CAT 2120 Maintenance

[stampedecarwash]

Hello, I though I can find something here easy and clean like a check list of items we need to do to make sure our pumps stay in a good shape, but wasn't successful. I have 5 of these CAT 2120 pumps. Every now and then I see the pressure fluctuate so we change the little rubber washer on the valve, or the entire valve. IF there is a leak we change the lowpressure seal. Of course change the oil every 3 month... is there anything else we need to do? Why people are so worried about washed our heads? why is that happening? Thanks

 

[Greg]

Hi Stampede & Guests, Happy to help !
Best thing you can do for any plunger pump is to give it a good water supply.
Plunger pumps are positive displacement, so give them plenty of water at the inlet - refrain from starving them too much.
Change your high pressure seals at the same time you change the low pressure seals.

My thinking is washout happens when 2 ingredients are simultaneously present;
a) Pump is starved of water.
b) Bypass from the pressure regulator is plumbed back to the pump inlet.

Bypass water is turbulent by nature, it goes from a pressurized condition within the regulator to an unpressurized or possibly a vacuum condition within the bypass hose when plumbed to the pump inlet.
The turbulent bypass water has little to no chance of escaping the pump head while the pump is starved of water, leaving only the turbulent water to remain in circulation while at the same time the pump continues to draw in more air if being starved of water.

By comparison, Plunger pumps are also used for pressure washers where the bypass is also commonly plumbed to the pump inlet - however those pumps are commonly pressure fed with a garden hose.
No washout in that industry that I am aware of.

Also by comparison, the same plunger pumps are used in pumping stations for prep guns.
No washout there as those systems are commonly gravity feed and also do not require bypass plumbed back to the pump inlet.

Give pump adequate water supply and you will be good for a long time.

Happy to help !
Greg Thoennes , Sales & Tech. Support
Arimitsu Pumps
763-205-8341

 

[MEP001]

The main reason I've found for washed out Cat manifolds is the flow through the pump. A lot of washes I've seen have the inlet and outlet on the left side and the regulator and bypass return on the right, which means every time the trigger is pulled or released there's a brief cavitation as the water changes direction. Replumbing the pumps tends to triple manifold life at these locations.

Cat recommends changing the oil every six months. Most people never change the oil at all and never have a problem that isn't related to water in the oil, but I wouldn't suggest that.

It sounds like you're already taking good care of your pumps since you change valve o-rings at the first sign of a pressure loss. The other thing that really kills the manifolds is letting them run for months with a bad seal.

 

[Car_Wash_Guy]

Cat recommends changing the oil every six months. Most people never change the oil at all and never have a problem that isn't related to water in the oil, but I wouldn't suggest that.

I literally just changed my oil after 3 years. Looked as clean as the oil coming out.

 

[stampedecarwash]

The other thing that really kills the manifolds is letting them run for months with a bad seal.

thank you, how do I know if I have a bad HIGH PRESSURE seal? I change the low pressure one when it starts leaking, but how do we know if the high pressure one needs to be changed? loosing pressure perhaps? but that could also be due to high pressure valves. Vibrations is due to bad valves.

 

[stampedecarwash]

I literally just changed my oil after 3 years. Looked as clean as the oil coming out.

mine looks really milky after 1-2 month...

 

[MEP001]

You'll start to lose pressure when the high pressure seals are going, but here's the real problem: a lot of equipment is set up with the pump turning a lot faster than it needs to, in some cases a whole gallon per minute always being bypassed through the regulator under normal operation. When the seals start to go, that extra flow goes around them until there's a loss in pressure. That's how most manifolds are ruined, an entire gallon of water per minute squeezing past the seals. I've seen 5CP6120 pumps running 1500 RPM with 3 GPM tips, which means 3 GPM being pumped over the tip can flow. When their manifolds go bad, even Dynajet can't fix them.

Milky oil isn't unusual if your room is really humid, but you certainly aren't hurting anything changing the oil more often because of it.

You could replace seals on a routine basis or after a certain number of hours just to be safe.

 

[Greg Pack]

I literally just changed my oil after 3 years. Looked as clean as the oil coming out.

What- there's oil in those pumps- and I'm supposed to change it?

 

[I.B. Washincars]

Ok, I'm gonna fess up. Many of you know that nearly all of my pumps are Arimitsu, primarily the 516. Just before July 4th weekend I noticed one of them was making a funny squeaking sound, like nothing I had ever heard before. When the customer finished I blocked the bay so I could check it out. When I tried to turn the pulley by hand it was seized and wouldn't move. I removed the belt and determined that the pump was locked up. I removed the oil cap to be greeted by smoke exiting the hole. I knew that either I had a dead pump or a new pope, not really sure. Judging from the date of install on the sticker I had put on, apparently 10 years is the limit for not checking or changing the oil, YMMV. I needed this pump to live through the holiday weekend so I could get Greg to ship me a pump and get it installed the next week. Sitting on my workbench was a gallon jug containing about 2" of air compressor oil. I dumped that in there, stuck a crow bar through the pulley spokes and actually got it broken loose. I turned it by hand for a bit and it actually freed up somewhat. I stuck the belt back on and crossed my fingers. Whad'ya know, it worked. It lived long enough for the new pump to arrive. Since it was working and sounding just fine, I just put the pump on the shelf and would just install it after the pump grenades. Well, the pump is still working just fine and the new one still on the shelf...who knew.

Oh, and this little tidbit. I referenced July 4th weekend. It wasn't this past July 4th. It was 2015! That pump is still running after three+ years!!! And it's not installed on some obscure bay on the back 40 that's seldom used, but on my busiest bay at my busiest wash.

Oh BTW, its still got that air compressor oil in it.

 

[stampedecarwash]

Oh BTW, its still got that air compressor oil in it.

Thanks for sharing the story, I didn't know compressors use different oil than pumps. I got a DV System DEV-55 compressor, what oil do you recommend?

 

[MEP001]

Thanks for sharing the story, I didn't know compressors use different oil than pumps. I got a DV System DEV-55 compressor, what oil do you recommend?

I'd recommend air compressor oil, but you can most likely get by with ND-30W. I use synthetic compressor oil in compressors since it's fairly cheap and I almost never change it.

 

[I.B. Washincars]

what oil do you recommend?

With my track record. I think you should ask someone else .

 

[MEP001]

Ok, I'm gonna fess up. Many of you know that nearly all of my pumps are Arimitsu, primarily the 516. Just before July 4th weekend I noticed one of them was making a funny squeaking sound, like nothing I had ever heard before. When the customer finished I blocked the bay so I could check it out. When I tried to turn the pulley by hand it was seized and wouldn't move. I removed the belt and determined that the pump was locked up. I removed the oil cap to be greeted by smoke exiting the hole. I knew that either I had a dead pump or a new pope, not really sure. Judging from the date of install on the sticker I had put on, apparently 10 years is the limit for not checking or changing the oil, YMMV. I needed this pump to live through the holiday weekend so I could get Greg to ship me a pump and get it installed the next week. Sitting on my workbench was a gallon jug containing about 2" of air compressor oil. I dumped that in there, stuck a crow bar through the pulley spokes and actually got it broken loose. I turned it by hand for a bit and it actually freed up somewhat. I stuck the belt back on and crossed my fingers. Whad'ya know, it worked. It lived long enough for the new pump to arrive. Since it was working and sounding just fine, I just put the pump on the shelf and would just install it after the pump grenades. Well, the pump is still working just fine and the new one still on the shelf...who knew.

Oh, and this little tidbit. I referenced July 4th weekend. It wasn't this past July 4th. It was 2015! That pump is still running after three+ years!!! And it's not installed on some obscure bay on the back 40 that's seldom used, but on my busiest bay at my busiest wash.

Oh BTW, its still got that air compressor oil in it.

It's a bit expensive and time-consuming to repair, but assuming Arimitsu has a hardened steel shaft you can replace the connecting rods (and bearings if they feel rough) and it will be as good as new. I've often had to sand aluminum melted onto the crankshaft from the connecting rods from a pump being run without oil.

 

[I.B. Washincars]

I've often had to sand aluminum melted onto the crankshaft from the connecting rods from a pump being run without oil.

Yeah, I spent a couple of decades in the lawn and garden equipment business. Have saved several small engines this way. I think it's pretty obvious that I'm not going to bother the crankcase on this pump. I actually put seals in the head last year, just counting on it running forever.

 

[stampedecarwash]

I'd recommend air compressor oil, but you can most likely get by with ND-30W. I use synthetic compressor oil in compressors since it's fairly cheap and I almost never change it.

Good point actually, do I need to change the compressor oil at all? It looks pretty clean....

 

[Randy]

Good point actually, do I need to change the compressor oil at all? It looks pretty clean....

No you don't need to change the oil in your air compressor. Just check the oil level periodically. I put my oldest air compressor in service in 1992 and it's still in service today. I've never changed the oil, just check it periodically, I think I've added about a cup of oil since I put it service. I also don't change the oil in my Cat pumps either, unless they are full of water I'll change the oil.

 

[Main Street Carwash]

Just an FYI, muratic acid will clean aluminum off the crankshaft without hurting it. It is done by engine rebuilders often to remove aluminum from cylinder walls and such. Much less labor than sanding and no chance of damaging the journals on the crank.