Water in Cat Pump 623 Oil

[slash007]

I have 623 Cat Pumps and in one of them the oil is a milky white. I know that means water is mixing with the oil, but I was always told that if water is getting in it is because the intake manifold seals need to be replaced. I changed those out and replaced the oil and it is still milky. Could something else be the cause, or is it possible that I just didn't drain the oil well enough and some of the bad oil was still in there? I though about the oil seals, but it is not leaking any oil so i figured if no oil is coming out, no water should be going in from the seals.

 

[cmawash]

check the 2 little o rings and Teflon back ring on the crome shafts, use silicon o ring lube when siding crome sleeves on so they won't get nicked. water is pushing past o rings.

 

[2Biz]

I have a 310 doing the same thing right now with water getting in the oil. The only way I see for oil to get into the crankcase is through the ceramic plungers. There is an o'ring that seals the bolt that holds the plunger on. Pretty much the same as the 623, although it looks like yours has chromed pistons instead of ceramic plungers like mine. Different design, but same principal. I'm replacing the pump this weekend and will attempt to fix it! My first one! I changed the oil after I discovered the milky oil was above the sight glass. So far its taken about a week for the oil to get just above the center of the sight glass. So its a very slow leak. Its giving me time to get it replaced.

 

[slash007]

I have a 310 doing the same thing right now with water getting in the oil. The only way I see for oil to get into the crankcase is through the ceramic plungers. There is an o'ring that seals the bolt that holds the plunger on. Pretty much the same as the 623, although it looks like yours has chromed pistons instead of ceramic plungers like mine. Different design, but same principal. I'm replacing the pump this weekend and will attempt to fix it! My first one! I changed the oil after I discovered the milky oil was above the sight glass. So far its taken about a week for the oil to get just above the center of the sight glass. So its a very slow leak. Its giving me time to get it replaced.

Mine isn't leaking, just milky. The oil level has been the same for over six months. I did have some of the small o-rings that were damaged, but I replaced those when I changed the oil. I didn't put any lube on the plungers when re-assembling, so maybe I nicked the o-rings again.

 

[pgrzes]

Change the oil seals in the case!! I just redid 5-5cp2120's and a 390. Had the milkshakes did seal kits that didnt work, put new oil seals and things are all good.

 

[MEP001]

Oil seals don't keep water out of the crankcase, they just keep the oil in.

A 623 is a piston pump. The piston rods have sleeves on them with two o-rings and a back-up ring on each one. That's what is bad and letting oil get into the crankcase.

When you work on your 310, there is an o-ring, a back-up ring and a copper washer on each plunger bolt that must be replaced to seal it properly.

If there's water in the oil, it's a good idea to replace the oil seals while you have it apart. The springs on the oil seals rust and will eventually corrode through, then it will leak oil.

 

[mjwalsh]

I changed those out and replaced the oil and it is still milky. Could something else be the cause, or is it possible that I just didn't drain the oil well enough and some of the bad oil was still in there? I though about the oil seals, but it is not leaking any oil so i figured if no oil is coming out, no water should be going in from the seals.

This is a long shot & unlikely ... but be sure & check the vent on the large red fill cap nut & make sure that it is not partially plugged. When we first starting using Cat pumps back in the 70s, the local distributor-installer for them left the tape on over the vent hole & it caused tiny bits of water to seep in the crankcase oil making for a milky appearance.

mike

 

[slash007]

Oil seals don't keep water out of the crankcase, they just keep the oil in.

A 623 is a piston pump. The piston rods have sleeves on them with two o-rings and a back-up ring on each one. That's what is bad and letting oil get into the crankcase.

When you work on your 310, there is an o-ring, a back-up ring and a copper washer on each plunger bolt that must be replaced to seal it properly.

If there's water in the oil, it's a good idea to replace the oil seals while you have it apart. The springs on the oil seals rust and will eventually corrode through, then it will leak oil.

That's what I thought. I replaced the small o rings on two of the pistons, the third seemed good so I left it. I also didn't use any grease, so maybe I nicked them putting the sleeve on. If so, it would be the interior o ring. I drained it for a while, but I am sure there was still a small amount of the old watery oil left inside. Would a little bit of the milky oil possibly cause the new oil to be milky?

 

[Stuart]

I have cat 530's. When I get oil in the crank case, after I fix the cause, I drain the crankcase and over fill it with kerosene. I manually hit the motor contactor 3-4 times for about 4 seconds each. Drain the case and repeat one more time. Drain case and fill with oil to top of red dot. This usually works for me.
The cause of water has been plunger seals, or water spraying on top of pump and getting in the fill cap.
Hope this helps

 

[MEP001]

That's what I thought. I replaced the small o rings on two of the pistons, the third seemed good so I left it. I also didn't use any grease, so maybe I nicked them putting the sleeve on. If so, it would be the interior o ring. I drained it for a while, but I am sure there was still a small amount of the old watery oil left inside. Would a little bit of the milky oil possibly cause the new oil to be milky?

It might. I mix three parts ND-30WT oil and one part transmission fluid and run that in the pump for a week. It will pick up the remaining water. Just changing it two or three times with Cat oil will too, but the mix will do it in one shot.

 

[cmawash]

take a close look at the crome sleeves in the sun lite if there are any scratches on the sleeves throw them away scratches will led to suction problems & damage the inlet seals and don't skimp on the little O-rings.ok to reuse Teflon back up rings if not bent. it is a lot cheaper to it right the first time then have do it a second time have close to 40 623 pumps in service. great pump just over it correctly and you wont have to look at again for several years. there sound is money being made

 

[Ghetto Wash]

On the 623 pumps, is there an easier way to replace the oil seals other than taking the whole crank case apart?

 

[slash007]

On the 623 pumps, is there an easier way to replace the oil seals other than taking the whole crank case apart?

Not really, you have to remove basically every part in front of them to get to the seals. I hate doing it, but it really doesn't take that long once you've done it a couple of times.

 

[MEP001]

You can pry out the oil seals, but you need to be very careful not to score the pistons. The smallest scratch will make it leak oil.