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OT: PRESSURE WASHERS


JST
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i am sure someone on here will know and although its OT is may be of help to others!

i have just got myself a nice hot water karcher pressure washer.

only problem is that the pump doesnt always kick in (on demand) when the lance trigger is depressed. in fact it rarely kicks in.

However if i remove the nozzle on the end of the lance and squeeze the trigger the pump always kicks in. (due to the increased flow i guess)

i am therefore assuming, and hoping someone will confirm i have a water pressure problem and need to increase the water feed?

If thats the case will upgrading to 3/4" pipe from a 3/4" tap help (current tap is 1/2 with 1/2 pipe and stepped down from 3/4" supply)

the manual (well if it came with one that would help) but the web says it should have a 3/4" feed anyway but i got it 2nd hand with a 1/2 pipe and thats how the last user used it.

thoughts?

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I had the same with mine, it just squirted at normal mains pressure.

I found that if I pulled the trigger with the power off and then switched on it worked every time.

There is a relief valve that bypasses the pump when the trigger is shut, I took it to bits and cleaned it and all seems OK.

You could try reducing the mains pressure, I was wondering if too high mains pressure would stop the valve closing and thus reduce the output pressure.

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i can get it to work by turning it off, sqeezing the trigger to release the pressure in the pipe, release the trigger then turning it on again, pump kicks in straight away and if i squeeze the trigger then it will work fine. until i let go of the trigger again then it goes to hoot!

maybe too much pressure then? and the water supply can cope on its own with pressure for it to come out of the nozzle? or so the pump thinks?

Jim - its a FBH so cold water supply. all the FBH bit works fine

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i am sure someone on here will know and although its OT is may be of help to others!

i have just got myself a nice hot water karcher pressure washer.

only problem is that the pump doesnt always kick in (on demand) when the lance trigger is depressed. in fact it rarely kicks in.

However if i remove the nozzle on the end of the lance and squeeze the trigger the pump always kicks in. (due to the increased flow i guess)

i am therefore assuming, and hoping someone will confirm i have a water pressure problem and need to increase the water feed?

If thats the case will upgrading to 3/4" pipe from a 3/4" tap help (current tap is 1/2 with 1/2 pipe and stepped down from 3/4" supply)

the manual (well if it came with one that would help) but the web says it should have a 3/4" feed anyway but i got it 2nd hand with a 1/2 pipe and thats how the last user used it.

thoughts?

I have a Karcher hot water washer running from 1/2ins copper pipe along the factory (60 metres) 1/2ins tap and 1/2ins plastic hose, it does occasionally suffer from lack of water so if you have 3/4ins switch without delay. Does the inlet to the machine have a bayonet connector with a rubber seal? If previous owner has used 1/2ins tail this could be a starting point to change. If the previous owner did not use correctly then suspect a problem with the heater.

THIS IS IMPORTANT when using hot water and you want to get a cuppa, turn the truck round etc DO NOT JUST TAKE YOUR FINGER OFF THE TRIGGER YOU WILL DAMAGE THE HEATER AND PUMP. Turn the heat control to cold and keep running water through the washer until the high pressure water is running cold. If you leave hot water in the system any minerals will block the pump / heater just like your kettle, especially a problem here in Sussex with our water coming off chalk hills. I know this due to a hefty repair bill :rolleyes:

When finished with the washer turn off the water supply tap, press and hold the trigger, high pressure water will flow for 5 seconds, keep the trigger pressed and undo the lance connection to the machine. Now take your finger off the trigger and disconnect the water inlet. The pump will keep running and empty the system of water about 1 to 2 mins is sufficient or no more water ejected. Without water in the system safe for freezing conditions and less of a blocking problem if in a hard water area.

Shout if you need more help :D

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If its a diy level Karcher I thought you were supposed to bleed them through before switching them on.

If its a big boys diesel heated jobby I found blowing the lance nozzle through to clear any grit lodge there sorted it

Any pressure washer turn on the water and with pump switched off press the trigger until water flowing through lance.

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lance is clear. and all parts of the washer work the diesel heater the controls everything it just wont kick in the pump when the tirgger is pushed unless the machine is turned off, pressure released in the lance and then machine turned back on as it repressurizes the lance pipe sqeezing the trigger gives me flow again!

cheers the tips of making sure all the hot water is out NAS90, and already do the latter points of clearing the machine and hoses or water.

so from above

too much pressure/

or/and

clean the relief value (but where would i find it?)

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lance is clear. and all parts of the washer work the diesel heater the controls everything it just wont kick in the pump when the tirgger is pushed unless the machine is turned off, pressure released in the lance and then machine turned back on as it repressurizes the lance pipe sqeezing the trigger gives me flow again!

cheers the tips of making sure all the hot water is out NAS90, and already do the latter points of clearing the machine and hoses or water.

so from above

too much pressure/

or/and

clean the relief value (but where would i find it?)

Tell me exactly which model machine you have.

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connector - err same as air tools one in design, push in with outer collar to release.

This is the type you need, item is the part that would be on the machine, cannot quickly find the mating part that has a tail for the supply hose.

http://cgi.ebay.co.uk/HOSE-COUPLING-BRASS-...3QQcmdZViewItem

My machine is a HDS551C about 4 years old from bought new.

One problem I had was with the power on switch to the pump. Lift the lid and looking from the handles on the right above the pump is the oil reservoir. Under this reservoir is the brass manifold. Sandwiched in the manifold there is a plastic power plug that has a 'U' shaped steel locking mechanism. Pull this lock. Underneath is a rubber cover, pull the cover. Under the cover a brass plunger that can get damaged / dirty and try to clean / inspect this part.

However, I have a sneaky feeling that the previous owner did not follow my words of wisdom regarding not leaving hot water in the system. I suggest that you get your local dealer to check the machine especially as you bought it secondhand.

I do not know where the pressure relief valve is situated.

Definitely if you have 3/4ins hose switch to the larger bore.

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cheers for the help guys, esp NAS90 - thank you

i dont think its too big a problem though as with the nozzle (which has been cleaned) removed the pump kicks in EVERY time (as the water pressure drops quickly so it needs the dmd) its only with the nozzle fitted that i doesn't kick in (well it does 1 in 20) that led me to think water pressure issue. but if yours is running OK from 1/2" this one should as well.

i feel a trip to MVF coming on tomorrow to collect a 3/4pipe etc and bayonet fitting for the washer end.

having said that our flow rate is 10L/min from 1/2" tap and pipe so it should be OK (it need 8l/Min)

so on second thoughts maybe it is more troublesome!

will also try it at reduced pressure and see what effect that has.

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James,, am pretty sure our old washer was a 550c, and may still have the destruction's somewhere ! :rolleyes:

Funny feeling ours did the same thing, but for the life of me, can not remember the cause of the problem !! when/if i find the manual, it may remind me !!

Our washers run on 1/2" feed, no problems

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On mine (not a K'Archer) if you take the cover off there is a group three cyclinders, axes parallel to the motor axis. These have the pistons inside, operated by a swash plate.

At right angles to these there is a cross-drilling, the output is at one end with the relief valve at the other under a brass plug.

Remove the plug carefully and there is a simple ball and spring valve inside.

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I've used pressure washers in the past with a ball bearing in the lance (to stop grit entering?). Pointing it straight up into the air/down at the floor or using inertia to "push" the lance sharply forwards or backwards (I can't remember which) while pushing the trigger solved the 'feeble dribble' problem.

Does your machine mean that when you get backspray from whatever you're cleaning, it's warm?

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bl**dy thing

i found the pressure valve that makes makes the pump work on dmd, electrical side of it is all sound so no probs there. cleaned out the plunger and cylinder (it wasnt too bad) and it worked better about every other time, so thats an improvement. Have cleaned it out about 6 times or so now and its getting better.

even washed the truck with it working properly until i tried to use the detergent mix - well that is b*****d, so i decided that i could live without that.

turned it on again and ......... there goes the hose with a nice split in it (the second one!) had the first one repaired yesterday on the way home.

needless to say it wheeled into the garage and left in disgrace. mon will see 3/4 feed sorted for it and another hose repair i guess.

i think the relief valve issue is almost sorted. i also took most of the top of the brass inlets apart and there was no muck or crud in there so things are looking up, just a sticking relief valve and busted hose to sort.

at least having cleaned the engine now i can see where the oil leaks are coming from!

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oil pressure relieft value? where might that be?

i have been cleaning/sorting the water pressure side so far.

out of interest what oil should you run in these things?

He means the relief valve I mentioned earlier, it works in a similar to an oil pressure relief valve on an engine.

AFAIK there is no oil in them.

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