new holland 33d blows hydraulic filter when clutch is released

[ncaldarone]

my new holland model 33d tractor blows the hydraulic filter when the clutch pedal is released. i am using a wix replacement filter. the top seal blows out and you can physically see the filter expand. way too much pressure

[jinman]

I would not use anything but the New Holland SBA340501030 part for that HST filter. When you release the clutch, the HST starts to pump fluid to the filter and cooler. In cold weather, the pressures are very high before the oil warms up. New Holland designed a rugged filter to take care of this problem, but with the Wix filter, you are NOT getting that protection. The NH filter is around $33 to $35, but worth it for the lesser hassle. When you install the NH filter, you want to make sure it is very tight. Unlike a filter for an engine, the HST filter needs to be tightened more than 3/4 turn after the gasket makes contact. I'd suggest turning it as far as you can by hand without using a tool.

[KPark]

I thought hydraulics were the same type of system as oil in a vehicle - Filter is on low pressure side because the pump (where pressure is produced) is downstream from it. That is why you only have to tighten the filters hand tight to keep a seal. If pressure is being introduced to the filter, I would suspect blowback from the pump, or something similar.

[jinman]

I thought hydraulics were the same type of system as oil in a vehicle - Filter is on low pressure side because the pump (where pressure is produced) is downstream from it. That is why you only have to tighten the filters hand tight to keep a seal. If pressure is being introduced to the filter, I would suspect blowback from the pump, or something similar.

Hydraulics in a tractor are nothing like the oil system in your vehicle. The oil in a vehicle's engine is there for lubrication only. It does no work whatsoever. Oil pressure is set so that it provides enough flow to cool engine parts and go through all the small openings and flow to all the parts that need lubrication and cooling while removing and suspending deposits. Comparing an engine's oil system to a hydraulic system is like comparing the cooling fan on the back of your computer to an air compressor. They both move air, but are completely different systems and do different work.

The main implement hydraulic system is also somewhat different from the HST transmission. It draws oil from a sump and puts it out under high pressure when required in order to do work. The suction side of the pump is essentially a vacuum, and the pressure side of the pump varies. On an open center system with nothing doing work, the pressure side of the system is low with maximum flow. When you close the system to do work like lifting the 3PH or FEL work, the pressure goes up and the flow slows a bit so that the system comes up to full rated pressure. However, when the work is done and the joystick centered or the 3PH reaches the specified point, the open center system goes back to low pressure.

An even different system is the HST transmission. It draws fluid from a reservoir the same as the main pump. Most of the time, the fluid is drawn through the same suction filter as the main implement pump uses and there is a "T" in the line to supply both the HST and main pumps. What draws fluid to the HST transmission is a charge pump. This is a low pressure pump that runs constantly at engine speed to provide the HST pump with fluid. By using a charge pump, when you step on the forward or reverse pedal and change the HST pump's swashplate angle, the HST can immediately respond because it has positive pressure on its inlet. In a way, it's like air being provided at positive pressure to an engine by a turbo-charger, but there is no lag in time with a HST because the charge pump runs all the time. On the New Holland compacts and many others, the charge pump draws fluid from the sump, but to make sure the fluid is clean enough for the HST, it sends the fluid on its outlet through a special HST filter and also a cooler. The pressure on the outlet of the charge pump can vary from 100 psi to 250 psi under normal operation depending on fluid temperature and the demand of the HST transmission. This pressure is felt by the HST transmission filter and is what can exceed the pressure rating of a less rugged filter so the filter expands and blows its gasket. This filter must be tightened more than other filters to ensure a tight fit of the gasket to the sealing surface.

So the flow for the HST system on the New Hollands is:

1. Fluid from the reservoir is drawn through the main hydraulic filter to the charge pump inlet.
2. Fluid leaves the charge pump under pressure and goes to the HST filter and cooler.
3. Fluid from the filter is presented to the variable displacement HST pump.
4. Depending on the angle of the HST pump swashplate, the fluid will be pumped to the HST motor under extreme high pressure (4k to 5k lb under load). Excess fluid at the pump is returned to the reservoir.
5. Fluid at the outlet of the HST motor is returned to the reservoir.

I hope this explains why the HST filter on a New Holland TC33D needs to be a New Holland made filter. In summer, you may get away with a lesser filter, but in very cold temperatures, you need that rugged filter case and gasket seal.

[V1Rotate]

Hydraulics in a tractor are nothing like the oil system in your vehicle. The oil in a vehicle's engine is there for lubrication only. It does no work whatsoever. Oil pressure is set so that it provides enough flow to cool engine parts and go through all the small openings and flow to all the parts that need lubrication and cooling while removing and suspending deposits. Comparing an engine's oil system to a hydraulic system is like comparing the cooling fan on the back of your computer to an air compressor. They both move air, but are completely different systems and do different work.

The main implement hydraulic system is also somewhat different from the HST transmission. It draws oil from a sump and puts it out under high pressure when required in order to do work. The suction side of the pump is essentially a vacuum, and the pressure side of the pump varies. On an open center system with nothing doing work, the pressure side of the system is low with maximum flow. When you close the system to do work like lifting the 3PH or FEL work, the pressure goes up and the flow slows a bit so that the system comes up to full rated pressure. However, when the work is done and the joystick centered or the 3PH reaches the specified point, the open center system goes back to low pressure.

An even different system is the HST transmission. It draws fluid from a reservoir the same as the main pump. Most of the time, the fluid is drawn through the same suction filter as the main implement pump uses and there is a "T" in the line to supply both the HST and main pumps. What draws fluid to the HST transmission is a charge pump. This is a low pressure pump that runs constantly at engine speed to provide the HST pump with fluid. By using a charge pump, when you step on the forward or reverse pedal and change the HST pump's swashplate angle, the HST can immediately respond because it has positive pressure on its inlet. In a way, it's like air being provided at positive pressure to an engine by a turbo-charger, but there is no lag in time with a HST because the charge pump runs all the time. On the New Holland compacts and many others, the charge pump draws fluid from the sump, but to make sure the fluid is clean enough for the HST, it sends the fluid on its outlet through a special HST filter and also a cooler. The pressure on the outlet of the charge pump can vary from 100 psi to 250 psi under normal operation depending on fluid temperature and the demand of the HST transmission. This pressure is felt by the HST transmission filter and is what can exceed the pressure rating of a less rugged filter so the filter expands and blows its gasket. This filter must be tightened more than other filters to ensure a tight fit of the gasket to the sealing surface.

So the flow for the HST system on the New Hollands is:

1. Fluid from the reservoir is drawn through the main hydraulic filter to the charge pump inlet.
2. Fluid leaves the charge pump under pressure and goes to the HST filter and cooler.
3. Fluid from the filter is presented to the variable displacement HST pump.
4. Depending on the angle of the HST pump swashplate, the fluid will be pumped to the HST motor under extreme high pressure (4k to 5k lb under load). Excess fluid at the pump is returned to the reservoir.
5. Fluid at the outlet of the HST motor is returned to the reservoir.

I hope this explains why the HST filter on a New Holland TC33D needs to be a New Holland made filter. In summer, you may get away with a lesser filter, but in very cold temperatures, you need that rugged filter case and gasket seal.

Great explanation, thanks for sharing.

[RickB]

Customer came in Monday and put a Wix hydro filter on the counter; asking why 4 of them in a row blew out the seal. I told him I didn't have to make excuses for aftermarket filters that somebody else sold, but the filter obviously isn't up to the task. He bought a NH SBA340501030 filter and 5 gallons of hydraulic oil. I didn't ask how much he saved buying the Wix filters.
After having frustrating problems of a similar nature with prior NH OEM hydro filters in the past, the current part number is doing just fine after three or so winters of use.

[tow653]

Will I have the same problem with a TC29,gear transmission? Put a Wix on late summer,no problem yet,should I expect one or is gear transmission different? Thanks,Tim

[RickB]

Will I have the same problem with a TC29,gear transmission? Put a Wix on late summer,no problem yet,should I expect one or is gear transmission different? Thanks,Tim

Gear transmission has only the hydraulic suction filter. The filter in question here is the hydrostatic charge pressure filter. Hydro tractors have this filter as well as the one your gear drive tractor has.

[tow653]

Thanks Rick! Tim