Pump losing pressure cannot regulate


Randy Dockins
Premium VIP
Nov 12, 2008
Real Name
Randy Dockins
Business Location
United States
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.
There's still things about this machine I doubt I'll ever really understand. I'm terrible with anything electrical and as you probably guessed not too good with unloaders either! I do know more than I used too though! I'll tell you one other thing I advise is NEVER to leave your old part to be tossed unless you're absolutely certain you can never use it again. I wished I'd kept my old unloader. I would've gotten from point A to point B a whole lot faster! The very first words out of my mouth when they told me my pump was losing pressure and I needed a new pump installed was, "Do you think the unloader could be the problem?" I wished I'd listened to my gut. I knew my pump worked fine when I took it in there.


Well-Known Member
Nov 29, 2013
Real Name
Marian Lukacisin
Business Location
United States
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.
I share your pain.I had to buy from Jon Don complete pressure regulator despite the fact that I needed only $8( at that time) part. The bullet( piston) got worn out to the point that needed to be replaced. I called first making sure that part is available. They assured me that part will be waiting for me on arrival. Well, $8 turned in $79.99. Similar situation happened to me more than once, so I stopped visiting them altogether. Works great for both parties. I've learned to have a back up parts on hand ( ordering online from different suppliers) and fix the issues myself.
As @Jim Davisson mentioned , lint and microscopic debris on check valves can cause trouble with the pressure. I've learned that with my General Triplex pump (1200 psi). After a while I didn't let that suprise me by maintaining the pump. Once in a while, I would disassemble the pump, soak check valves in vinegar, inspect springs, drained all the water, applied thin layer of lubricant on o rings to prevent cracks and most importantly not overtighten the screws once maintenance was done. Fresh ISO 68 took care of the ceramic plungers and pump is working just fine with all original parts after almost 8 years. That's what TLC can do for you, but yeah, sometimes you got to spend money regardless .
Good old Prospector....
I got rid of portables
( all 4 of them), but one.
Again, @ Jim Davisson is the man!!!
I smelled the rat, when you mentioned that you were losing pressure after Jon Don mechanics put hands on it, but never suspected pressure regulator. Good story. We learn every day....