filter issue?

[mga]

let my brother-in-law use the splitter. they split like a million pieces of wood and he says the filter started to leak slightly. so, i bring it home and check it out. remove the filter, clean the seal, replace it. check the lines...all clear. remove the vent cap and run the engine. the oil flows very well.

so, i put a gage on the filter and run the engine again. it reads less than 10 lbs psi...ok..normal readings, filter not blocked. so i cycle the splitter a few times and i finally get it to leak. it leaks when the ram hits the end of the extend or retract cycle. at this brief moment, i notice the gage dropping to below zero..meaning there is negative pressure in the filter for a second or so.

during the actual cycle there are no leaks around the seal. it appears that a vacuum is created at the end of a stroke for that brief second or so and possibly expanding or retracting the filter somehow, but enough to briefly leak around the seal. so, i have a couple of questions:

1. how tight should i have that filter on there? like a car, i hand tightened it...or should i apply some good force on it?

2. what exactly is going on for that split second? the gage never reads over 10 PSI but it does drop below zero for a sec. should i put some directional valve or check valve on the return line?

other than that, it runs like a bear.

 

[Patrick62]

That is a good puzzle.

I have never seen one do this, but for what it is worth (2 cents):

Cylinder is moving, and then reaches the end of stroke. Oil flow briefly stops while the valve builds up pressure to kick it out. This is your negative pulse (oil in motion, creates vacuum.....). However! Now the valve has built it's required 500-600 PSI that kicks the valve into neutral. Oil flow now resumes, starting from a slight vacuum to hundreds of psi all at once. A surge. I am willing to bet that this is what is causing a leak. Can't be much of a leak. If there is a fair amount of hose between the filter and the tank that would add to the back pressure. The filter adds backpressure anyway. I would think that if the filter is screwed on firm enough that it would work. oil filters on vehicles run at up to 70 psi, so the O ring is capable.

-Pat

 

[mga]

you're right, pat, it's not a big leak, but after a while it builds up and drips down the side of the filter. more bother some than anything else. maybe i'm a bit anal about the leak, but it's there and it shouldn't be.

the hose from the valve to the filter is about 14" or less. using one hand on the valve and one on the filter, i managed to get an extra little turn on the filter when it reached that point. maybe the "surge" allowed it to turn slightly tighter.

i'll have to get some wood and run it thru and see what happens. if it still leaks, i'll just replace everything. a complete filter is about 15 bucks anyways.