CAT 3535 loses prime

[Waxman]

After sitting idle my 3535 will chatter briefly on startup. It seems it is losing its prime somehow.

Where do I start looking?

 

[MEP001]

It won't lose prime on its own. Something is likely pushing air through the pump from the bay. You may have a bad bypass regulator or trash in a pump valve.

 

[Waxman]

So if my screen on the inlet in the feed tank were scuzzy it wouldn't lose prime, or if there were debris in the feed tank?

The filter screen is a bit dirty. Bottom of feed tank not too bad.

Thanks!

 

[Bill Manke]

From the tank to your pump. What is there? A flexible line Plastic or Brass fittings, Hose clamps,any inlet for soap , wax or air? If no air I would look for a cracked fitting, loose clamp, cracked hose. If air I would look for a leaking air solenoid that is leaking air into the inlet really slow.

 

[Whale of a Wash]

Probably not air-if you have gravity feed there would be a leak. Maybe a solenoid isn't opening quick enough to let water flow when pump starts.

 

[pitzerwm]

The stuff preventing enough water to get to the pump could cause that.

 

[MEP001]

I don't know enough about your set-up, but usually the pump is flooded by the holding tank above it, and it's rare to have any sort of valve controlling flow to the pump. In that sort of system the pump can't just lose prime for no reason. It can be difficult to tell whether the pump is cavitating from lack of supply or clattering from air in the lines. Can you describe the plumbing in detail and post some pictures with it?

 

[Waxman]

Holding tank above pump feeds water directly in. There is a bypass w/solenoid for medium pressure wax and another for underbody flush. There is an unloader plumbed in as well. That's the only plumbing associated w/3535 out to bay. All other soaps/polish are applied w/ dayton l.p. pump and that plumbing is separate.

I did douche the tank out well this a.m. as well as removed the filter screen and cleaned it. It was pretty gunked up and so far so good. But I will know better tomorrow morning, as that is when I have noticed the problem.

Thank you!

 

[madscientist]

If your medium pressure wax product line is drawing air you would get the chatter. I'd suspect the unloader though. Is there a check valve past the unloader that keeps other (low pressure) products from running backwards into this line? Or does the unloader serve that purpose?

 

[Jud]

This problem sounds like one I went through a short time back. Several months I fought falling flow and pressure, checked everthing mentioned here at least twice, plus items not mentioned. My problem turned out to be wash out under the intake valve seats. Remove your valve seats to inspect for this. This is a very easy item to overlook. Bad news is that if you are looking at replacing the manafold with thr valve seats, you may as well look at buying a new pump. However to me, the good news is that my seemingly perpetual problem is fixed. Jud

 

[Waxman]

It wasn't that. The problem was a bad check valve on the soap delivery manifold inside my gantry. It has been fixed for awhile now.