I have a Husqvarna YTH2454 around a 2008 model. As far as I can determine, it has a Tuff Torq K46 hyro trans in it. It looses drive speed and power as it heats up. I have replaced a worn drive belt and a locked idler. Used a Husqvarna Kevlar belt. Trans is clean and fan in good shape. Engine runs great and does not change in speed. If I believe what the previous owner says, he changed the fluid a couple years ago. I see there is a complete rebuild kit available, but I'm hoping not to have to go thru all that. What can I do? Thanks in advanced.
Hydro looses power as it heats up
- Thread starter Freddie21
- Start date
bertsmobile1
Lawn Royalty
- Joined
- Nov 29, 2014
- Threads
- 65
- Messages
- 24,995
You can use a heavier oil
Std is 20w50 but as the unit is worn 30w60 won't do much in the way of damage
Perhaps even a 40w70
To find the heavier oils the best place to go is a motorcycle shop that does HD parts
HD owners seem to delight in using the most expensive stuff around & the local bike warehouse is the only place I have ever seen 40w60 fully synthetic but you need to take the thick wallet cause it ain't cheap .
If you go the rebuild kit make sire you degrease then pressure wash the tranny before you pull it apart .
They are made is sealed dust free factories so being blaise about cleanness will end in tears in a couple of seasons .
My std test for hydros is my tilting trailer which goes to about 35 deg to the ground
Engine off, brake off
Almost impossible to push down the slope = excellent
Pushes but stops when I stop pushing = perfect
Pushes hard but rolls a bit then stops = starting to wear
pushes easily & keeps on rolling slowly = couple of seasons left
pushes easily & keeps on rollingquickly = might last out the year
Rolls away all by itself = worn out
Races away & flies down the road = dangerous & not to be returned with out proper repair
IfI catch them at the pushes easy stage then a heavier oil seems to work for 3 to 5 seasons
Std is 20w50 but as the unit is worn 30w60 won't do much in the way of damage
Perhaps even a 40w70
To find the heavier oils the best place to go is a motorcycle shop that does HD parts
HD owners seem to delight in using the most expensive stuff around & the local bike warehouse is the only place I have ever seen 40w60 fully synthetic but you need to take the thick wallet cause it ain't cheap .
If you go the rebuild kit make sire you degrease then pressure wash the tranny before you pull it apart .
They are made is sealed dust free factories so being blaise about cleanness will end in tears in a couple of seasons .
My std test for hydros is my tilting trailer which goes to about 35 deg to the ground
Engine off, brake off
Almost impossible to push down the slope = excellent
Pushes but stops when I stop pushing = perfect
Pushes hard but rolls a bit then stops = starting to wear
pushes easily & keeps on rolling slowly = couple of seasons left
pushes easily & keeps on rollingquickly = might last out the year
Rolls away all by itself = worn out
Races away & flies down the road = dangerous & not to be returned with out proper repair
IfI catch them at the pushes easy stage then a heavier oil seems to work for 3 to 5 seasons
Last edited:
- Joined
- Feb 19, 2020
- Threads
- 93
- Messages
- 11,609
While you were replacing the drive belt did you replace the plastic v-idler pulley? If you didn't that might be the problem as I have seen them to cause belt slippage problems even with new belts.
bertsmobile1
Lawn Royalty
- Joined
- Nov 29, 2014
- Threads
- 65
- Messages
- 24,995
Just be careful where you aim it at .
bertsmobile1
Lawn Royalty
- Joined
- Nov 29, 2014
- Threads
- 65
- Messages
- 24,995
It is hard to explain in words but there are a lot of You Tube videos about how a hydro works
Basically there are 2 critical parts , one revolved and the other does not .
Oil under very high pressure has to pass from the moving int the stationary part in the pump then from the stationary to the moving in the motor
There is no seal between these parts so the system relies on the resistance to flowing out of these parts due to viscious friction in the oil being higher than the resistance to flow caused by the pistons.
For this to happen both of the parts ( Valve plate often called kidney plate ) and the piston cylinder are machined to a particular roughness
Over time these two parts erode , so become smoother over all thus providing less resistance to escaping plus the space where the oil flows erodes a channel, just like a river gouges out a canyon over time.
The up shot of this is the box sort of works when the oil is cold & thick and looses power when the oil gets hot & thinner.
That growling sound you hear is the oil under pressure escaping out the sides of the piston chest .
Down here we now have 2 machine shops that clean up both faces then pack them out to remake the original clearance between them
In the USA where one would have imagined a clever machine shop would be doing thousands of them a week apparently it is far cheaper to do a drop in replacement of a new pump/motor unit.
Bigger tractors like the Kubota F2400 I am currently working on these 2 faces have drop in replaceable wear plates .
Basically there are 2 critical parts , one revolved and the other does not .
Oil under very high pressure has to pass from the moving int the stationary part in the pump then from the stationary to the moving in the motor
There is no seal between these parts so the system relies on the resistance to flowing out of these parts due to viscious friction in the oil being higher than the resistance to flow caused by the pistons.
For this to happen both of the parts ( Valve plate often called kidney plate ) and the piston cylinder are machined to a particular roughness
Over time these two parts erode , so become smoother over all thus providing less resistance to escaping plus the space where the oil flows erodes a channel, just like a river gouges out a canyon over time.
The up shot of this is the box sort of works when the oil is cold & thick and looses power when the oil gets hot & thinner.
That growling sound you hear is the oil under pressure escaping out the sides of the piston chest .
Down here we now have 2 machine shops that clean up both faces then pack them out to remake the original clearance between them
In the USA where one would have imagined a clever machine shop would be doing thousands of them a week apparently it is far cheaper to do a drop in replacement of a new pump/motor unit.
Bigger tractors like the Kubota F2400 I am currently working on these 2 faces have drop in replaceable wear plates .
bertsmobile1
Lawn Royalty
- Joined
- Nov 29, 2014
- Threads
- 65
- Messages
- 24,995
And keeping the case clean so it can radiate heat does not hurt either
I have "fixed" bad trannies by doing nothing more than removing 4" of baked on mud & grass clippings .
I have "fixed" bad trannies by doing nothing more than removing 4" of baked on mud & grass clippings .