# Hydraulic pumps and oils



## Chicken lights (Mar 31, 2019)

There seem to be some smart people on here when it comes to oils and hydraulic systems. 

A few years ago the place I was working at lost a hydraulic pump on a machine. They replaced the pump, but, didn’t do a good job installing the lines, and it leaked like a sieve. 

Fast forward a few days, they dumped the old used hydraulic oil in just to keep working

I cringed watching that happen. A lot 

Mentioned this to a friend who’s also pretty  smart with this stuff, a couple years later. He said, if it’s properly filtered, oil change intervals met, correct oil used....basically a hydraulic pump has a limitless life span. He said it’s constantly bathed in oil, which should provide lubrication and cooling, so if it’s properly set up for backlash there should be no wear, essentially. 

I see a lot of you guys talking about changing the oil and keeping stuff clean, I figured this was a good place to ask


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## CalgaryPT (Mar 31, 2019)

When I took a couple of hydraulic courses at SAIT I learned one of the main causes of pump failure is fluid contamination. Eventually all fluid goes bad. But it's especially common in agricultural and heavy equipment applications. The main fluid problem is moisture: it makes your fluid a milky white. It often happens if the fluid gets too hot, then cools down in the tank and captures moisture in the air. Undersized tanks, lack of coolers, moist environments, bad breather caps, etc., can all contribute. Contaminated fluid can lead to pump failures, cavitation, etc.

For someone with maybe an enclosed pump indoors and low cycle time, you should get years and years and years of use. If you are buying something used, I always swap out the oil just in case.


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## Chicken lights (Mar 31, 2019)

CalgaryPT said:


> When I took a couple of hydraulic courses at SAIT I learned one of the main causes of pump failure is fluid contamination. Eventually all fluid goes bad. But it's especially common in agricultural and heavy equipment applications. The main fluid problem is moisture: it makes your fluid a milky white. It often happens if the fluid gets too hot, then cools down in the tank and captures moisture in the air. Undersized tanks, lack of coolers, moist environments, bad breather caps, etc., can all contribute. Contaminated fluid can lead to pump failures, cavitation, etc.
> 
> For someone with maybe an enclosed pump indoors and low cycle time, you should get years and years and years of use. If you are buying something used, I always swap out the oil just in case.


Ok, that makes sense. 

I own a small loader for around the shop. Payed around $1000 for it 7-8 years ago. It’s built in the 60’s. 

Needless to say it doesn’t get much love. 

The gearboxes had so much water in them they froze up two winters ago. 

I started tackling the milky hydraulic oil last year. It’s been parked inside since almost 2017, I’ve been trying to give it some love. Parking it inside and out of the elements is a big step forward.

I found out you can buy water element filters to help filter the hydraulic oil, which is my next step. I’ve drained and filled it twice with clean oil, I’ll drain and fill it again while trying a new water element filter.


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## Alexander (Mar 31, 2019)

I just had a CNC machine overflow its hydraulic tank. This was because so much colant had contaminated the oil. In this case the coolant from the cutting tool was able to get in the non pressure side of the hydraulic cylinder used to clamp the hydraulic chuck. It simply drained back into the hydraulic tank and i had almost 20L of water in the system.  Everything survived  but im still worrying about the pump. Hopefully they bring me a new inline hydraulic filter this week. I didn't want to run the machine with the old filter but that decision was out of ny hands. Here is what the filter looks like. Also attached is a diagram of what happened.


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## Tom Kitta (Apr 2, 2019)

Yeah water gets in... I drained oil from my surface grinder - all 5 gal of the stuff and like 10% plus was... water. It was not even mixed with the oil.


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## Dabbler (Apr 4, 2019)

Some surface grinders have a water separator.  If drained regularly, it helps with the contamination problem.


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## Chicken lights (Jul 14, 2019)

Ok so I started playing with my little tractor again yesterday. Couple questions.

Adding a breather cap to the hydraulic reservoir- good idea or waste of time? I’m thinking it’s not the cause of my problem, but perhaps having a place for air to cycle in and out won’t hurt? 

Adding a fluid level gauge or sight glass somehow- anyone ever attempted to modify a reservoir to add one of these? I did see some reservoir caps have a dipstick, which is great for fluid level, but doesn’t let me see the colour of the oil. 

Anyone ever run rubbing alcohol or similar in oil to try to get rid of water? 

I did screw on a new oil filter that has the water removal element in it yesterday, but apparently from what I’ve been reading that won’t remove a lot of water, it’s not a “fix” to water in the system more so a maintenance type item. If that makes sense


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