Hi there, got my new rig (Honda GX690 with Comet pump on trailer)… connected water supply, started engine, unreeled high pressure hose and opened main valve… The pressure gauge flew into the air! Anyone know why this occurred?
Can anyone help please with advice on the pressure gauge blowing off?
There were no kinks, water supply was good.
This machine was being used for the first time.
Alas, it is back in my lock up now…
Probably a little water hammer effect would be my guess
Thanks but I wasn’t closing the main valve, the gauge blew and flew off when opening the main valve. Dodgy gauge? How much damage will need fixing to a brand new machine?
The gauge flew off because you opened the valve and it got an instantaneous spike of pressure and those gauges are quite cheaply made.
While it is nice to know your spike pressures at the pump, I can assure you that as long as your unloader is adjusted correctly for the tips you use you’ll almost never use a gauge again. And, when you do use a gauge, put it at the gun so you can see what kind of pressure you’re actually getting at the cleaning surface.
Thanks heaps for the reply. So, the fix is a better quality pressure gauge? It’s that correct? Would that stop this happening again? Do you think I opened the main valve too quickly or something like that? Engine revs too high perhaps? What could I have done wrong? This thing is brand new. Could it be damaged now?
Additionally I could get a gauge placed at the gun end I suppose but I already have a ball valve there and the gauge would get battered when reeling in. Would adding extra “moving parts” to this line make for more future problems? Knowing the pressure at the pump will not give me the true pressure at the point of the gun but it will only be a few 100psi less at the gun end… Not more right?
Lol the mental picture of a gauge banging along the ground while reeling the hose in was funny.
No, you wouldn’t “hard-mount” the gauge at the gun. You’d have it on quick connects so you can hook it up, check pressures, and then remove it for actual use.
It’s unclear where the gauge is mounted currently but, typically, you’d swap one of the plugs on the top of the pump manifold for one that has a threaded port for that gauge to thread into. That way, you’re seeing the actual pressure at the pump.
I’ve never seen a gauge fail like you have experienced but, hazarding a guess here, when you threw that valve open it spiked in pressure and the spike was too high for that particular gauge. It may have been faulty from the factory or damaged in shipping–who knows.
If you’re dead set on having a gauge on the machine, mount it on the pump manifold like I described above or, better yet, put quick connects on a gauge so that you can see your pressures at the gun and then remove the gauge once you’re satisfied with your pressures.
Yes, your pressure at the gun end will be a few hundred psi than at the pump end. What you need to be concerned with is how high your pressure spikes when you release the trigger. That’s why that gauge was placed near the machine. Ideally, it would be on the pump itself to get a more accurate reading.
The fix is to trash the gauge and put a plug in that port. You don’t need a gauge.
Hi there and thanks again. The gauge was mounted and threaded in-between the pump and the hose. In the image, you will see that I placed the gauge next to the port it flew out of. Must have sheared it’s thread. I could plug up this port by the sounds of it and have no gauge… But, what happens then when there’s a huge spike again? Is something more expensive gonna blow?
Not sure where you’re located but I’ve never seen one mounted like that from the factory or anywhere here in the states. I have an an after market one with the quick disconnects that I can check if needed at end of hose. Think I’ve maybe used 3-4 times in 10 years. Total use is probably less than 2 minutes.
Is that a new machine or one you bought from someone else?
It’s new. My image is just of the port that the gauge flew out of. The gauge is just placed next to it.
What’s going on here, is that some sort of ball valve??
Do us all a favor and take a picture zoomed out a bit. I’m no expert, the other wash vets on here know a lot more than I do.
Good eye!
Here’s a zoomed out image from this side. Pressure gauge was on the port next to the main valve - as drawn in by me (it’s not there anymore because it flew off). This main valve is closed after start-up and then opened again when hose \ gun is set up.
Take it out and plug that port in that T fitting. You already have a gauge at the pump manifold. The one that blew is redundant and, realistically, virtually worthless at that location.
As long as that reel is rated for a higher PSI than that pump spikes at, you would never need to know the pressure entering the reel manifold.
In short, just get rid of it and make sure you use the search bar here to learn how to set your unloader for the tips you intend to use most often.
I gotta say, that’s a pretty slick little unit but that trampoline leg frame is just a disservice to an otherwise pretty well put together machine.
One more thing! Either eliminate that ball valve or always leave it open and be sure to open that ball valve at the gun before you start your machine.
My start-up process is this:
Hook ball valve to hose end and open it.
Unreel all the hose and place the ball valve somewhere that I can see it.
Pull choke lever completely out. Put throttle lever to about the 1/3rd full throttle position.
Turn key and start engine. Let it run for 5 seconds or so then push choke lever all the way in. Slowly raise throttle lever until it’s at WOT.
Walk to end of hose and turn ball valve off. You will hear the machine bog down for a millisecond before the unloader open up and recirculates water back to the tank.
Start washing.
You really shouldn’t have any restriction of flow when starting your machine. You want it to be able to turn over as freely as possible. With the way you have it now, it is building up pressure in that line leading to the ball valve at the reel. When you opened that ball valve, that pressure instantly slammed into that gauge and since that gauge is plumbed directly across from the inlet port it took the full brunt of that impact.
Thanks for the advice. My process is:
water supply on
fuel supply tap and all valves open at start up
start engine (with choke)
close choke and set to max revs after 10secs
close main valve to set up gun etc
open pin locks and brakes to unreel hoses
apply brake to hoses at desired length
open main valve to use
start washing
stop washing
idle at half revs and cut off water supply
let engine cut out
apply pin locks and brakes to hoses
switch off ignition and close fuel tap
You’re doing a lot of extra steps you don’t need to do.
I will let the other guys elaborate, but I do always hold the gun trigger open when starting.
I keep the ball valve attached 24/7 & have never had to open it for the engine to start. Start up instructions that came with the GX630: 1/3 throttle, pull choke & slowly close. Let it run for 2-3 minutes before going full throttle. It’s best to set things up for ‘as much as it can do’ & not worry about the numbers, I think.
