[Matt Gibson]

Right, I bought a new machine, had to replace a split hose, did that today, now ive noticed that its not holding pressure. Keeps pressuring up then dropping. Checked all fittings, no leaks, not even any drips. Unrolled hose from reel no splits/leaks.

Unloader sounds a bit noisy though, like a knock inside it. Im thinking a new unloader, but thought id ask about first. What do you think? Will a buggered unloader cause pressure to surge?

Also, there seems to be two unloaders. One normal one, then wnere the hose goes from the unloader tothe boiler, there is another unloader.

What is the purpose of two unloaders?

[chris scott]

Post a picture!

[Matt Gibson]

Its down at the lockup. I got fed up trying to find the leak and came home..

[Kenny83]

pressure feed it and check for leaks on the inlet? may be sucking in air?

[Matt Gibson]

Dont think it would surge like that if it was sucking in air... Sounds like its getting up to pressure then losing it somewhere, and having to pressure up again. I watch the gauge and it drops to a point then pressures up..

..Or would sucking in air give it these symptoms?

[chris scott]

Or a blocked inlet filter   ....a picture paints a thousand words. Well it is valentines day xxx

[BDCS]

The first unloader is the main unloader and this would be the worn one. The face inside will be worn which allows the trapped pressure to decay which then means it loads up to replace the pressure lost. The second unloader is probably a relief valve, this is because the boiler is probably rated at 200 bar and will be set just above that. That may also be the cause of the first unloader ramping up and down if the boiler valve is set below that of the first unloader. Remove the return hose from the second valve and watch the return line to see if the water comes out of this when the main unloader loads up if not then its the main valve as mentioned first. Makes sense to me at least - ring me if its not clear

[Blast Away]

Or a blocked inlet filter   ....a picture paints a thousand words. Well it is valentines day xxx

I'd agree to this one. Check this first Matt. Our filter gets blocked with leaves and stones all the time on the trailer as it's fed from the bottom of the tank.

[BDCS]

I assumed the problem was unloading and not washing - sorry 

[Matt Gibson]

ok, to be clear, when i pull the trigger, i get good solid constant pressure. no problems.

When i let go of the trigger, it builds pressure, then that pressure drops so it builds pressure again. Just like if there was a leak on the hose/fitting/reel etc.

Thats why i assumed it was the unloader. the pressure builds up nicely, then you can see the needle on the gauge start to drop and then it will rev up and build pressure again.

I didnt think a water feed issue would cause this, but ill check the filter tomorrow.

[BDCS]

Ok then read my post and check each valve and their pressure setting

[Matt Gibson]

Ill be back down there tomorrow so ill give the second unloader a check. The second unloader doesnt have a return. It has an inlet/outlet/gauge coming from it/and a second outlet which just vents to atmosphere. kind of like a pressure release valve. Im guessing thats what it is.

Also, today when i was testing it all out, even if i set the(first) unloader really low, it still builds/drops pressure, so im assuming the second unloader is set high,

[Kenny83]

Thought you meant it was hunting when you were pressing the trigger...
 

[chris scott]

Check the little plastic valves in the pump head as well as the unloaders.

[Matt Gibson]

Yeah i thought it might be a valve. ill check them all out tomorrow.

just read my message above about describing the second unloader. i didnt give a very good description. the second unloader is exactly like the first. inlet and outlet. where the return to tank should be there is the pressure gauge. then there is another outlet which just has a piece of pipe on it.

Two unloaders, this thing is gonna cost me a fortune in maintenance. might just get rid of the second unloader..

[BDCS]

Well what was the outcome ? Just a shagged unloader ?

[Matt Gibson]

Dont know. Was out spending money with the Mrs

I ordered a new unloader this morning anyway so hopefully get it tomorrow.

[Matt Gibson]

Outcome was a dud unloader. Put the new one in and it sorted the surging.

This machine is set up different to mine, still trying to work it all out.

Another difference, when i pull the trigger, the full pressure isnt instantly there, it takes a second for it to build up out of the nozzle. With the trigger released, the engine revs nicely, then you pull the trigger and the engine revs louder and the pressure builds to full pressure(only takes a second)

With my other machine, you pull the trigger and the full pressure is there instantly, Not sure why this new machine doesnt do the same, is it because of the way its set up? pump? unloaders?

Picture of the two unloaders

[Kenny83]

sounds like you have a K5 unloader, as opposed to a trapped pressure unloader, K5's are better as they dont put any jerking or stress onto the shaft and keyway... also you have a low rev cut out pressure switch, reduces revs whe n trigger is depressed, which will explain the switch that was on your pump the other day, sounds like a very good set up mate

[Kenny83]

Is this a hot and cold machine matt? I can see you have a flow switch on there for a boiler.... the other unloader may be a tempaerature blow off?