Cat Pumps 623 crank bearing making noise

[Rudy]

I've got a Cat Pump 623 that's making some noise. When I use a stick to "listen" to various parts of the pump, it appears that the noise is coming from the crankshaft bearing.....the side that the pulley attaches to.

Over the years, I've done cups, valves, blue dots etc. But....I've never done anything in the crankcase except change the oil yearly with 30wt ND.

What's involved with replacing the bearing? Can it be pulled from the outside and replaced?

This pump doesn't owe me a dime. It's 23 years old....and until now....has purred like a kitten.

Advice?

 

[MEP001]

It's not an easy job but it can be done with hand tools. You'll have to remove the pump, remove the back cover, pull the connecting rod end caps off (and keep them in order, they must go back on exactly how they came off), pull both the bearing covers and you can work the shaft out. You'll need to drive the old bearing off and drive the new one on without damaging it or the shaft - I've used a piece of heavy C-channel aluminum to drive it by the inner race, and of course you'll need to rest the shaft end on a piece of wood or something that won't damage it. Reassembly is pretty straightforward, you must put the shaft back in the way it was oriented, and it would be a good idea to replace the shaft oil seals while you're in there.

 

[Randy]

It might be time to invest in a new pump.

 

[Rudy]

How tightly are the bearings pressed onto the crankshaft? I'd assume not too much.....because...I don't know how you'd remove the crankshaft from the case if the bearings were really tight......

Asked another way....once the bearing caps are off (and connecting rods removed from the crank).....would you be able to remove the crankshaft simply by placing a 2x4 over the end of one of the exposed shaft ends....and hammering the 2x4?

Randy...you're also right. Sometimes it's time to take out your checkbook....and just pay. Do you (a) Pay $1200 for a new pump (b)Pay $500 for a used pump (c) Spend a couple of hours and throw $70 worth of parts into a 20+ year old pump....that still seems OK otherwise?

Not sure yet......

 

[Rudy]

Quick add on question....

Anybody replace the Cat 623 with an Arimitsu? Which model 508?

All I know is that they are supposed to be quieter.

What would be needed? Different rails? Pulley?

 

[slash007]

I have 6 cat 623 pumps that have been running for 20+years. I have replaced the bearings in a few of them. It's been a couple of years since the last one so I don't remember much about it, but I know it wasn't too hard. We using a tool to put take the pulley off as that was the hardest part, but replacing the bearing and oil seals wasn't bad. I am actually replacing my whole pump stand and will have 6 cat 623 pumps along with some extra new bearings for sale soon if you are interested. Just waiting for a rainy week in order to shut down and do the switch. I actually also have a 7th 623 I bought as a backup but never used. It is the body only.

 

[MEP001]

How tightly are the bearings pressed onto the crankshaft? I'd assume not too much.....because...I don't know how you'd remove the crankshaft from the case if the bearings were really tight......

They're pretty tight. It takes some work to get them off. I don't know if they're heated to expand or pressed on, and they weren't meant to be driven off and on but it can be done, I've done it quite a few times.

Asked another way....once the bearing caps are off (and connecting rods removed from the crank).....would you be able to remove the crankshaft simply by placing a 2x4 over the end of one of the exposed shaft ends....and hammering the 2x4?

That's something I don't remember, it's been a very long time since I've had one apart. Some you can just remove the rod ends, the side covers and just slide the shaft out, some you have to drive the side covers off the bearings.

Do you (a) Pay $1200 for a new pump (b)Pay $500 for a used pump (c) Spend a couple of hours and throw $70 worth of parts into a 20+ year old pump....that still seems OK otherwise?

I'd do the $70 repair, but that's because I have the experience to do it, plus I kind of enjoy stuff like that. I would NOT spend $1200 on another 623 when you can get an Arimitsu for $700 and have the capacity for more pressure and have a more reliable and easier to service pump. Actually I'd go with a Cat 5CP2120WS (Sleeved head, will never wash out).

Anybody replace the Cat 623 with an Arimitsu? Which model 508?

All I know is that they are supposed to be quieter.

What would be needed? Different rails? Pulley?

508 would be the logical choice IMO, the smaller 313 is rated about the same max pressure as the 623 and plenty of flow but would be running hard. Yes, you'd need different rails and pulleys.

 

[slash007]

Isn't the 623 a suction feed pump while the 508 and 5cp pumps are gravity feed?

 

[MEP001]

The 623 can handle a good bit of suction lift, Cat plunger pumps can't, some plunger pumps can but not like a 623. Don't know about Arimitsu.

 

[Ghetto Wash]

Asked another way....once the bearing caps are off (and connecting rods removed from the crank).....would you be able to remove the crankshaft simply by placing a 2x4 over the end of one of the exposed shaft ends....and hammering the 2x4?

Yes, but it will only go one way and one of the bearings will come out with it. When you take the back plate off the gear box you will see an arrow stamped into the inside of the case. You have a 50/50 shot - I don't remember if the arrow points in the direction to put the crank in or take it out.

 

[Greg]

Hi Rudy, Yes repair can be done and it appears you have good resources here for spare parts.
I see you also asked about model 508, additionally models 511, 516, & 313 are common.
It will be ideal to know the following when selecting a new pump;
* Application; single gun, dual gun, or other ?
* PSI you like to spray ?
* Nozzle size you use ?
* Existing pulley diameters on the motor and pump ?
(depending on the pump, you may be able to use the same pulleys, but a new bushing will be needed for the pump shaft)

Helpful video resources here; http://arimitsupumps.com/html/arimitsu-pump-repair-video.php
* Click "Technical Tips"

Happy to help !
Greg @ Arimitsu Pumps

 

[Rudy]

The rebuild is done....and I thought I'd pass along a few comments...

I found the arrows stamped on the inside of the crankcase. It's visible when the rear cover is removed. The arrows DO NOT show the direction to remove the crankshaft. From the rear, the arrows point left. The crankshaft has to be driven to the right (Anti arrows) and then about 2/3's of the crankshaft is hanging out the right side. I used a 3 jaws gear puller, and pulled the exposed bearing. The crankshaft has to then be reinserted and driven all the way to the left (arrow direction) and removed. The remaining bearing was then pulled with the same gear puller.

Reinstall is simply the reverse. I had some old plumbing fittings (and 1" pipe) that allowed me to make a shaft driver so that the inner race could be driven onto the crankshaft.

Someone mentioned to replace the "oil seals" while it was apart. I ordered CRANKSHAFT oil seals....but failed to notice that there are 3 CRANKCASE oil seals. They look bad, and will have to be replaced later after I get the parts.

Can the crankcase seals be pulled from the outside?

I replaced the blue dot seals, and also the sleeves. It isn't that bad of a job to pull the manifold to gain access to the sleeves again. My question.....how can the crankcase seals be removed? Can they be pulled from the outside after removing the sleeves? On other projects, I've sometimes been able to remove seals by drilling a small hole in the seal, inserting a long self tapping screw, and pulling it out. Any advice?

 

[MEP001]

IIRC the screw trick will work to pull the piston oil seals.

 

[Fatboy769]

IIRC the screw trick will work to pull the piston oil seals.

Mep001 that is correct. Removed several oil seals that way.