Service & Maintenance Question
I have a H340. Please give me an answer of why the oil will...
Service & Maintenance Question posted October 5, 2014 by Lee Noga
220 Views, 12 Comments
Question:
I have a H340. Please give me an answer of why the oil will continue to leak out the outlet hole to the chain bar which is 3" above the base of the saw, when the saw is sitting on its base and not running?? This is nearly to the top of the oil reservoir and yet all of the oil will leak out of the outlet hole until all of the oil in the tank is nearly empty. The simple law of hydraulics says this cannot happen. The only other solution would be different pressures between the oil reservoir and the outside air. This has me stumped. Is there any solution???
Lee
Lee
Answer
the law of hydraulics says it will happen, that is exactly the science that supports the event. while the miniature pump does increase oil flowing into the bar to lubricate the chain, it is still gravity fed.
mr. noga, if you place a hose into any container of fluid, and suck on the hose until a flow starts, wouldn't you expect the flow to continue until the container was emptied? the worm gear in the pump is a spiral ladder. it will not prevent the fluid crawl as long as the flow has not been interrupted.
the best solution is to evacuate all fluids before putting the saw to bed. dump the fuel into an old prego jar and start the saw using light throttle until starvation kill. then empty as much oil as possible in a short period of time into any suitable container. (I use an old milk jug with 1/2 of the top cut away). I do this with all of my saws.
put them to bed clean and empty, and most performance issues disappear.
when I arrive to collect up my saws, I still arrive to find a puddle, but it is a very small puddle...
hopefully you use a compressor to perfectly clean the bar and clutch/oiler area. this is my M<O<. have good luck out there.
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the elevation that the fluid climbs thru is immaterial, when that flow has been started within the hose, it will continue that flow as long as the destination is at, or below its starting point...
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if you doubt the science of fluid dynamics, then I suggest you place any container of water into your bathtub. you can use a 5 gallon bucket if you like. the walls are very tall. then place a hose into the bucket and suck on the end of the hose until a flow starts.
then just sit back and watch as the bucket empties...
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It is another possibility depending the age and usage. It could be that oil pump assembly and seal are leaking. I had a Poulan 2550 last year in the shop that would leak all the oil out when it was left sitting a few days unused. It turned out that to be leaking between the oil piston pump and the oil pump cylinder due to normal wear. I would try replacing the oil pump piston,cylinder, and seal and see if this resolve the problem. These parts are fairly reasonable in price to replace. Note: there will always some oil leakage.
Part numbers: 503854801, 537154801, and 540057901. There is also a small pin (503240905) shown in the IPL that may be needed; just depends if you can recover the one you have or if you lose it.
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Lee,
I believe there are four possibilites, so here are my thoughts.
1. I would check for leaks and seals first as suggested by Eugene, many of the oil line hoses are shaped with a bulge or grommet built into the oil lines, and over time or If not properly installed initially they will leak. I would refer to the IPL drawings to see exactly how the oil line is routed, and if there is one or two oil lines. Usually on the newer chainsaws there is an oil line from the bottom of the tank to the suction side of the oil pump, then a second line from the discharge of the pump to the outlet near the bar hole in the engine casing. So you need to check those (4) locations for leaking oil (bottom of tank, suction side, discharge side, and outlet hole at bar). Its not real difficult to check but may require some dissassembly to get to the oil lines and pump. In addition a split or bad oil line can leak, if its the one on the bottom of the tank it will drain the entire tank. I have re-built and sealed oil lines and grommets using a very small amount of "Ultra black" silicone (oil resistant) and removed the oil lines and then when putting them back together just a small dab of sealant at each of the 4 locations seems to solve the problem, but an excess amount and you will plug the oil holes which are very small, so this is usually a last resort fix.
2. Lee, I agree with you about the physics or laws of hydraulics, it would be neat if we could make oil run up hill, we wouldn't need any pumps, however I think what Robert was referring to is "Syphoning effect" which will work with a tank of water and a hose as described by Robert, but I don't believe that is your problem.
3. There is also a Phenomenoa known as "Capillary effect", which is very real and will work on small diameter tubes (hence capillary) and high viscosity fluids, whcih does exist in bar oil another similar effect is "Wicking", and this will cause a liquid to flow or drip to a higher level then the level of the tank. I have seen this effect occur on oil caps, yes really an oil cap that leaks a very small amount thru capillary attraction or wicking, can drain a tank of oil, so check the seal around the oil cap or replace it. I had a chainsaw that I was sure was puddling oil from underneath the chainsaw, but it wasn't it all leaked out through the oil cap. I cleaned the oil gasket around the cap, and cleaned the flange on both the cap and tank, and the oil leak stopped also an easy fix.
4. Finally reason number 4, pressurization of the oil tank and a little history about chainsaws. Very early chainsaws used Pulse line pressure from the engine to pressurize the oil tank, and then a single oil line was used to feed oil from the tank to the bar, latter on they added oil pumps (~ late 70's & early 80's) and pumped the oil out of the top of the tank and the pumps were operated off the pulse line engine pressure to make the pump work (but the key is that they were pulling the oil out of the top of the tanks). Latter on maybe like (~ early 90's to present) they used geared pumps which were driven by the crankshaft but the suction oil lines were put in thru the bottom of the tanks (and Not thru the tops). Ok - so enough with the history, so why did I tell you all this info ? Because it is possible, and I actually had it happen to one of my chainsaw to pressurize the oil tank and drain all the oil from the tank. I stored one of my chainsaws in a storage shed, the chainsaw was in a case, and the shed during the summer months got to over 100 degrees, the temperature created pressure and emptied my chainsaw bar oil into the chainsaw case. There was no broken lines or hoses and there was no leaks, I took the engine apart to make sure. So it definitely was the pressure pushed the oil out of the tank.
Anyhow, Thats my four reasons, lots of food for thought, and hope I wasn't too wordy but it sounds like your a person that wants to figure out why this is happening, so start by looking at Eugenes' suggestion first, look for bad hoses, and leaks, and Oh don't forget about the possibility of the oil cap, maybe try that one first. Its an easy fix if it works.
Please let me know what you discover, and I hope this helps.
PS. I am Not a Husqvarna Representative or Authorized Repair, just an Experimental Chainsaw Person
Karla
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To Permaliink & others.
Your reply surely has merit however I am still not convinced regarding your explanation pertaining to this problem. Lets take a for instance of siphoning gasoline out of an auto. Yes if you suck on the tube you can get gasoline to flow. But the container you are siphoning into, must be lower than the auto fuel tank, It you raise the container above the fuel tank the gasoline will stop, or flow in the opposite direction will it not?? Thus gravity is still the main ingredient here I feel. Am I wrong?
I still do not feel confident of the true cause of this leaking problem. Perhaps wicking or capillary effect might have something to do with it but not sure. With the bar off, you can see the oil leak out almost full tilt which seems more than capillary action would be capable of also.
I also cannot see a pressure difference as a cause here also since opening the cap to be assured the pressure is the same will still give the same results. Oil leaking from the outlet hole.
Being one that does not like to walk away from something without a plausible answer, I would still like to get some other comments if possible. Has anyone really tried to get to the bottom of this problem? From a service station about all they say is that they all leak some. But why??
This is not a desirable feature, and I would think a chain saw mfg would have a simple solution.
Lee
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Lee,
Just one other thought but I'm sure you are probably aware, that the oil tank also has a vent, usually they are a "duckbill" type vent, which acts like a check valve, allowing air to go into the tank but since its one way, it will not allow air or liquid to come out of the vent.
I don't think that could be your problem, but its usually easy enough to replace, However I am not exactly sure where it would be located on the model 340, but again If you refer to the IPL drawings, you may be able to locate it, and try replacing it or testing it.
Also a Husqvarna Representive does review the posts, so Hopefully you will get an answer.
I am voting for some kind of capillary action that is occuring, (If there are no real leaks or problems but it continues to drip out of the outlet bar hole). Especially since you stated leaving the oil fill cap open, so it really can't be a venting problem. Anyhow the only re-design that I could think of is possibly building a bladder type tank that will expand and contract, allowing a little room inside the oil tank or going back to a pump that pulls oil out of the top of the tank, but not sure why that would be better either.
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if the test that I prescribed is proven to stop the leak/flow of oil, then refer to my previous postings and you will have your answer to why...???
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I do not fully understand you answer but will take the plate off again to view. From memory I noticed only one hole from the oil tank directly into the pump which is about an inch or slightly less lower than where the oil is sent to the bar. The pump only has a round shft with a flat spot. Spinning this flat spot is what forces the oil up through the seal and up to the bar. There is only a small hole from the oil reservoir and I would think that when the shaft round part is over this hole no oil could get any further. If the round part was not over the hole, then I could see some oil getting into the seal and up to the bar. But only gravity could push it up there. I am still out to lunch on this one, but will look still again. I have had the clutch off etc so many times inspecting that I will perhaps wear out the threads etc.. I noticed no air hole as you mention but there must be one somewhere. I have absolutely no leakage anywhere from the tank to the seal. The plate fits tightly on the seal thus no leakage there. It is all out of the exist hole which is 3" from the base. The top of the oil filler cap is also 3" thus if I use the gravity theory no oil should flow.
Lee
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step #1. dump oil into any container.
step #2. blow out entire oiler area and wipe it clean and dry.
step #3. wait 10 minutes and visually inspect the oiler area to be certain oil is not leaking.
step #4. refill oil tank, then watch carefully to see if any oil starts leaking.
if there is no oil leaking then you will know exactly what to do after every use of the saw. please just do this simple test.
goodnight...
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