Does it matter if FEL is attached when changing hydraulic/HST fluid and filters?

[Texasmark]

I don’t understand - attached or disconnected, there will always be oil in the loader cylinders that don’t get changed.

Yepper, bidirectional cylinders have fluid on both sides of the ram. Only way to get it all out is to dismantle the hydraulics piece by piece. Besides, considering the volume of the FEL system vs sump, not that big of a deal.

Where the concern comes in is when you have hydraulically driven implements that you use on different tractors. That's where the problem lies...old implements having been driven by old tractors not requiring today's lubes, or full of water from sitting out for years in the weather.......

 

[Tennsawdust]

Yepper, bidirectional cylinders have fluid on both sides of the ram. Only way to get it all out is to dismantle the hydraulics piece by piece. Besides, considering the volume of the FEL system vs sump, not that big of a deal.

Where the concern comes in is when you have hydraulically driven implements that you use on different tractors. That's where the problem lies...old implements having been driven by old tractors not requiring today's lubes, or full of water from sitting out for years in the weather.......

Exactly. With double acting cylinders there is no change in volume held regardless of position. Some older tractors used single acting cylinders on the loaders and there they recommended checking the fluid with all cylinders extended (loader up, lift up) so that you filled high enough to accommodate the full system volume required to operate everything.

 

[ericm979]

Unless it's a cylinder with the rod coming out at both ends (like are used for steering), the rod takes up some oil volume when the cylinder is compressed. Putting the loader down and curling the bucket would put the rods in the cylinders and take up that volume so there's a little more oil being changed. But it's a small difference that's not worth bothering about.

 

[RalphVa]

You're not draining fluid from the lines, only from the HST chamber. The HST fluid doesn't wear out or get contaminated (if filter is working) in the lines either, to need any changing.

Ralph