UKC

My Karcher K2 pressure washer is giving off that dry coppery metal smell similar to how your scalextric cars would smell after a hefty session. 

My initial thinking is to just open up the housing and spray the whole thing with wd40 but i'm hoping someone a bit more mechanically minded may have some better advice?

We use it indoors so it's not really ignorable as it might be if used outside. 

thanks. 

Arcing on a switch or some other contact (brushes perhaps)?  I would try to find the source asap as it is possible you could do some further damage if you keep on using it. 

Motor.

Given you description, and desire to spray with WD40, the best solution is to send it to Karcher to fix (which they offer) - far better to pay a little and have it repaired than break it and buy a new one.

Alternatively, if you have a technically savvy partner or friend :

https://www.espares.co.uk/advice/howto/replacing-karcher-pressure-washer-el...

That smell is ozone, in case you were interested (apologies if not).  It's a form of oxygen  (O3 as opposed to O2) and it's often a sign of electrical arcing.  It's created by the action of intense UV light on the oxygen in the air around the arc.

Good advice above. 

If something is arcing that badly (prime suspect would be the motor), dousing the thing in WD-40 wont help, might even make things worse and it's unlikely but conceivable it could even cause a fire hazard.  The chances are that whatever the fault is it will be deteriorating.  An electrical arc is a very corrosive thing to motor brushes, switch contacts or whatever is causing it so even if the smell was not a bother chances are it won't keep working very long.

If you've had it for some time, it could be the brushes have worn out.

Thanks for all the suggestions. It's their cheapest pressure washer at about £70-80, so I'm not sure if they'll be interested in fixing it. 

We use it way more than they're designed for, think they're for the odd patio or car wash we use it every day sometimes for a few hours. It's just the first time ones started smelling, all the others in the 'old karcher cupboard' were retired due to excessive leaking. I'll use it for a bit longer and then look into a new one, thanks all. 

If it’s the same model as your old leaky ones, get a handy person to swap the pump or motor assemblies from an old one.

Do not spray anything that smells like Scaletrix with WD40.  As another poster said, the smell could be indicative of ozone; another possibility is overheating coil wire in a motor giving off chemicals from the insulated coating.  In either case WD40 could go boom boom bang.

And intense UV can decompose some solvents from something mildly bad for you to something deadly, probably not a big deal with WD40 but spraying but you never know. I remember reading a few years back an accident report where someone had died of pulmonary oedema having tig welded over an unfamiliar brand of brake cleaner he'd used to degrease the metal.

OP: Likely the motor brushes. By the sound of it it's had a good life but they may be replaceable. Chances are the next lot won't last long though if the commutator is pitted and burned. Could be an overheating winding, I've had that with a saw which had a bad crimp connection in the motor, smells different but still distinctly 'electrical'.

jk

You will probably find there is a Karcher approved repair centre locally. I have used the one in Preston and it is still going strong after 16 years of use.