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Discussion Starter · #1 ·
Tomorrow, I will have had my 4520 for one year. I bought it with 1714 hours on it and the PTO clutches were shot. I had one of the local JD dealers install new PTO clutches. They put Low Viscosity Hy-Gard back in when they filled the transmission. It all worked fine until about May 5th when the temps started climbing.

While using the bush hog, the HST drive system would start slowing down to the point that the tractor would barley drive out of the ditches and would not load onto my trailer unless I got a running start in “A” range. I had about 55 hours on the tractor since the clutches had been replaced.

I tried using one more time and it did the same. I decided to drain the fluid and change the filter. I cleaned the suction screen which was full of old pto clutch debris. I removed the inline filter and blew it out. The mechanic who replaced the pto clutch said I would probably need to change fluid and filters a couple of times to flush all the clutch debris out. He said about every 50 hours. I put in low vis just like the mechanic put in the transmission and just like was stamped on the dip stick.

Fast forward for the next 50 hours. The tractor would not pull well after working for about an hour. I would stop and start again the next day. The tractor would seem to work well when starting a new day with cold fluid. I thought maybe my oil cooler was clogged up so I cleaned it very well using the new radiator genie wands I had ordered. It didn’t seem very dirty.

Cleaning didn’t help as it would still heat up and get very sluggish. I started digging through old threads on GTT and discovered Uncle Wayne and eePete had the same issues with their 4520 and 4720 machines. I had conversations online with both of them and they both switched to regular Hy-Gard or a mixture of regular and low vis.

I drained my transmission Sunday was a week ago, cleaned the suction screen which wasn’t dirty and blew out the inline screen. (I had replaced my inline screen as the old one was crushed. See another one of my threads.) I let the tranny drain for a week and got an extra quart and a half out of the system. I put the FEL back on before draining so I could drain it as well. I refilled with Regular Hy Gard.

Today I cut the 3.5 acres that I have been cutting and and was getting sluggish on. I had zero, zip, nada single problem for the 2 hours of cutting and for the 3rd hour in one of the fields. I cut the ditches and drove straight up on my trailer when I loaded up.

I noticed when I drained the low vis that it was almost as thin as water. I had worked the tractor for about 20 minutes before I drained it. When I filled the tranny with Regular Hy-Gard, I noticed that it smelled like gear oil where as the low vis did not have any noticeable odor.

I believe that if you live in the south, low vis is not for you. It is only good for ambient temps of about 80*. The regular viscosity is good to about 125* F. Secondly if you have a number of hours on your machine, there is some wear and tear there so the low vis may be blowing by your system. In my case I would say both apply. My 4520 seems to have starting working fine now with the regular Hy-Gard.

Thanks eePete and Uncle Wayne for your help and GTT for your archived threads.
 

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Tomorrow, I will have had my 4520 for one year. I bought it with 1714 hours on it and the PTO clutches were shot. I had one of the local JD dealers install new PTO clutches. They put Low Viscosity Hy-Gard back in when they filled the transmission. It all worked fine until about May 5th when the temps started climbing.

While using the bush hog, the HST drive system would start slowing down to the point that the tractor would barley drive out of the ditches and would not load onto my trailer unless I got a running start in “A” range. I had about 55 hours on the tractor since the clutches had been replaced.

I tried using one more time and it did the same. I decided to drain the fluid and change the filter. I cleaned the suction screen which was full of old pto clutch debris. I removed the inline filter and blew it out. The mechanic who replaced the pto clutch said I would probably need to change fluid and filters a couple of times to flush all the clutch debris out. He said about every 50 hours. I put in low vis just like the mechanic put in the transmission and just like was stamped on the dip stick.

Fast forward for the next 50 hours. The tractor would not pull well after working for about an hour. I would stop and start again the next day. The tractor would seem to work well when starting a new day with cold fluid. I thought maybe my oil cooler was clogged up so I cleaned it very well using the new radiator genie wands I had ordered. It didn’t seem very dirty.

Cleaning didn’t help as it would still heat up and get very sluggish. I started digging through old threads on GTT and discovered Uncle Wayne and eePete had the same issues with their 4520 and 4720 machines. I had conversations online with both of them and they both switched to regular Hy-Gard or a mixture of regular and low vis.

I drained my transmission Sunday was a week ago, cleaned the suction screen which wasn’t dirty and blew out the inline screen. (I had replaced my inline screen as the old one was crushed. See another one of my threads.) I let the tranny drain for a week and got an extra quart and a half out of the system. I put the FEL back on before draining so I could drain it as well. I refilled with Regular Hy Gard.

Today I cut the 3.5 acres that I have been cutting and and was getting sluggish on. I had zero, zip, nada single problem for the 2 hours of cutting and for the 3rd hour in one of the fields. I cut the ditches and drove straight up on my trailer when I loaded up.

I noticed when I drained the low vis that it was almost as thin as water. I had worked the tractor for about 20 minutes before I drained it. When I filled the tranny with Regular Hy-Gard, I noticed that it smelled like gear oil where as the low vis did not have any noticeable odor.

I believe that if you live in the south, low vis is not for you. It is only good for ambient temps of about 80*. The regular viscosity is good to about 125* F. Secondly if you have a number of hours on your machine, there is some wear and tear there so the low vis may be blowing by your system. In my case I would say both apply. My 4520 seems to have starting working fine now with the regular Hy-Gard.

Thanks eePete and Uncle Wayne for your help and GTT for your archived threads.
That is what I have posted many times in the LGT threads, that you need the proper fluids for the temperature range that you live and work in. Even in the upper mid west you may have to change fluids twice a year on machinery that can see regular 90-110 degrees F in the Summer and -40 - 32 degrees in the Winter.
 

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This is the transmission oil chart from the 4520 Operator's Manual.

752951
 

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Discussion Starter · #4 ·
Here is another temperature range chart from JD for Regular HyGard and Low Vis HyGard. Notice the difference in the temperature ranges. This one says 80*F. Deere seems to be telling two different ranges for the low vis.

752953
 

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Here is another temperature range chart from JD for Regular HyGard and Low Vis HyGard. Notice the difference in the temperature ranges. This one says 80*F. Deere seems to be telling two different ranges for the low vis.

View attachment 752953
no matter which of the 2 charts you look at, regular HY-GARD is a better fit for your climate.
Glad you are finally getting your issues worked out.
The low vis was probably better for flushing things out at least!
 

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The Low Viscosity Hy Guard really only makes sense when its very cold, which I doubt rarely happens in the south. In extreme cold, even the Low Guard fluid flows slower and the hydro pedals and levers can be really stiff until the fluid warms up. But otherwise, in warmer temps, I agree with running the Regular Viscosity hydro oil.

The PTO clutch generates a lot of heat and on the machines which have the radiator also serving as the oil cooler with the lower portion of the radiator circulating hydro oil, I have seen the heat from the PTO clutches in the summer increase engine operating temps by driving up the hydro oil temp which is circulating through the radiator. Once the radiator gets hot from the hydro oil, it's harder to get the tractor to cool down as there is such a large volume of Hydro oil and the oil cooler and even the section of the radiator dedicated to cooling the hydro oil is smaller than the section dedicated to cooling the engine.

I am glad the regular viscosity hydro oil has restored the proper function of your machine. If you don't have an infrared temp gun, I would suggest you get one and check the temperature of certain segments of the hydro system to see what the temps are now in the warmer weather. Such things as the Hydro Oil Filter and the temperature of the oil cooler or the section of the radiator which circulates the hydro oil verses the engine coolant temperature. It would be interesting to know what the temps were before with the Low Viscosity oil and now with the regular viscosity oil. At least you can compare the actual case and filter temps in the colder weather to see just how hot the hydro case gets with your machine use.

Don't be surprised to find the hydro pedals and the SCV lever with more resistance when the temps do get cooler in the winter. They will soften up as the hydro oil warms up and unless you get very cold weather, I doubt the pressure needed for the pedals or SCV lever will be troublesome. You will likely hear some more "whine" out of the hydro pump in the cold temps as well, but that goes away as the hydro oil heats up.

I wouldn't be surprised you notice the engine operating temp also decreases some while using the Regular Hydro Oil. Glad the fluid change to Regular Viscosity Hydro oil resolved your operational problems.
 

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Good info to know, when I ordered my 2520 in 2006 I got the optional block and transmission heater, sure makes her sound better when starting in very cold temps. Have not noticed any problems with power when bush hogging when it is hot. Glad you were able to get it figured out without going into a money wasting spiral.
 

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Discussion Starter · #9 ·
3.2 engine hours bush hogging today. Still no problems with the regular Hy-Gard. It would even Bushog straight up the 2:1 slopes with no problems. I think my problem is finally solved.
 
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