Pump losing pressure cannot regulate

[wandwizard]

This is a new one on me. I'm trying to figure out what's going on with my Comet pump. I took the machine into https://shop.truckmountforums.com Monday and had them work on a few annoyances and the pump was working fine when I took the machine there. They told me after they worked on it that it was losing pressure and needed another 800 bucks to put a brand new pump on. This pump is only about 1-year old installed 5/14/18. What is happening is I can set the pressure to say 500 psi and stand in front of the machine and begin to trigger the wand. As I'm triggering the pressure will continuously drop incrementally. As it runs more you begin to lose the ability to adjust the pressure with the unloader to say more than 300 psi. Where I'm setting it for 300 psi it should be easily over 1,000 psi. Yesterday as I used the machine I had to keep adjusting the pressure just to finish the job and sometimes the pressure would spike and bury the needle to 1,500 psi. At this point I'm pretty sure I have some damaged seals, probably the high-pressure ones. The pump doesn't pulsate and I am pretty sure there are no obstructions in the line or inside the pump. I think the seals may have been damaged due to the fresh water pump going out and not feeding the machines' tank. I think it was bottoming out. Any advice would be appreciated.

 

[Jim Davisson]

I would inspect the valves before I went any further. Are they accessible enough to check quickly?

 

[wandwizard]

I would inspect the valves before I went any further. Are they accessible enough to check quickly?

I think I can access them w/o removing the pump head. I was just told by https://shop.truckmountforums.com service they think it's the check valves causing the pressure loss. It is not leaking any water and no pulsation. I do have a brand new set of check valves and O-rings on hand and I think I'm gonna go ahead and remove the old ones and see if it tells me anything. I was thinking perhaps the high pressure seal or seals were bad since the problem only occurs under pressure. Jason at https://shop.truckmountforums.com told me the check valves are what allows the pump to build and maintain pressure. I didn't know that. I did a bucket test and the pump puts out the full 3.5 gpm when it's not under pressure. When under pressure there is a gradual drop and after it gets hot I can hardly get any pressure at all. I'll be pleasantly surprised if it's just the check valves, but I'm not hopeful that will fix it.

 

[Jim Davisson]

Sounds to me like a pressure side valve(s) has a piece of debris or is slightly deformed and not seating right. Low pressure and then the sudden spike is what has me leaning towards valves. Hopefully it is an easy fix.

 

[wandwizard]

Sounds to me like a pressure side valve(s) has a piece of debris or is slightly deformed and not seating right. Low pressure and then the sudden spike is what has me leaning towards valves. Hopefully it is an easy fix.

I think I found the problem, but don't know if I can fix it myself. I took the entire pump head off and it looks like one of the plungers or whatever you call it was stuck. I'm trying to replace the seals in it, but have run into a problem. One of the seals goes on the inside of another part and I can't for the life of me figure out how to put it in there. The part is closed at both ends and the seal fits inside it.

 

[Jim Davisson]

Patience, lube, persistence and bad words is what it takes to load those washers inside the cup. You can buy them "loaded" already for $30-$50 more and it's worth it sometimes. I drop the seals in a hot cup of water and get them very malleable and then I can push him inside there pretty easy and when I say pretty easy I'm being very loose with that lol

 

[Jim Davisson]

Every pump I've done that to, the washers go in a certain way. Look at an old one to rebuild a new one to make sure you get the attitude of the washer right.

 

[Jim Davisson]

If you think you are going to break the seal forcing it in there, you are doing it right lol

 

[wandwizard]

Patience, lube, persistence and bad words is what it takes to load those washers inside the cup. You can buy them "loaded" already for $30-$50 more and it's worth it sometimes. I drop the seals in a hot cup of water and get them very malleable and then I can push him inside there pretty easy and when I say pretty easy I'm being very loose with that lol

Well, I got em in there after watching a video. Fortunately, this video was on a Comet pump that's kind of like mine. I put those low-pressure seals inside there just like he showed and once they're inside I just worked them around with my finger and they popped into place. I now have it all back together and tested it out a while and it's working. It seems to be holding pressure like it's supposed to and I can adjust it normally. I didn't even use any bad words either. This was pretty frustrating though. I was intimidated to put those seals in, but it was actually easier than I imagined. That one seal was a little tricky though. This video helped a lot. I changed all the check valves and O-rings too, but I really think all of those were ok. I was thinking since this was only happening while the pump was under pressure and that the bucket test showed accurate that it must be the seals. I was hoping just the check valves would do the trick, but that didn't help at all. At least I've got a complete set of good check valves though!

 

[wandwizard]

I'm gonna tell on myself. I've actually bought an entire new pump more than once rather than try to change out those seals. Now part of the reason for that is I never was able to get a good price on the seals and check valves. It was over 1/2 the cost of a new pump. They were so high that it made better sense to me to buy a whole new pump. I have at least 2 more pumps that I could fix with new seals and check valves. Since doing this I have a little more confidence to tackle them.

 

[Jim Davisson]

Glad you got it up and running! Pretty soon you you will have a couple pumps rebuilt and on the shelf ready to just drop in at a moment's notice, and that's a good feeling!

 

[Ara Klujian]

I'm gonna tell on myself. I've actually bought an entire new pump more than once rather than try to change out those seals. Now part of the reason for that is I never was able to get a good price on the seals and check valves. It was over 1/2 the cost of a new pump. They were so high that it made better sense to me to buy a whole new pump. I have at least 2 more pumps that I could fix with new seals and check valves. Since doing this I have a little more confidence to tackle them.

Glad you got it fixed! It's a good idea to have a spare pump and you can sell one.

 

[wandwizard]

Glad you got it fixed! It's a good idea to have a spare pump and you can sell one.

If I go ahead and fix the 2 I have in my garage I'll have 2 spare pumps!

 

[wandwizard]

Well, my victory was very short lived. When I tested the pump out yesterday all seemed to be well, but when I went to use it today I barely got started before it lost almost all pressure. Fortunately I wasn't far from home so I went and grabbed my Prospector portable and worked with that today and looks like tomorrow as well. It's a good thing I already placed an order for a new pump just in case. I may fool around with the other two I have and see if I can get one to work in the meantime. Good thing I have a portable for backup. I rarely use it otherwise.

 

[Jim Davisson]

Well, my victory was very short lived. When I tested the pump out yesterday all seemed to be well, but when I went to use it today I barely got started before it lost almost all pressure. Fortunately I wasn't far from home so I went and grabbed my Prospector portable and worked with that today and looks like tomorrow as well. It's a good thing I already placed an order for a new pump just in case. I may fool around with the other two I have and see if I can get one to work in the meantime. Good thing I have a portable for backup. I rarely use it otherwise.

Bittersweet victory yesterday... I would replace the valves and washers inside with the new ones on hand straight away.

Why? Because you have a wet end issue and the hydraulic end has no influence on this performance issue.... You have 2 other pumps to cherry pick parts from without buying a thing. These issues are trying, but with as many parts as you have in triplicate you have nothing to sweat but time and patience.... but I'm a stubborn bastard and HAVE TO KNOW the why and how for everything because no one else will do it for you.

 

[EuroPad]

Did the new pump fix the problem. I got a new pump, but am still losing pressure.

 

[wandwizard]

Did the new pump fix the problem. I got a new pump, but am still losing pressure.

I am really a little embarrassed to say what my problem actually was, but it turned out to be because I had a new unloader put on my Boxxer at https://shop.truckmountforums.com. Now, I thought those guys knew what they were doing, but it turned out on this particular thing they didn't and it caused me some real problems. I bought a new unloader that is the exact same one as Hydramster uses on my machine. I didn't know that they remove something from it for it to work. I've only had two unloaders on the machine since 2002 so I knew virtually nothing about them. When my first one went out it began losing pressure and eventually lost all pressure one day. I still have no clue exactly what happened. At first it was difficult to adjust pressure and finally, I had no pressure at all.

I'd say if you have put a new pump on and still lose pressure I'd look at your unloader, especially if you're losing a lot of pressure. It might help to say what kind of machine you have. Are you losing almost all your pressure or just some of it?

 

[Jim Davisson]

You had your issue because Jon Don didn't convert your unloader into a balanced pressure regulator right?

 

[wandwizard]

You had your issue because Jon Don didn't convert your unloader into a balanced pressurepr regulator right?

Exactly right! Thing is I didn't know that at the time. All I knew was I had a brand new unloader installed by https://shop.truckmountforums.com and all of the sudden I'm losing pressure. They were trying to get me to spend another 800 bucks for a whole new pump. I should've put 2 & 2 together but I was stimied and didn't know what to make of it. All the mess I went through with the pump was because I, and evidently they, didn't know to take that check valve and spring out which takes all of 2 minutes. Oh well, live and learn right? This really goes back to the issue of being forced to buy parts for my machine that has to come through Hydramaster at 4 to 5 X retail.

 

[Jim Davisson]

The best part is that you honestly shared your experience here and you will likely save many others the trouble you went through even though you paid professionals to do the work.

Some here think veterans of the industry don't make mistakes because they've been doing it for so long. Truth is we just had to learn the hard way before the internet put a 10¢ professor in everyone's pocket.