Loosing power after 30–40 minutes use

[RJ Hamner 1,007]

Now that we are finding more uses for the 1990 520H with a KwikWay loader I am experiencing some power loss in the hydro after about a half hour to 45 minutes??????

Ideas?

[lynnmor 7,303]

What oil are you using in the hydro?

[953 nut 55,155]

May be worth considering an in-line oil cooler added to the filter line. Wouldn't cost too much and would likely do the trick.

[RJ Hamner 1,007]

28 minutes ago, lynnmor said:

What oil are you using in the hydro?

That might be a good question. The PO said he had just changed the filter. I assumed (I know) that everything was OK and didn’t give it a lot of thought. So, I am guessing that the first step will be drain and replace?  And since you can’t drain All of the oil ??????  What oil is supposed to be used?  
Would the hydro oil have a distinct smell if burned or contaminated similar to the smell from old type A?

Edited November 10, 2022 by RJ Hamner
Another what if

[RJ Hamner 1,007]

Looking at the flow chart in the Eaton 11 manual I’ve checked the level after every use and it’s been “in the green”. The fan and cooling fins were scrubbed and power washed right after I bought it. 
I don’t think I have overloaded it. Normally operate at 3000-3200 and use it mostly for mulch

[lynnmor 7,303]

Always change all fluids when buying a used machine, there is no way of knowing what is in there.  Your Owners Manual will show the correct information. I use a NAPA 1410 filter and Castrol semi-synthetic high mileage 10W-30 motor oil.  Blasting the transmission with a pressure washer is a good way to get water inside.

[squonk 41,050]

I would try 10W-40 synthetic. My C-160 with a Sunstrand can take both. It got weak when hot with 10-30 in it so I switched to 10-40 and it made all the difference.

[Snoopy11 5,714]

7 hours ago, squonk said:

I would try 10W-40 synthetic. My C-160 with a Sunstrand can take both. It got weak when hot with 10-30 in it so I switched to 10-40 and it made all the difference.

Is there any way that you could go into detail as to why this is the case, Mike? I've never heard that before, but as someone with several hydros, I think this would be great to understand!

 

Don

[squonk 41,050]

Hydros work with very close tolerances. As they wear those tolerances open up. As they open up pressures drop and so does the power. As hydros get warmer those tolerances open up more. Thicker oil fills in the tolerance gap some. The same way 40 wt. oil will keep the oil light from flickering at idle on a 76 Caprice wagon with over 300,000 miles on it. 

[pfrederi 17,697]

I think gear oil and or sawdust helped back then also

[lynnmor 7,303]

1 hour ago, squonk said:

Hydros work with very close tolerances. As they wear those tolerances open up. As they open up pressures drop and so does the power. As hydros get warmer those tolerances open up more. Thicker oil fills in the tolerance gap some. The same way 40 wt. oil will keep the oil light from flickering at idle on a 76 Caprice wagon with over 300,000 miles on it. 

You really need to replace "tolerance" with clearance, being an old tool & die maker it drives me nuts.

[Red-Bovine 309]

10w30 motor oil in the transmission. Also check to see if the fan blades are still on the pulley and clear out any grass and debris around the transmission. The transmission will get really hot if the fan is missing blades and junk is packed around it.

[RJ Hamner 1,007]

1 hour ago, pfrederi said:

I think gear oil and or sawdust helped back then also

Kinda like oatmeal in the radiator