# Nilfisk pulsing - second replacement



## 156pilot (May 8, 2011)

*Nilfisk pulsing - second replacement - now giving away for free*

So: I bought a C120 a couple of years ago. It started misbehaving - occasionally pumping away when there was no flow through the lance, graduating to a permanent pulsing, then frequently reduced pressure, and eventually cutting out completely (overheating?). I got it replaced under warranty and now the second one has done the same.

There's a few threads on this but most seem to relate to pulsing in the sense of changing flow rate; mine is running the pump when no water is flowing through, i.e. the trigger is not pressed. Water pressure is fine, as it always has been, and there are no obvious leaks anywhere.

Is it worth attempting to fix it? I can buy a new Centennial for £85 and possibly sell off the duplicate accessories.

The other question is why is this happening? This is in an area of hard water and there was a bit of limescale in the intake filter, but I try and look after it and empty it of water after using it.

I'm not really complaining about the product, by the way - it got a decent amount of use and is generally very good - it's just a shame it doesn't last as long as it might.


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## Corfate (Dec 23, 2013)

Mine kind of does the same.. When i turn it on, the pump runs for about 3 minutes, then pressure dies completely, so it runs for another minute or two before the pressure is actually adequate to blast out the gun..


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## Rascal_69 (Sep 20, 2009)

My karcher is about 2 years old. 

It started pulsing to my shock last week.

I have been using my old lance from previous karcher. Now close to 4 years old. So I switched to new lance that I got with currant one - pulsing away. 

So old lance is away in bin and now using the lance that came with it. 
Pretty shocked it's still going strong.


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## 156pilot (May 8, 2011)

Mine runs the pump on and off every 1-2 seconds; if you press the trigger, it's hit and miss whether you get high or low/medium pressure out of the thing, except it will generally stick at that rate - it's happy whilst continuously working. As soon as you let it idle, the problems start.


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## Beancounter (Aug 31, 2006)

^^^ Exactly the same here


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## 156pilot (May 8, 2011)

Beancounter said:


> ^^^ Exactly the same here


What's your area like for limescale? I'm in Hampshire and it's all chalk around here, so I'm guessing it may be related to this.

I did run some Viakal (household limescale remover) through it but short of looping input and output through a bucket of descaler, I don't suppose there's much that can be done.


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## Beancounter (Aug 31, 2006)

We're in a hard water area too - maybe that's the problem.

I'm going to drop Nilfisk an email and see what they say, but I think I'm near the 3 year mark now, so the chances are I'll just grab a new one when this one finally dies. Shame as it's not affected the performance, just an annoying trait that is rather noisy


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## 156pilot (May 8, 2011)

Let me know how you get on.

It might be possible to filter the input but I haven't seen any inline filters that will either give a decent throughput or cost less than the annual replacement of the PW.


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## svended (Oct 7, 2011)

Are you properly priming the pump. Ie running the water through the pressure washer while its off but with the lance on the end till the pulses stop and you get an almost constant stream. Then let go of the trigger and turn on the washer and you should be okay. I found mine only pulsed or 'went hunting' if there was air in the hose, only needs a small amount to ruin your day. Before putting it away, run some water through it while turned off then once unplugged from the water and power supply pull the trigger to release any pressure. 
It sounds arsie but that what the instruction recommend and I've not had a problem with any washer since.


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## 156pilot (May 8, 2011)

svended said:


> Are you properly priming the pump. Ie running the water through the pressure washer while its off but with the lance on the end till the pulses stop and you get an almost constant stream. Then let go of the trigger and turn on the washer and you should be okay. I found mine only pulsed or 'went hunting' if there was air in the hose, only needs a small amount to ruin your day. Before putting it away, run some water through it while turned off then once unplugged from the water and power supply pull the trigger to release any pressure.
> It sounds arsie but that what the instruction recommend and I've not had a problem with any washer since.


I don't routinely do this, no.

When putting it away, I usually run the pump to get rid of any water in the system. I didn't do this with the first one I had.

When not in this problematic state, then once connected to the hose it comes up to pressure and switches off the pump very quickly. It never pulses in the sense of struggling to maintain flow through the lance.

I suppose there must either be a sensor fault or it's losing pressure on the HP side.


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## Beancounter (Aug 31, 2006)

I do occasionally prime the washer, but I've found that this makes no difference at all.

Like 156pilot says, sounds like it's a sensor problem, as mine didn't do this 6 months ago. I have no flow restriction fittings on the hose either so the flow from the tap is uninterrupted.

I'll update if i hear anything useful back from Nilfisk.


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## Beancounter (Aug 31, 2006)

Right, being a man of little patience   I called the Nilfisk helpline (01768 868995), spoke to a VERY helpful person . 

Apparently the extension lead that I use could be the problem and cause the pulsing................. and the faint whiff of burning too :doublesho. 

This ties in with a recent change of extension cable, so I'm hoping that could be the problem. I will try it later this week off the mains socket and see if that cures it. Extension cables should be 2.5 core to run the Nilfisk which I know my old one was, I recently switched to a longer but lower core cable...

Here's hoping


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## Rabidracoon28 (May 31, 2012)

Well you learn something new everyday. Thanks for sharing beancounter 😉


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## Beancounter (Aug 31, 2006)

^^^ Agreed, I would never have checked the electrical supply in a million years. I'm hoping it is the cause and I wonder if it will cure other's problems too. Will update as soon as I've had a chance to test.


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## T.E.D. Jordan (Feb 13, 2013)

You should ALWAYS prime a pressure washer. As said, connect water, let water run through the washer with you pressing the trigger for 30 seconds or so and then use it as intended. You'll fast wear a pressure washer out otherwise. 

Jordan


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## svended (Oct 7, 2011)

I've just changed my extension cable, a cheapy one at that. May pop round to Screwfix for a propper splashproof one just in case. 
Thanks Beancounter. :thumb:


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## 156pilot (May 8, 2011)

Unless something corrodes, I can't imagine power is my issue, since I've been using the same extension cord throughout.

Based on this thread, I'll make sure I prime the next one. I'd be interested in what would wear and why - the pump, presumably, from trying to pull air?


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## Beancounter (Aug 31, 2006)

I'd be inclined to try yours straight off the mains if possible 156pilot, given that you've had a few machines and they have all had problems and you say that you've used the same extension lead, maybe that is the cause?
Got to be worth a try


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## 156pilot (May 8, 2011)

I have actually tried that before - same for hoses and all the other factors you can think of. The only possibility in that regard is that something is doing damage over time.


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## Beancounter (Aug 31, 2006)

Ah, I see, fair enough


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## richard56 (Sep 29, 2013)

Try this,
When it next starts pulsing, remove the nozzle from the end of the lance.
Top tip, roll your sleeves up!
If the washer runs normally there is grit blocking the jet in the nozzle.
On the back of your instruction manual is a pin. Push pin in nozzle and wiggle it.
This happens to me quite a lot. I run the washer from a tank, I am sure it has grit inside the tank. I shall give it a good flushing out one day.


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## Beancounter (Aug 31, 2006)

^^^ That's fine for when the machine is pulsing whilst 'in use', but mine pulses when it should be idling, ie I'm not pulling the trigger to activate it.


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## richard56 (Sep 29, 2013)

Oh right, scrub that then.
Hope you get it sorted.


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## 156pilot (May 8, 2011)

Well, I gave up fiddling and bought the Centennial. £85 at Homebase, then minus 10% for some reason, and then add £20 for a no quibble three year warranty, which I'll probably wind up using 

That makes the ownership cost about £30 a year which I can live with just fine. It's a shame to scrap the old one (anyone near Southampton/Portsmouth is welcome to it if you let me know ASAP) but such is the nature of things these days.


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## Beancounter (Aug 31, 2006)

Well, I got around to running the pressure washer off the mains power this weekend and I can report......... that it's made absolutely no ****ing difference at all.
So back to the drawing board for me. Just pulses when idling so I guess it could be a sensor somewhere.
Another call to Nilfisk tomorrow I think.


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## Sean_Jaymo (May 24, 2006)

Mine does this but I'm sure it's down to the water in our area being quite aerated. The extra air in a static line causes pressure drops and that causes the pump to momentarily pulse to prime itself. I live in Lincolnshire currently and when I used to live in Oxfordshire or take the same pressure washer back there, the pulsing stops. 

I just turn it off at the unit until I need it again.


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## GleemSpray (Jan 26, 2014)

Have you got an auto shutoff connector on your hosepipe? You know the sort where you can change the spray fitting without turning off the water? 

They used to cause my old Alto pressure washer to surge and stutter and cutout and do all sorts of weirdness.


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## Beancounter (Aug 31, 2006)

^^^ - no, have known about those and the way they'd restrict flow (minus 30% I think I read) so my set up doesn't have any fitted between the tap, the reel or the machine. 
Clearly something's setting it to pulse, but can't work out what


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## GleemSpray (Jan 26, 2014)

My Alto occasionally pulsed when idle for several years before I changed it last year for a Karcher. 

The pulsing didn't seem to affect performance.


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## Beancounter (Aug 31, 2006)

^^^ That's the weird thing, there is no adverse affect on the performance, it is just annoying 

Probably just one of those things I'll live with, but if anyone has any other ideas, please pop them up. :speechles


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## 156pilot (May 8, 2011)

I do have auto-shut off connectors on my hose but the water pressure is excellent and it makes no difference; again, unless it contributes to wear.

One thing I have noticed is that the replacement unit is significantly more powerful. I wouldn't have said the old one was down on power but this makes a big difference on how much dirt it can get rid of, so it probably dropped off over time.


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## Beancounter (Aug 31, 2006)

I must admit, I'm say here this morning and now inclined to just bite the bullet and get a new one and retire this one to patio duty.


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## Tesla (Mar 1, 2007)

Beancounter, did you ever resolve this? My identical washer is doing the same thing.

I've always primed the pump before use. The washer works fine but when idle the pump will spin up for 1-2 seconds every 20 seconds or so. It's a bit annoying but otherwise is working fine. I was going to contact Nilfisk as mine's not been used much and I think is about 18 months old.


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## salsa-king (Dec 17, 2013)

my c120 did the same pulse every few seconds, maybe I burnt it out jet washing a block pave drive?... i bought a new one tho.. the next model up. seems fine so far.


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## MDC250 (Jan 4, 2014)

Oh dear mines started doing this 

They don't cost the earth but still a little frustrating.

I've started using a jet wash on the way home from work...£1 for 5 minutes, hot water and whilst the shampoo will undoubtedly be cheap rubbish only use a little as take some VP Citrus on a pump sprayer. Get funny looks when I spend way more time drying and sorting trim and putting on BSD :lol:


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## cossierick (Jan 19, 2011)

I suppose id best add to the list. 

Me and my brother both got a c120 at the same time(they were on offer at screwfix) 

His packed in first, did the usual pulse during idle then eventually packed in. mines now started doing it so im getting ready for it to stop. 

His has allways been plugged into the mains in the garage but they do have crap water pressure up there ?
Mines been allover the place lol but seams to be lasting a little longer.

rick


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## Dipesh (Oct 12, 2007)

Mine started pulsing, a quick look and the O rings were perished on the pipe. I replaced these and it's perfect again. 

It's been a great PW, so reliable compared to the crap karchers I had before.


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## STUOOBY (Dec 26, 2012)

mines used to pulse aswell. but what i do now is connect the hose to the washer and turn the water on. but leave the washer disconnected from the power. pull the triggar for 30 secs to let all the air run out the machine. then plug in. never ever pulses. had the machine for 4 yrs now. and it has seen some heavy use over the yrs.


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## Will ST (May 27, 2007)

Dipesh said:


> Mine started pulsing, a quick look and the O rings were perished on the pipe. I replaced these and it's perfect again.
> 
> It's been a great PW, so reliable compared to the crap karchers I had before.


Same here, new O rings and a little bit of red grease on them, been perfect since.

Noticed little dribbles of water at the lance connection and it was pulsing occasionally when on stand by. After hearing the occasional horror story, I was expecting the worse. Best 5 pence repair ever  Old ones were a little worse for wear and starting to age and split.

Worth checking before splashing out on a new PW


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## footfistart (Dec 2, 2013)

My karcher 520m did this was working fine and then started to pulse. Cleaned the filter out and it made it worse. Then I found it had a cracked cylinder head so with all new parts and o rings it was more expensive than buying a new k2. For 59 in tescos


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## bigup (Jun 4, 2009)

my nilfisk is around 5 years old now, a c120

pulsates when washer is idle, does my head in, every 5 secs it pulses

runs ok when trigger is pressed and rinsing the car though

think its time i get a new one


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## SuperchargedLlama (Apr 25, 2008)

Mine does this as well, not constantly or anything, just a little pulse every now and then. I always assumed it was just "re-pressurising", like it had a sensor, detected the pressure in the loop had dropped a bit so it gave it a nudge to get it back up - like a compressor does.

Am I completely wrong or an utter genius?


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## smegal (Aug 14, 2009)

Are you sure it's a fault?


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