Poulan Micro XXV Oiler Woes

[Rich Purdum]

I have done all of the recommended steps and checks to get the oiler working on my old Poulan XXV. The last step was to install a NOS crankcase check valve. When I rev the saw up with the bar off I can see oil trying to come out of the tube but it does not really flow. I have used a WD40 spray tube and my air compressor (set on low) blowing into the opening in the crankcase leading to the oil reservoir to verify oil will flow and it does. On my saw there is a "feature" which does not show up on the exploded parts lists. As can be seen in the photo, ti appears to be a "bent pin" which can spin freely in it's opening and I can see oil "seeping" out. I am guessing it is some sort of pressure relief mechanism but am hoping someone can clarify it function. If it is letting pressure escape I'd like to seal it up but wanted to check here first. TIA for any tips.

Rich

 

[blsnelling]

Have you replaced the pump diaphragm?

 

[Rich Purdum]

Have you replaced the pump diaphragm?

There is not pump diaphragm on these saws...the oiler is driven by pressure from the crankcase and controlled by two check valves, one on the crankcase and one in the oil chamber. I have confirmed both of these are "working" in that they only pass air in the correct direction.

 

[Toyboy]

That so called "bent pin" has a function and is part of the saw. Right now I can't remember what it does, but leave it alone.
If both check valves are holding the only other thing I can think of is your your losing pressure someplace. Those saws have a pressurized oil system and if you don't hold the pressure it won't work. You only have the oil tank gasket, engine check valve, oil pump and the lines that connect it.
Not a lot of places to deal with.

 

[Rich Purdum]

Toyboy, thanks for the advice. While waiting for suggestions on this thread I zoomed in on the Youtube video of the oiler repair and saw the pin and the oiler working so I totally agree...leave it alone. When I checked the saw I noticed a small pool of oil which seemed to be coming from the filler cap. I've replaced the o-ring but can't test things as the fuel tank repair I did gave way so I'm heading down to Tap Plastics to see what they can suggest for a fix. It's just a hairline crack (caused by me) and a pin hole leak (the problem I was trying to fix). I'm hoping they have a solvent/adhesive that will melt the plastic to seal the leaks. If all goes well I'll fire up the saw tomorrow morning and report results.

 

[Toyboy]

If/when you do get the oilier working, be sure to crack the oil tank cap to release the pressure when your finished cutting. Otherwise it'll keep pushing oil.

 

[Ozhoo]

...as the fuel tank repair I did gave way so I'm heading down to Tap Plastics to see what they can suggest for a fix. It's just a hairline crack (caused by me) and a pin hole leak (the problem I was trying to fix). I'm hoping they have a solvent/adhesive that will melt the plastic to seal the leaks. If all goes well I'll fire up the saw tomorrow morning and report results.

If you need another tank, you're more than welcome to this one. Just pm me your address and I'll get it out to you.

 

[Rich Purdum]

According to the manager at Tap Plastics, the tank is made from Polyethylene which is pretty much impervious to everything which helps explain why all my other repairs failed. Tap has a product called Poly-Weld which looks fairly simple to apply based on the video at their web site. It does not involve melting the polyethylene, just heating it, so I'm less concerned about totally ruining the tank. Funny, years ago I worked for a company called Raychem which made tons of high tech plastic produces. I'm sure one of the chemists in R&D could explain how this process works at the molecular level. I just hope it works. It would be nice to have a fool proof way of repairing and joining plastic.

 

[Rich Purdum]

Well, I'll have to say the Poly-Weld did work as advertised. Only problem was when I heated the tank where the pin hole leak was located, the plastic was so thin it just melted away. This was not a problem on other locations where I was doing my testing of the product. My only concern is whether Poly-Weld is fuel resistant. Instruction say not to use it on gas tanks/cans because of the flame heating so it's hard to tell. Thanks to Ozhoo I got the new tank which was actually 30% heavier than my old one and had a much better fit and finished appearance. So my fuel leak is fixed. That's the good news. The bad news is I am still not getting oil to flow from the feed tube opening.

If I remove the crankcase check valve and feed air pressure into the hole that leads to the oil tank, oil flows just fine. I ordered a NOS check valve even though the old one passed the "sucking" test. That didn't help. I am testing the saw with the bar removed and clutch removed. I ran it for a minute or so on high and nothing came out. Oil tank was full. Am I doing something wrong with this test method? I did figure out my "bent pin" thingy. If you look real close at the exploded parts list page 3 you will notice what looks like a "line" called out as item "11". This is described as "Pin - Oil Tank Vent". If the bar were installed this pin area would be covered up. Could that be the issue with my testing? Any thoughts are welcome. I'm at my wits end.

 

[Toyboy]

Is the gasket good where the engine check valve is? A new one should have come withe the NOS check valve you bought.

 

[Rich Purdum]

Is the gasket good where the engine check valve is? A new one should have come withe the NOS check valve you bought.

Gasket is good on the NOS part. It was in the sealed package. The old gasket on the old valve was also good. I started wondering if there is another spot where crankcase pressure could be escaping. It only takes a little bit of air pressure when I test with the check valve removed to get the oil flowing.

 

[Toyboy]

It's such a simple system but heavily relies on containing the pressure built up from the engine. If it can't build & hold pressure it won't work. If your engine check valve & gasket is good, then you have to look downstream from there. There are only two places left, the oil line and oil pump & gasket. One of those have to be bad.

 

[Rich Purdum]

The oil line (tube) has been replaced. There is no "oil pump", it is actually a check valve that only allows oil to flow into the oil line and out to the chain. The functioning of the check valve has been verified by blowing and sucking air. Both gaskets which seal this assembly have been replaced. I have verified that everything "down stream" from the crankcase check valve is functioning. As I tried to explain, I removed the crankcase valve. In the recess where the valve screws in is a small hole which allows pressure to transfer to the oil tank. I inserted one of those "straws" from a WD-40 can into this hole and applied light air pressure from an air compressor. Oil did in fact emerge from the tube as it should. I don't know how much pressure the crankcase develops when the saw is running but I only applied a little pressure from the compressor.

 

[Toyboy]

Sounds like you've covered all the bases. It take pressure to work so somethings not right.
I know it not an "oil pump" but that's how we refer to it. If everything else has been replaced, that's the last place to go. Take it out and wash the foam filter and see if that helps any.

 

[GeorgiaVol]

Have you tried thinner oil? I have heard some of these pulse type oilers can have issues with standard bar oil.

 

[Rich Purdum]

I did pick up a container of Echo oil which seemed to be a bit thinner than the old Stihl product I was using. I have not gone as far as trying ATF after reading about the need to have the oil "cling" to the chain. I guess at this point I'll just tear everything down, retest, reassemble, turn around slowly three times and hope for a miracle. If anyone knows the incantation to the spirit of chainsaw oilers please post. I was having trouble with the oiler on my Stihl and after checking with the tech at Alta Saw in Auburn tore it down and could find nothing wrong, put it back together and it started oiling fine. His comment? Sometime it just happens that way.

 

[Rich Purdum]

Some progress I think. I pulled out the "pump" and verified it's function (getting tired of the taste of chain oil...maybe there is a flavored version?). I also verified the "discharge tube" was not blocked. I removed the foam filter and blotted out all oil..no dirt or debris present. I cut new gaskets from some thicker cork material for the pump and it's cover plate. I also retested the crankcase check valve for proper operation. I reassembled the whole thing and ran a test with the bar off. I was hoping to see oil drooling from the discharge tube. Not a major flow but some evidence of oil being discharged. I then mounted the bar without a chain and ran the saw for about 30 seconds. When I removed the bar there was a fair bit of oil on the bar, both by the upper pickup hole and the lower one as well. I guess without the chain picking up oil it had to go someplace.

So now I need to reinstall the clutch and do a real operational test. My question is how much oil should I expect to see? IIRC, Stihl says to watch for the chain actually throwing oil. It's been so long since I used the XXV I don't know what is "normal" oiling. The owner's manual just wants me to "see" oil on the chain. Any tips here are greatly appreciated.

 

[Toyboy]

Making progress, Great! It will take a bit of time for the oil to push all the air out of the system so be patient. As long as your moving oil your on the homeward stretch. It will eventually start throwing oil as pressure builds. As long as the chain looks wet your good. You'll know for sure after your done using it and don't crack the oil cap. You'll find a puddle under it the next morning.

I've found Husky bar oil has a decent flavor, but I usually get my neighbor to do that test for me.

 

[Rich Purdum]

I'll put things back together and do some trail cuts on some downed limbs at our nearby vacant lot. I'll do this with my "old" bar and chain so if I'm not getting adequate oiling it won't be a great loss. My main task for this little fella is to fell some smaller manzanita that are growing on a steep bank with lots of loose gravel and stuff. It's had enough just to keep your footing much less run a bigger size saw. If things work, I want to swap my original 10" bar out for a 12" sprocket tip and keep this small unit for lighter work. Funny, I tried finding 10" bars/chains but came up empty until I realized this size is for pole saws. I don't see why I can't run a 12" setup for light work.

 

[Toyboy]

I put a new 12" Forester bar on mine that I found on Ebay. Great source of parts for these saws.
Once you get the saw running you'll really like it. I run Stihl synthetic @ 40:1 with E-free gas in all my saws.

I've worked on 5-6 of those saws and it's mostly the carb & fuel line & the oil system. I've never has the problem you've had getting one to work, but I suppose my day will come.
I've also figured out how to repair the engine check valves now.