Beware of the shop-vac trick when changing hydraulic filters...

[ning]

There is no fluid at the fill opening, unless one has over-filled. So can't suck any oil out.

Basically the shopvac is taking a long bong rip. Just like the stoner doesn't get the stanky water because the air is sucked through the water, the shopvac pulls the air from the filter area through the fluid reservoir.

(nb I'm not a stoner and have never used a bong, but I've seen them used back in college and in movies... this was too good of an illustrative analogy to pass up)

 

[Midniteoyl]

(nb I'm not a stoner and have never used a bong,

 

[Smokeydog]

I will not be using a vacuum. Essentially back flushing the filter to the reservoir. 200hr hst transmission filter change with minimal oil loss. 400hr hst and hydraulic filters change with new fluid requires draining.

 

[IndyJay]

Basically the shopvac is taking a long bong rip. Just like the stoner doesn't get the stanky water because the air is sucked through the water, the shopvac pulls the air from the filter area through the fluid reservoir.

(nb I'm not a stoner and have never used a bong, but I've seen them used back in college and in movies... this was too good of an illustrative analogy to pass up)

Is a "stoner" a type of grapple? What's a bong? Do American tractors have them too?

 

[TMGT]

I will not be using a vacuum. Essentially back flushing the filter to the reservoir. 200hr hst transmission filter change with minimal oil loss. 400hr hst and hydraulic filters change with new fluid requires draining.

You're not backflushing the filter to the reservoir, you're just neutralizing the effects of gravity, no fluid is being moved.

 

[Smokeydog]

You're not backflushing the filter to the reservoir, you're just neutralizing the effects of gravity, no fluid is being moved.

I’m all for creative ways to keep our machines functioning properly.

I would like to see evidence of what you say is true. I don’t think that’s what people are doing. My shop vac can easily pull 3’ water column with considerable volume. Nobody is measuring or controlling the vacuum applied. Could a technique be developed with proper equipment do that job effectively? Maybe? Still a risk.

On my old geared tractors I wouldn’t be as picky. HST take extra special care and feeding to be reliable.

 

[ning]

I will not be using a vacuum. Essentially back flushing the filter to the reservoir. 200hr hst transmission filter change with minimal oil loss. 400hr hst and hydraulic filters change with new fluid requires draining.

Kinda hard to backflow something that's removed.

Until the filter is removed, there's no air available to flow through the hydraulic fluid and the shopvac is just pulling a vacuum in the tank (not great for the shopvac and a good reason to have an assistant who can keep the hose only partially attached so the motor doesn't work so hard); there's definitely no flow of hydraulic fluid (you think a shopvac is going to make the hydraulic pump operate?) through the filter.

As soon as the seal is cracked on the filter and air can flow into the tank from the filter port, the vacuum can pull air from there, through the fluid, and up the filler tube and into the shopvac.

The theory is good, but my tractor's filter replacement interval is the same as the fluid replacement interval, so this is just an amusing intellectual exercise (mind you, amusing more for the discussion than the application).