PC60-2 hydraulic oil change

[digdig]

I need to change the hydraulic oil in my recently purchased Komatsu PC60-2 (year approx 1984). I'm going with SAE 10W as per the manual, a local supplier was saying that cheaper hydraulic 46 would be fine, any thoughts? I'll go with 10W unless I hear different, but it's about €60 for a fill more expensive.

Also when changing the oil what do I need to look out for? Do I need to siphon out the old oil and just add the new oil and put in new filters, or disconnect a hose leading from the bottom of the tank and drain from there? I there a danger of air-locking somewhere?

The old hydraulic oil doesn't look right to me, kinda milky, could that be water mixing in, or is it fairly normal for oil that may not have been changed in a long while? See pic below.

 

[707]

That is way too milky. You need to flush your system if the rest of the oil in the tank looks like whats in the picture, probably have some corrosion inside your tank aswell. Position the machine so where you can retract most of the cylinders in. This usually for an excavator is stick out, bucket all the way out, boom down and blade up. Doing this will return as much of the oil back to tank. Pull the plug off the bottom but be sure you have a suitable container to handle 50L or so. You should not really be mixing viscosities, your pump may not like it and it could possibly hinder performance. Also you should change your filters and that o-ring in your picture looks no good either. once you have new fluid put in you can bleed the pump via the bleeder screw on top of the pump, not quite sure on the exact location but there definitely will be one on top of your pump.

 

[Delmer]

Second that, way too milky, way too much water in the oil.

You're going to be changing the fluid several times, or taking flushing each circuit individually to get rid of all of the VISIBLE water.

There are other options for removing the water like vacuum "dehydration?" or heating the oil. Drain as much as possible like 707 said, dry the oil, filter it and return it. Run the machine and repeat until the oil stays clear, then change it.

 

[digdig]

That is way too milky. You need to flush your system if the rest of the oil in the tank looks like whats in the picture, probably have some corrosion inside your tank aswell. Position the machine so where you can retract most of the cylinders in. This usually for an excavator is stick out, bucket all the way out, boom down and blade up. Doing this will return as much of the oil back to tank. Pull the plug off the bottom but be sure you have a suitable container to handle 50L or so. You should not really be mixing viscosities, your pump may not like it and it could possibly hinder performance. Also you should change your filters and that o-ring in your picture looks no good either. once you have new fluid put in you can bleed the pump via the bleeder screw on top of the pump, not quite sure on the exact location but there definitely will be one on top of your pump.

Is this the bleed screw then?

There's 3 of these hoses coming out of the pump, I'd never even noticed the screw before.

So I do as you said with cylinders. Then drain off the old fluid, add new fluid then before starting the engine open the 3 screws, and then start engine and run the pump till the air has stopped bubbling out?

 

[Nige]

OK, to start with - viscosity. SAE10W is equivalent in viscosity to ISO AW32, not 46.

Next. That oil's got major quantities of water in it as other have pointed out, so you'd better be prepared to buy a sh1t-load of hydraulic oil & a few hydraulic oil filters (and a load of buckets, drums & whatever to drain the old oil into) because this will likely get very messy. Here's what I suggest over and above what has been suggested above by 707 & Delmer.

1. Don't just drain the tank, try and loosen everything that you can in the tank-pump-control valve circuit and drain the oil out of all the lines in that circuit. Then change the filter, fill the tank (a bit over-full if anything) and crank up the engine. Bleed the pump lines as suggested to get all the air out but DON'T touch any controls yet. That will keep the new oil from mixing to any significant extent with the old milky oil in the implement, swing, and travel circuits.

2. Next go to the implement circuit. Loosen the lines feeding oil to the lift cylinders for the raise function and try to drain the oil out of the bottom side of the cylinder. Then start the engine, gently move the lift lever to the "raise" position and watch the oil coming out of the loose hose connection(s) until you get clean oil coming out. At that point tighten them. Note that you have not moved the boom at this point.
3. Then loosen the hose(s) that carry the oil to the boom cylinder for the lower function and do the same as you did in point 2 above but this time moving the control lever to the "lower" position. When you get clean oil leave the hose connections loose - do not tighten them. At this point shut down the engine and top off the hydraulic tank. It will likely need it.
4. So now you have clean oil in the lines up to both ends of the boom cylinders but still the old oil in one end of the cylinder. Gently put the control in "raise" and watch the loose connection on the return line as the cylinders go up and all the old oil milky gets pushed out instead of being fed back to the tank. One the boom is fully up you can tighten the connections and lower it again. That circuit should be pretty much as clean as you can get it.
5. Repeat Steps 2, 3, & 4 with the Stick cylinder and the Bucket cylinder. Remember to keep checking and topping up the hydraulic tank as you go.
6. Now you've got the implement circuits reasonably clean move to the swing motor. Loosen one of the two lines on the motor for left/right swing, and also loosen the line that releases the swing brake. Hoick the boom up in the air and gently start to swing in one direction, stop when the swing brake line shows clean oil and tighten that line. Then keep swinging and once you get clean oil as far as the motor, stop and tighten the connection. Then loosen the other swing hose and repeat the operation swinging in the other direction.
7. You can do a similar thing for the travel motors as for the swing motor. The only thing you need do is use the bucket to lift one track off the ground so that you can rotate the travel motor. The only difference as far as the travel motors are concerned is that there is a case drain line on them that needs disconnecting to prevent the milky oil going back to the tank that way. Bleed the travel motor brake line first then bleed the forward and reverse hoses. Repeat the procedure for the other travel motor.

Even this procedure is not 100% guaranteed to get all the contaminated oil out of the system but I'd say done carefully it will probably get 95+% of it out.

BTW - Did I mention you're going to need a sh1tload of oil (and probably loads of patience as well if you want to make a good job of it)......??

 

[digdig]

OK, to start with - viscosity. SAE10W is equivalent in viscosity to ISO AW32, not 46.

Next. That oil's got major quantities of water in it as other have pointed out, so you'd better be prepared to buy a sh1t-load of hydraulic oil & a few hydraulic oil filters (and a load of buckets, drums & whatever to drain the old oil into) because this will likely get very messy. Here's what I suggest over and above what has been suggested above by 707 & Delmer.

1. Don't just drain the tank, try and loosen everything that you can in the tank-pump-control valve circuit and drain the oil out of all the lines in that circuit. Then change the filter, fill the tank (a bit over-full if anything) and crank up the engine. Bleed the pump lines as suggested to get all the air out but DON'T touch any controls yet. That will keep the new oil from mixing to any significant extent with the old milky oil in the implement, swing, and travel circuits.

2. Next go to the implement circuit. Loosen the lines feeding oil to the lift cylinders for the raise function and try to drain the oil out of the bottom side of the cylinder. Then start the engine, gently move the lift lever to the "raise" position and watch the oil coming out of the loose hose connection(s) until you get clean oil coming out. At that point tighten them. Note that you have not moved the boom at this point.
3. Then loosen the hose(s) that carry the oil to the boom cylinder for the lower function and do the same as you did in point 2 above but this time moving the control lever to the "lower" position. When you get clean oil leave the hose connections loose - do not tighten them. At this point shut down the engine and top off the hydraulic tank. It will likely need it.
4. So now you have clean oil in the lines up to both ends of the boom cylinders but still the old oil in one end of the cylinder. Gently put the control in "raise" and watch the loose connection on the return line as the cylinders go up and all the old oil milky gets pushed out instead of being fed back to the tank. One the boom is fully up you can tighten the connections and lower it again. That circuit should be pretty much as clean as you can get it.
5. Repeat Steps 2, 3, & 4 with the Stick cylinder and the Bucket cylinder. Remember to keep checking and topping up the hydraulic tank as you go.
6. Now you've got the implement circuits reasonably clean move to the swing motor. Loosen one of the two lines on the motor for left/right swing, and also loosen the line that releases the swing brake. Hoick the boom up in the air and gently start to swing in one direction, stop when the swing brake line shows clean oil and tighten that line. Then keep swinging and once you get clean oil as far as the motor, stop and tighten the connection. Then loosen the other swing hose and repeat the operation swinging in the other direction.
7. You can do a similar thing for the travel motors as for the swing motor. The only thing you need do is use the bucket to lift one track off the ground so that you can rotate the travel motor. The only difference as far as the travel motors are concerned is that there is a case drain line on them that needs disconnecting to prevent the milky oil going back to the tank that way. Bleed the travel motor brake line first then bleed the forward and reverse hoses. Repeat the procedure for the other travel motor.

Even this procedure is not 100% guaranteed to get all the contaminated oil out of the system but I'd say done carefully it will probably get 95+% of it out.

BTW - Did I mention you're going to need a sh1tload of oil (and probably loads of patience as well if you want to make a good job of it)......??

Thanks for that Nige, great post! That clears up a lot. You're right it's going to get messy, especially the swing lol.. The system holds 120L of oil according to the manual, so this will be pricey I'll probably get to changing the oil at the same time I reseal the cylinders. I'll update on how I get on..

 

[707]

Spot on nige, I would like to add on a few things. Make sure your implement is on the ground and not supported by the hydraulics before you crack any lines off and be mindfull that when you do try to crack a line and its way way to tight, it isnt't right. If it is it means its under pressure. When you do crack a line, crack it about half a turn and tap it with a hammer while your standing clear, this will break the hose loose causing it to dribble instead of shoot a few feet in the air. You may also dislodge the o-ring for that fitting so check before you tighten everything back up.

 

[aighead]

I hate to ask because it seems like a lot of work and money but is it safe to assume a similar process for clearing water from a backhoe hydraulic system? I also assume I could pay someone a bucket of money to do this for me?