actually only six months old and has a pampered life.
Back to the other bit regarding noise, when I ‘release the trigger’ all stops as it should do and goes quiet with but when it cuts out (still holding trigger) and in hot water mode it then has an unusual fan sound running. I did think the burner ‘might’ be running over hot so tested it also totally cold and still stopped working with the aftermarket lance attached therefore not heat sensitive although. The long and short of it is it doesn’t like my lance extension.

 

[knighty]

take some photos with the cover off the machine

lance extension/restrictions etc. shouldn't make any difference, the unloader valve should compensate for all of that