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.

 

[ponytug]

If you have already tried a second filter, I would try tightening the hose fittings on the filter, and on the pump. I would be very surprised if they were loose, but strange things do happen. Be careful not to torque the hoses when you try to tighten the ends; you need a wrench on the hose, and a second wrench to do the tightening. (You probably know that, but just in case...)

I would then tighten the second filter another 1/4-1/2 turn. If that doesn't work, I would also have another close look at the sealing area on the filter housing for the gasket, and blow it out with brake cleaner, then air to clean it out.

All the best,

Peter

 

[m5040]

They don't call them hairline cracks for no reason, very hard to notice. Dont want to hijack the tread, but what does everyone think about if he actually started the engine by using the Deutz shutdown lever to keep it from starting (not unplugging the connection) and as the engine was cranking, slowly move the shutdown lever to the run position. This would attain a less then idle speed. Then he wouldn't damage the starter. It would take a helper to watch for air. Just a thought, something I would do to preserve the starter, but I actually take out the spark plugs on my 180 PT just to make it turn faster and easier.

 

[joshlee]

So John, your saying about running the engine in order to purge the air out of the hydraulic pump? Just today and yesterday I probably put more wear on the starter than the four years I had it.

They don't call them hairline cracks for no reason, very hard to notice. Dont want to hijack the tread, but what does everyone think about if he actually started the engine by using the Deutz shutdown lever to keep it from starting (not unplugging the connection) and as the engine was cranking, slowly move the shutdown lever to the run position. This would attain a less then idle speed. Then he wouldn't damage the starter. It would take a helper to watch for air. Just a thought, something I would do to preserve the starter, but I actually take out the spark plugs on my 180 PT just to make it turn faster and easier.

 

[joshlee]

I went around to most of the fittings, hoses, couplings, that are connected to the filter housing lines, and the oil filter seal with shaving creme while I cranked the engine, as means of trying to find the vacuum leak. The shaving creme was undisturbed at all the places I checked so far. I'll try to finish up the rest of the places tomorrow. The oil filter gasket doesn't have a vacuum.

This is an important question because it will greatly narrow down the possibilities of where the leak is, so if anyone has an answer, please let me know. Is this vacuum leak coming from only the suction lines that are attached to the hydraulic filter housing? Or could the vacuum be coming from almost any fitting/hose/coupler etc. that is attached to the hydraulic pump?

Thanks again.
Josh

If you have already tried a second filter, I would try tightening the hose fittings on the filter, and on the pump. I would be very surprised if they were loose, but strange things do happen. Be careful not to torque the hoses when you try to tighten the ends; you need a wrench on the hose, and a second wrench to do the tightening. (You probably know that, but just in case...)

I would then tighten the second filter another 1/4-1/2 turn. If that doesn't work, I would also have another close look at the sealing area on the filter housing for the gasket, and blow it out with brake cleaner, then air to clean it out.

All the best,

Peter

 

[ponytug]

I went around to most of the fittings, hoses, couplings, that are connected to the filter housing lines, and the oil filter seal with shaving creme while I cranked the engine, as means of trying to find the vacuum leak. The shaving creme was undisturbed at all the places I checked so far. I'll try to finish up the rest of the places tomorrow. The oil filter gasket doesn't have a vacuum.

This is an important question because it will greatly narrow down the possibilities of where the leak is, so if anyone has an answer, please let me know. Is this vacuum leak coming from only the suction lines that are attached to the hydraulic filter housing? Or could the vacuum be coming from almost any fitting/hose/coupler etc. that is attached to the hydraulic pump?

Thanks again.
Josh

Hi, yes, you are only looking for leaks on the suction side of the filter. Anywhere else will leak, or spray, oil.

Shaving cream, while creative, probably isn't thing to use to find an air leak as it will get sucked into your oil.

Random idea, and definitely a YMMV idea: I have had one JIC fitting crack, about forty hours into use. That would cause an air leak if it were on the suction line.

All the best,

Peter

P.S. @m5040: I believe the logic on not running the engine to purge the oil is to limit heat build up in the un/under-lubricated charge pump. I don't know for sure.

 

[ponytug]

They don't call them hairline cracks for no reason, very hard to notice. Dont want to hijack the tread, but what does everyone think about if he actually started the engine by using the Deutz shutdown lever to keep it from starting (not unplugging the connection) and as the engine was cranking, slowly move the shutdown lever to the run position. This would attain a less then idle speed. Then he wouldn't damage the starter. It would take a helper to watch for air. Just a thought, something I would do to preserve the starter, but I actually take out the spark plugs on my 180 PT just to make it turn faster and easier.

I like the idea of removing the spark plugs. Brilliant! It is a great compression release.

And definitely +1 on hairline cracks. They are really hard to find.

All the best,

Peter

 

[m5040]

The vacuum leak problem can only occur on the hose assemblies that exit both sides of the hyd filter. One goes to the tank and one goes to the pump. The problem can occur anywhere with these items.
I worry about giving some advice that needs to be used with caution. This is that kind of advice, think it over and fully understand before you attempt it. If you remove the filler cap on the hyd reservoir and make a plug/adapter, it can be pressurized with somewhere around 2 psi, maybe up to 3 or 4, but you would go up very slowly and look for the hyd tank expanding. You are dealing with pounds per every square inch and it ads up. When you pressurize it, you will have to wait for hours but you may notice the leak(s). You will need an accurate gauge and look/listen to the filter can and the hyd tank for bulging. You don't want to burst it. You may just want to drain the tank and take off the suction hoses and filter housing, examine on bench under bright light maybe with magnifying glass or just replace with new parts. Loctite makes a special tread locker/sealer for use in hyd systems. If you go that route you might want to use it. Just some thoughts. Running the engine at a slow idle was just my idea to make 110% sure you indeed have a problem.

 

[SpringHollow]

I almost always have a hard time getting the filter to not leak on two different PT1850's. There are two different types of seals available for my filter, one "L" shaped in cross section and one just rectangular. Sometimes one works better than the other. But I almost always end up crushing the filter some trying to get it tight enough to not leak. I just purchased a large metal band clamp to see if it works better than a normal strap wrench.

Ken

 

[joshlee]

I FOUND THE PROBLEM!! It was a tiny crack in the hydraulic filter housing. I unbolted it and was inspecting it under 4X magnification and seen two places where there were very tiny cracks. Neither one of them looked like a "smoking gun" to me, but I put a small dab of shaving creme on the one ( Ponytug, I tried using oil but it was too hard to see ) and turned the engine over to watch the bubbles come out the hose. To my amazement the bubbles stopped! I went over and looked at the shaving creme and a little bit of it got sucked in! I cleaned it the best I could and put a dab of high strength Locktite on it and turned the engine over again; no bubbles. So, I closed everything up on the pump and am going to order a new hydraulic filter housing tomorrow.

All of you guys (Ken, John, Ponytug, Mossroad, Oosik, Cqaigy), I want to say thanks for your help. Some of you have helped me out multiple times with issues, I appreciate it.:thumbsup:

Josh

 

[ponytug]

Congratulations! That's great that you found the issue. (Sorry about the cracked filter housing.)

All the best,

Peter