squirtgun 122 Report post Posted March 27, 2007 We were on a job tonight when I walked out to find the machine was not by passing water back to the tank.I shut everything down and started running through the filters,connections ect to find out why and came up with nothing obvious. Could the unloader have gone bad? Hurry up guys I need answers NOW,I have a job to complete tomorrow night and it's a 2 hour drive to a new unloader. Share this post Link to post Share on other sites
One Tough Pressure 580 Report post Posted March 27, 2007 If the water is not bypassing to the tank, then where is it going? Does the system bog when you let go of the trigger? Share this post Link to post Share on other sites
Mike Williamson 198 Report post Posted March 27, 2007 We were on a job tonight when I walked out to find the machine was not by passing water back to the tank.I shut everything down and started running through the filters,connections ect to find out why and came up with nothing obvious.Could the unloader have gone bad? Hurry up guys I need answers NOW,I have a job to complete tomorrow night and it's a 2 hour drive to a new unloader. The water is going somewhere....either your pump is broken and not putting out water at all, or it is bypassing, or you have a major leak in your bypass line, or somewhere between the unloader and the gun. The water has to be going somewhere. Share this post Link to post Share on other sites
squirtgun 122 Report post Posted March 27, 2007 No leaks at the pump head,hoses,filters or any connections.That's why I was so perplexed when it happened.I knew the water should be going somewhere. Went out this morning and everything is working perfectly.I talked with Bob and we think the the hose that runs to the bottom of the tank from the unloader may have been sucked into the feed to the machine causing it to trap air in the system. I'll be cutting about 12" off the hose before tonights jobs. Share this post Link to post Share on other sites
Beth n Rod 1,279 Report post Posted March 27, 2007 Jump in anyone and correct me if I am wrong, but if a machine doesn't bypass, and sits idle without the trigger being released...ummm...you can seriously damage the pump? Isn't this a common problem on the little cold units you get at the box stores...you only have so long before you really need to pull the trigger? Beth Share this post Link to post Share on other sites
squirtgun 122 Report post Posted March 27, 2007 From the time I realized there was no pressure until shut down was about 1 1/2 to 2 minutes.I checked out everything this morning and have found no visible damage to the pump head and it's not leaking water.It's still putting out full pressure and the unloader is working fine. It was just a fluke that the hose got sucked into the feed to the machine.It basically created an air lock that was only allowing a bare minimum of water through the system. The instant I realized the pressure had dropped I ran and shut everything down.I believe that is what saved us from having any serious damage. Share this post Link to post Share on other sites
Mike Williamson 198 Report post Posted March 27, 2007 Jump in anyone and correct me if I am wrong, but if a machine doesn't bypass, and sits idle without the trigger being released...ummm...you can seriously damage the pump? Isn't this a common problem on the little cold units you get at the box stores...you only have so long before you really need to pull the trigger? Beth The problem with the portable machines is that they bypass back into themselves, meaning the water in constant circulation from the pump to the unloader and back to the pump gets too hot, and can cause premature failure due to the pump running for extended periods at high temps. What would happen if the machine wasn't bypassing at all, and the trigger gun wasn't released, as that the system would fail almost immediately at the weakest point, likely the pressure hose or a fitting somewhere in the system. I suppose it is possible that the pressure could build to the point where the engine could no longer turn the pump and stalled, but more likely you'd simply blow a hole in something to release the pressure. The only exception would be, as Scott mentioned, is if you have air in the system and aren't really pumping water. Share this post Link to post Share on other sites
PLD 14 Report post Posted March 27, 2007 What would happen if the machine wasn't bypassing at all, and the trigger gun wasn't released, as that the system would fail almost immediately at the weakest point, likely the pressure hose or a fitting somewhere in the system. I suppose it is possible that the pressure could build to the point where the engine could no longer turn the pump and stalled, but more likely you'd simply blow a hole in something to release the pressure. Mike is dead on. Water is incompressible and PW pumps are constant volume pumps. That means that if 1qt of water goes in, 1qt must come out somewhere. There are only three holes to choose from: The nozzle, the bypass hose, or the brand new hole it will create. And we are talking seconds, not minutes. If you have no bypass with the gun closed, either you are sucking air or your pump valves are gone. Share this post Link to post Share on other sites
One Tough Pressure 580 Report post Posted March 28, 2007 What would happen if the machine wasn't bypassing at all, and the trigger gun wasn't released, as that the system would fail almost immediately at the weakest point, likely the pressure hose or a fitting somewhere in the system. Or the high pressure relief valve that some machines come equipped with. Share this post Link to post Share on other sites
Mike Williamson 198 Report post Posted March 28, 2007 Or the high pressure relief valve that some machines come equipped with. Yep! Which wouldn't be a bad idea for those of us who don't have them to install one....may save a hose, or even an injury, one day. Share this post Link to post Share on other sites
squirtgun 122 Report post Posted March 28, 2007 Just to ease everyones mind. I ran the machine this afternoon and watch the hose get pulled across the tank bottom to the machine feed.I re-routed the hose to prevent this from happening again. We cleaned a McD's tonight without incident. Share this post Link to post Share on other sites
PLD 14 Report post Posted March 28, 2007 Just to ease everyones mind.I ran the machine this afternoon and watch the hose get pulled across the tank bottom to the machine feed.I re-routed the hose to prevent this from happening again. We cleaned a McD's tonight without incident. You mean the bypass line got sucked into the intake? Drill a hole in that tank and put a hose barb through the wall. That will never happen again, and you can easily see if the unloader is bypassing by the turbulence in the tank. Just don't let it jet right near the intake or the turbulence can cause air to get sucked in at low water levels. Share this post Link to post Share on other sites
squirtgun 122 Report post Posted March 28, 2007 You mean the bypass line got sucked into the intake? Drill a hole in that tank and put a hose barb through the wall. That will never happen again, and you can easily see if the unloader is bypassing by the turbulence in the tank. Just don't let it jet right near the intake or the turbulence can cause air to get sucked in at low water levels. Yes. There is a hose barb inside the tank.That's where the offending hose is attached.I installed it because the by pass dump directly over the intake and on ocassion it was causing cavitation.I would have never guess the pump would suck the hose across the tank like that. Since re-routing the hose that's inside the tank it shouldn't happen again. Share this post Link to post Share on other sites
FullBlast 14 Report post Posted March 28, 2007 I have mine with the barbed fitting screwed in at the very top of the tank, so the water shoots straight across the take and runs down the far end, away from the feed side. Always something new to learn in this biz!!!!:) Share this post Link to post Share on other sites
Mike Williamson 198 Report post Posted March 28, 2007 I have mine with the barbed fitting screwed in at the very top of the tank, so the water shoots straight across the take and runs down the far end, away from the feed side.Always something new to learn in this biz!!!!:) I just drilled a 3/8" hole in the top of the tank on the opposite side from the intake, and stuck the hose through about 6". It's tight enough that it won't work its way out. Never have any problems!!! Share this post Link to post Share on other sites
One Tough Pressure 580 Report post Posted March 29, 2007 The high pressure relief valves are less than $20.00 and could save you quite a bit on repairs or claims. I also drilled a hole at the tank top and have it shooting across, never had a problem. Share this post Link to post Share on other sites
PLD 14 Report post Posted March 29, 2007 I have mine with the barbed fitting screwed in at the very top of the tank, so the water shoots straight across the take and runs down the far end, away from the feed side. Ditto. Share this post Link to post Share on other sites
PLD 14 Report post Posted March 29, 2007 The high pressure relief valves are less than $20.00 and could save you quite a bit on repairs or claims. I also drilled a hole at the tank top and have it shooting across, never had a problem. Tossed all mine and I've had far fewer problems since. Besides, it's a redundant part. An unloader IS a high pressure relief valve. Share this post Link to post Share on other sites
One Tough Pressure 580 Report post Posted March 29, 2007 And if the unloader fails? Share this post Link to post Share on other sites
