Help with Aireless Sprayer and pressure problem

I'm hoping that potentially some one here may be able to assist me diagnose my loss of pressure on my airless spray paint unit. Currently I am thinking that this is a hydraulic related issue as I just do not seem to have any pressure. The unit is a diaphragm device and from what I can gather uses the hydraulic oil to create pressure on the diaphragm to push out the paint.

My unit is an OldFields 600 EL which i can not find any information on really. It appears to be very similar to the model Seiwa SP-60l and as I understand it was manufactured by Seiwa originally. It seems to be badged by a number of companies as the parts from the list below fit it.

Spraychief- 4500s
Oldfields- EL60/ Super60
Seiwa- S600EL/700GE
Novaspray-Exceed 60
Atomex- GM60E/GM70G/LM70G

The front page of the Seiwa site shows the diaphragm and hydraulic fluid flow creating the pressure under the diaphragm to create pressure to push the material on the other side of the diaphragm out.

My diaphragm is intact, there are no splits and there is no material in my hydraulic fluid.

If I put fluid in the inlet valve without the unit being turned on the fluid sits in the inlet and does not leak out. I''m think that this implies the inlet valve seat is still not worn and functional.

Similar if i manually place fluid over the top of the outlet valve it remains there and does not seep away.

So I am at a loss as to why I have no real suction. If I turn on (outlet valve cover reinstalled) then the fluid on the inlet is sucked into the inlet and sent to the outlet but there is almost no pressure. I can stop the outlet with my finger.

The pressure valve used to make the machine shake a bit when every thing was working but now does not do that so I am thinking it has to be some thing with the hydraulics. The pull of the oil into the diaphragm well is via pressure and i'm thinking there is not enough oil delivered to create the diaphragm pressure. The oil pull is via pressure as well. I've pulled the machine apart and there is nothing blocking the oil inlet to the diaphragm chamber.

So now I am at a loss. Any help appreciated if there is any one here that has any knowledge and has some thoughts. Happy to post detailed photos if that helps. Just looking for idea's. Thanks.

Welcome !!
In my limited experience with repairing airless sprayers, it is most likely clogged with paint somewhere. When finished using these, you need to clean the hell out of them, and then... clean it some more. They save time on painting, but loose it back on the cleaning. I also run antifreeze through it when finished, keeps the internal parts lubed and freeze protected during storage. I suggest remove, disassemble and meticulously clean the entire pump and lightly lube any moving parts. Good Luck!

Do you have the manual? and have you gone through the troubleshooting steps?

https://www.novaspray.com/manuals/SP60E.pdf

You have a bleed valve ("air relief") and a pressure control valve, and an inlet and outlet valve, if any of those four are leaking, you won't have pressure. Those four are far more likely to have a problem because they operate in paint, instead of oil. I think the fact that it moves fluid (volume) shows that the hydraulic side is working, if the hydraulic side was moving fluid very slowly, then the paint pump side would still move fluid very slowly, but would build the SAME pressure (with no leaks).

The manual says to let the pump operate for several minutes to bleed air from the hydraulic side, I'd let it operate with paint or water going through the hose and back to your bucket (no gun or no tip) for several minutes to see if it flushes out on it's own, before pulling apart those valves to inspect.

Welcome to HEF, Tommiy
I replaced a pump in my air less sprayer because it wouldn't pump anything.
Only to find I still had the same problem.
A tiny piece of steel was plugging the nozzle.
I use acetone to flush it when I am done with it.

Hi All,
wow, looks like I came to the right place. Thanks for the exceed manual. I have stripped and cleaned the entire machine from head to toe. There was paint stuck onto the diaphragm and some associated place but not that much really overall. The inlet itself has some rust but this does not appear (remember no expert here) to hinder the valve itself. The outlet is clean and the spring and seat for the ball are intact. It does move fluid but there is simply no force behind it at all. ie. I can stop with my finger.

I am considering that @Delmer may be on the right track but I am not sure because I can not see ways to prove what it is to replace and parts here in AU are extremely expensive for this ie. replace all 4 would be $1000.

The pressure valve is actually on the hydraulic side rather than the fluid side. I'm not convinced that the hydraulics are fully working and that the piston is actually being flooded with enough oil to move the diaphragm. If the pressure valve is faulty then the piston would not get oil to cause the pressure on the oil to move the diaphragm. The picture on the Seiwa site seems to imply that the oil pressure pushes the diaphragm to move via the 4 holes in the bracket underneath it.

I do take the point however that ideally that even if the hydraulics are partially working that the pressure build up should be the same. I can get the relief valve to bleed the system even at low pressure. Again, even here i can place my finger over the end and stop it but it is at the point where all air is removed.

Its like the diaphragm does not move enough to generate pressure. The diaphragm here is quite thick, its not really flexible at all.

The relief valve i think functions as after bleeding the systems if i turn it to closed there is no more fluid that comes out of it.

The pressure valve I've no current thoughts on how to see if its working or if the diaphragm area is actually building up pressure. Any ideas?

It still concerns me that as you say the pressure should be the same irrespective of the diaphragm....but then i have low pressure but seems everything is in tact??

Any further troubleshooting idea's. Some photos below may help?

Thanks all for the input.


Hoping I can get this back to running......

I don't have any help at this point. I'll look at the other site to see how this works exactly. It sounds like the hydraulic pressure is generated on the oil end, and the pressure regulating valve operates on the oil, and each stroke is transferred through the diaphragm. From the troubleshooting it sounds like the oil side is supposed to bleed the air out automatically, which I can't understand how, that air would cause no pressure I'd guess.

What is the history of the problem? have you had this sprayer working for a while? did it happen while spraying? or after storage and it wouldn't start up again correctly?

I've a bit of experience with luwa diaphragm process pumps. The inlet valve is critical. "If I put fluid in the inlet valve without the unit being turned on the fluid sits in the inlet and does not leak out. I think that this implies the inlet valve seat is still not worn and functional." Not so ... You say there's rust. a rust pit will allow back flow at pressure

If the valves are functioning, you have air or a leak in the hydraulic side. it won't build pressure since the pressure piston movement isn't being transmitted to the diaphragm. It's absorbed in the leak or air bubble. Another area was piston seals, if the oil bypasses the piston, no pressure.

Operation at 3000Psi magnifies the tiniest valve leak

Hi all,
Thanks for all the advice. I have got it running and it was the pressure control valve. The original valve must have been faulty because I replaced it with one from a friend and now its back to full on power. Thanks again for the suggestions. If anyone has one of these perhaps the response may assist.

Are you able to disassemble the old pressure control valve? even if it's just to see what's wrong with it, might be fixable if it's not destroyed in the disassembly.

No as far as i can see. I've tried spraying WD40 in it and blowing it out with compressed air. However when i place it back in I get the same low pressure issue. I guess I am up for a new valve but at least I will know its money well spent.

How does the handle come off? that would be the first thing I'd try. most likely it's either chipped or cracked or worn out, but more likely has a piece of debris wedged in there.

Soak it either in enamel reducer or mineral spirits, when that begins to show paint color then blow out with air and see if the regulator resumes working. WD or any other oil won't clean a paint clog.

I run my airless units with mineral spirits to clear after each use, then disassemble and clean small parts and run fresh spirits thru the gun to finish.

The handle comes off via a grub screw. Its pretty clean but I still cleaned it out. There is an odd plastic clip on the valve underneath the know as such. It appears that this is intended to limit outward and inward turns. There is some matching slices on the clip and the inside of the knob. What is strange is that while these do not seem worn at all that they mesh before the valve is completely closed. Its like they miss a turn some how. My valve actually appears quite fine if i operate it with a screw driver! Its some thing to do with the way the plastic clip on works with the knob. If i remove the plastic part thats on the valve the knob closes the valve properly. If I put the plastic part on it does not. Really odd. I think I'll just leave the plastic part off as it seems to operate fine without it. My guess is that its some sort of limiter so you can not completely close the valve....at a guess. I'll go buy a pressure gauge as that is cheaper than the valve.