Hydraulic Filter Change Problem

[joshlee]

Hey everyone. I was wondering if some of you could help me with this issue I'm having with changing the hydraulic filter? I'm not able to purge all of the air out of the pump. I took the filter back off and cleaned around the place where that rubber seal fits up into that filter housing. I even used grease on the rubber seal the second time, thinking that might fix the problem; nope. I tightened the filter more ( now I'll probably have a hard time getting it off.) There are no leaks anywhere. Would any of you have any idea how the air is getting in?

Josh

 

[oosik]

I wonder why there is such a problem with your Power Trac. Is your hydraulic fluid level up to full. Somebody who owns one will probably have the answer. Hang in ........

 

[m5040]

Look real close at the aluminum filter mounting head and make sure it didn't crack when your were torquing off/on the filter. It may have cracked at the tapered pipe thread for the fittings or around the mounting bolts. How old is the machine, how many hours? Are the suction hoses going to/from the filter housing brittle or have cracks?

You are dealing with the suction side of the hyd system, so any oil leaks tend to be very minor (because they only come from gravity). The real problem is air leaking into the system (as you see) when the pump is drawing or attempting to draw oil up.

Do you have another filter to try, maybe that one has a bad crimp around the shell?

How long have you tried to bleed the filter? 5 seconds or 1 min+?

You probably don't need me to say it, but you have a defect and you need to look extremely close and feel with your fingers for irregularities to find it.

 

[MossRoad]

Since you're fairly certain your filter is on tight and correctly, next, make sure your bleeder hose is on the fitting snuggly and the other end is down far enough into the reservoir. Crank the starter for no more than 10 seconds at a time, then let it sit for several minutes before the next cranking so you don't overheat the starter. Repeat. Eventually the air will work out. That's the way I've done it. Sometimes it only takes a few cranking sessions and sometimes it took a few more.

How many cranking sessions have you done at a time?

 

[joshlee]

Hey John, thanks for the advise. I'm going to go out right now and check for cracks in that filter housing and if thats not the case I'll try a new filter. The machine is only 4 years old, so all of the fittings look good. When cranking the engine to get the air out of the pump, I cranked it for minutes. The battery eventually went dead, so I've had it on the charger while trying different things to fix the problem, then crank it more to no avail.

So, your saying that all of the hoses and port fittings that are not somehow connected with the suction hydraulic filter would not produce air in the system? If that's so, it would really narrow down the possibilities. From what I see, there is the port/hose on the bottom of the piston pump that goes to the filter, then from the filter a hose goes to the base of the hydraulic tank. So, the problem would be in that area?

Months ago when I changed the hydraulic filter, instead of loosening the cap on the side of the pump to attach the hose for priming, I accidentally loosed the hose right above it, but the JIC fitting didn't loosen, the fitting that the JIC fits to loosened. That goes right into the port. I just tightened it back up and went about things the proper way, and I got all of the air out of the system. I'm wondering if my blunder might have caused an air leak at that port right about the cap? It's just thought.

Josh

Look real close at the aluminum filter mounting head and make sure it didn't crack when your were torquing off/on the filter. It may have cracked at the tapered pipe thread for the fittings or around the mounting bolts. How old is the machine, how many hours? Are the suction hoses going to/from the filter housing brittle or have cracks?

You are dealing with the suction side of the hyd system, so any oil leaks tend to be very minor (because they only come from gravity). The real problem is air leaking into the system (as you see) when the pump is drawing or attempting to draw oil up.



Do you have another filter to try, maybe that one has a bad crimp around the shell?

How long have you tried to bleed the filter? 5 seconds or 1 min+?

You probably don't need me to say it, but you have a defect and you need to look extremely close and feel with your fingers for irregularities to find it.

 

[joshlee]

Hey Mossroad, thanks for trying to help me out with this problem. Yeah, I tried that stuff and nothing seems to work. Like I said to John, I cranked it way longer than needed, thinking there might have been a stubborn air pocket of something. I'll keep that in mind about not overheating the starter. I'll get back to all of ya here later and let you know what I've found out.

A little off the subject, but I've always been curious as to why Power Trac recommends a Hydo Filter change so often as opposed to other conventional tractor manufacturers. If someone uses these PT tractors commercially, they are probably having to change this filter every week.

Since you're fairly certain your filter is on tight and correctly, next, make sure your bleeder hose is on the fitting snuggly and the other end is down far enough into the reservoir. Crank the starter for no more than 10 seconds at a time, then let it sit for several minutes before the next cranking so you don't overheat the starter. Repeat. Eventually the air will work out. That's the way I've done it. Sometimes it only takes a few cranking sessions and sometimes it took a few more.

How many cranking sessions have you done at a time?

 

[joshlee]

I just got done doing those inspections. There doesn't appear to be any cracks in the filter casing, the filter that was used looked perfectly fine, although I replaced it to make sure. There is no change with that new filter on. ???? I'm not sure what the deal is?

 

[ponytug]

Sorry to hear about your challenges.

Are you getting big bubbles of air, or small foamy bubbles? The former is something open, the latter is a small crack/hair/piece of dirt somewhere.

Power Trac recommends frequent filter changes because these filters are used on the suction side, where there are two issues; 1) catastrophic filter collapse due to a clogged filter, and 2) cavitation causing filter erosion, allowing debris downstream to the variable volume drive pump. Having cold hydraulic oil makes both issues worse, as does a filter with trapped dirt.

Terry once said to me that working on the hydraulics is like open heart surgery; you want everything spotless and sterile. The comment has stuck with me, and I try to follow the advice.

• You won't see oil leaking from a filter that is too loose. At best, there may be a film of oil on the filter. I speak from experience. Those air bubbles shouldn't be ignored, as they will cause damage to your drive pump.
  
• It is possible that you have a defective filter, or seal. However, I would start by removing this filter, examining the filter, rubber gasket, and the housing groove for any imperfections or debris. I truly mean any. A hair, or a scratch on the metal surface, is more than enough. If your eyesight is like mine, I would toss the filter and the gasket and start over. I would also double check that the filter and gasket are the right sizes. I would then clean all the surfaces with brake cleaner, put fresh oil on the rubber gasket, and reassemble everything. This filter is not like an engine oil filter; you need to really torque this filter on.Before I start working on these filters, I blow the whole filter area clean with compressed air and clean all surfaces with clean paper towels and solvent. I also wear nitrile gloves, as it really helps me see when my fingers aren't totally clean, and thus at risk of contaminating the filter or gasket.
  
• I prefill this filter with oil. (Normally I don't do this, but pumping air through the variable volume pump isn't ideal either.) FWIW: It takes me one to two minutes total of cranking time to purge a filter that was installed tightly, and was mostly full of oil to begin with. You don't want to crank for extended periods of time because it will burn up your starter. Engine starters are basically a short circuit across a battery, and get hot pretty quickly. They are designed for a few seconds of use, not extended cranking. If you ever replace your starter, trying to get a more powerful replacement. It really helped me with cold starts.

When removing my filter, it takes me a two foot 1/2" drive breaker bar on a 2 1/2" nylon strap to remove my filters. Anything less leaks air, at least in my experience.

I hope that this helps.

All the best,

Peter

 

[joshlee]

Yeah, the oil level was the first thing I checked. That would have been an easy fix.

I wonder why there is such a problem with your Power Trac. Is your hydraulic fluid level up to full. Somebody who owns one will probably have the answer. Hang in ........

 

[cqaigy2]

On my 422, i think it was the second or third filter change. I wasn't able to purge, i was sure the filter was on tight enough, but went back at it and tightened it much more then i thought would be needed. Probably has to do with be on the suctions side.