X728 noisy hydralics when cold

[mikefamig]

I have been reading about why hydraulic pumps are noisy when the fluid is cold. I read about higher viscosity of cold fluid and cavitation often due to a clogged filter or other obstruction in the intake hoses causes the pump to draw air.

My tractor has ~450 hours on it and runs great. I have changed the hydro oil and filter once in the recent past. I used the correct Deere low viscosity hydr oil and only recently has the pump gotten really noisy when cold. The fluid is full and the noise goes away when the engine and fluids warm up.

I plan to change the fluid filter just for good measure and to see if it helps but I have a question for the group..... does the deere X728 have a hydraulic sump screen in addition to the screw-on fluid filter? My local dealer tells me that it does but I can't find it in my technical service manual. I was told that I would need to remove the left rear wheel to access and clean it.

Mike.

 

[ruffdog]

You should hear brand new tractors at the dealer when they are started COLD.....they make noise too.

 

[mikefamig]

New development - I just got off the phone with a second Deere dealer and they tell me that there is no sump screen on the X728, only the screw-off filter.

I failed to mention in my original post that I heard air rush into the hydraulic reservoir when I unscrewed the dipstick cap from the tank. The first dealer told me that there was no vent on the system and that the air rushing into the tank was normal.

I found it hard to believe that the system was designed with no vent which prompted me to call a second dealer. The second dealer tells me that there is a vent on the top of the rear axle and that it is probably clogged.

Mike.

 

[mikefamig]

You should hear brand new tractors at the dealer when they are started COLD.....they make noise too.

I really should do that but I have owned this one for seven seasons and it is louder than it has been in the past.

 

[Deere Dude]

I heard of people changing filter and the new one had plastic over the opening.

 

[mikefamig]

I heard of people changing filter and the new one had plastic over the opening.

WOW Not Good!

I changed the filter a year or two ago and it's been normal/quiet up till now.

 

[mikefamig]

I went out and started the tractor cold for two days in a row now and the terrible hydraulic noise is gone. I changed nothing, it just went away. The only thing that is different is that I didn't warm the machine up to full running temp. If the noise returns when I work the machine I'll open the dipstick and see if I hear the air rushing into the reservoir again. Maybe I'll get lucky and it'ss never happen again.

Mike.

 

[beenthere]

.................. different is that I didn't warm the machine up to full running temp. ...........

Mike.

Not at all sure what you mean by this.. What is "full running temp " ??

 

[Rustyiron]

Noise or no noise, I like to fully warm up a "hydro" machine. In my thinking at freezing or below, a simple "O" ring can be pretty hard and not so flexible especially in an environment that see's psi's in the thousands, and seeing that "O" rings are basically a main component throughout your pumps, valves and motors in a hydrostatic tractor, that a $1.10 o ring that's $500 deep in labor well inside a tractor is worth considering it's happiness.:thumbsup: On my tractor (hyd. clutch) I'll take it out of gear and put it in forward or reverse moving the oil through everything with the tractor in park. My SS and excavators just give them 15 minutes or longer depending on the temps idling time. It may be a waste, but it at least gives me a warm & fuzzy feeling that I'm doing all I can outside of maintenance to keep it trouble free.

 

[mikefamig]

Not at all sure what you mean by this.. What is "full running temp " ??

Running temp is the temperature that the machine runs at under normal load conditions. My X728 has a pretty good cooling system and runs about mid scale on the temperature gauge in both summer mowing and winter snow removal. I have never put a thermometer on it.

Mike.

 

[mikefamig]

You make a good point. I have always let all of my tools warm up a little before putting them under a load but not as long as 15 minutes.

Mike.

 

[mikefamig]

Another question on the subject, has anyone changed out the Deere Hy-gard low viscosity fluid for something even lower viscosity? And what is the viscosity of Hy-gard fluid?

Mike.

EDIT

I did a search and learned that Hy-Gard low viscosity fluid is multi viscosity and rated ISO 32. ISO ratings are explained a little in the following link and from that it appears to me that it's about 10 weight.

Viscosity Charts - Bob is the Oil Guy