What's with these unloaders?

[I.B. Washincars]

Recently I developed a leak at one of my remaining Cat 5CP-2120 pumps. Water was coming out of the hole in the Suttner unloader. When it finally got bad enough I decided to swap it out. All was well for about a month and then the new one started leaking. I also felt a slight pulsation in the pump so I yanked it apart and found a pitted valve disc and one LP seal with a small nick. When I realized I didn't have a seal kit I decided to just go ahead and install the Arimitsu that I eventually planned to install anyway. I put the pump on with another new unloader and all was well at the wash again. That was two weeks ago, today I notice the second new unloader is leaking just as the two before it. Any idea as to why all of these unloaders would leak? Pics of both pump set-ups are below.

Cat

Arimitsu

The shot of the Arimitsu is a little deceiving. That tee with the guage and check valve is screwed into a port in the head. The angle of my shot makes it look like it is screwed into the unloader.

 

[MEP001]

I'd have to guess you got a bad batch of the Suttner bypass regulators (Not an "unloader" for accuracy's sake). I've never used them myself, but I've seen them 20 years old and working perfectly.

I like Paraplate - they tend to last 5-10 years, except on the big Cat 390 spot-free pump where they last only one year because of the volume going through it. I never have to worry that low pressure is a regulator problem, I just replace it when it starts to leak.

 

[JGinther]

Does cleaning out the seat temporarily fix it? If it does, you may have an unrelated problem upstream of the pump that is allowing foreign material to jack up your pump seals, valves, and regulator seat. If not, its probably just another case of bad QC. It seems most companies now are eliminating QC now due to the high cost. Thank you beancounters.

 

[jcedwards]

I.B., I'd be careful with the Suttner regulators. These valves have a swedged ball in piston design. The ball can fall out, lock-up and blow up something. Also, this valve uses a fat o-ring and backing ring. The constant operation will where this out. These valves were designed as temporary blow-off valves, not day-to-day regulators.
I would look at the Pumptec 510 valve available from Arimitsu. It looks similar, but the insides feature a 1 pc piston and a u-cup that will work better for slight movements, like a piston cup.

 

[I.B. Washincars]

These Suttners were original to the Magic Wand equipment at this wash, built in '95. I have owned it since '01 and have had very little trouble with them until now. I didn't try cleaning anything out. I actually took the first new one apart and found a bad o-ring. I found nothing in the Cat when I disassembled it other than the small defect in the LP seal. I called Greg at Arimitsu yesterday to see if he had any ideas and he felt the same as you guys, not a pump problem, but a regulator problem. I needed a spare pump to put back on the shelf and also ordered one of their regulators as well.