On 14 Apr, 21:43, "The Medway Handyman"
wrote:
Sparks wrote:
"The Medway Handyman" wrote in
dia.com...

Mark X wrote:
I notice that Makro are often selling petrol pressure washers cheap.

Is it worth having a petrol version or should I just get an electric
Karcher from B&Q?

Pro's; *Much more power usually available 5hp petrol machine = same
power as 3hp electric, most DIY machines are around 2hp max. *Work
anywhere you can get water.

Cons; *Cheap petrol engines can be trouble, IMO only worth looking at
Honda. Higher service cost. *Noisier than electric, cost more to run.
Auto stop/start not possible so engine must be shut down within
minutes of closing trigger gun.

Really? - don't they just have a bypass valve in them, so water is
just pumped in a circle?
My old electric Karcher certainly does this!

By pass machines (electric or petrol) can only run in by pass mode for a
very short time. *Each time the water goes through the pump, through the by
pass valve, back into the pump, through the by pass etc it picks up a little
heat from the friction of the pistons through the seals.

The pump head on a pressure washer contains a very small amount of water -
an egg cup full approx. *Doesn't take long for this to reach a high
temperature - which will soften the pump seals & allow water to get past
them into the oil in the crankcase. *5 mins on a cheap pump, maybe 15 mins
on a good one & your seals are buggered & possibly the swash plate &
bearings if the oil is contaminated enough.

Thats why auto stop via a pressure switch is such a good idea. *Not perfect.
Best solution, only found on industrial machines is a by pass valve with a
flow switch which detects flow through the by pass & turns the motor off -
sometimes via a timer.

--
Dave - The Medway Handymanwww.medwayhandyman.co.uk



My petrol (Briggs & Stratton 5HP) never gave me a moments trouble in 7
years of daily
using it commercially. Mind you, it was a "Cat" pump, not a bloody
awful swash plate pump.