Stihl 024AVS Oil Pumps - types and conversions

[itwonder]

As I recall, my 024AVS used about 3/4 tank of bar oil for every tank of gas when it was new. The last few years, it pumped less and less, to where now it's just a trickle. Thanks to a search of this site, I found information to remove the pump, and clean out everything. This pump looks very different from others that are pictured on the site. It is not adjustable. I can feel a slight vacuum on the inlet when I spin it, and a few drops of oil put in the inlet get pushed through to the outlet, so is the pump working? The pin does not go all the way through the case of this pump, so I see no way to drive it out and disassemble the pump. The worm gear is perfect. The oil hose from the tank is not soft, and filter is clear. There was no debris in the tank. The outlet hose is clear ,and is not cracked. I cleaned the little vent hole with spray carb cleaner, and noted it has a check ball inside. Could that have been hung up shutting down the vent? I noticed in the IPL that there are 3 different pumps shown, a 0.50 mm stroke, a 0.65 mm stroke, and one that is adjustable with "Conversion Kit" PN 1121 007 1043. My pump, pn 1121 647 0400, is not shown. Could I or should I retrofit the adjustable pump to replace mine and how much is that part? Is the AVS pump I have known to be problematic? I can get a 026pro pump reasonable; could I retrofit that using a new worm gear? At this point I am thinking of replacing the tank hose assembly so I am sure there is a good seal between the pump and that hose, and putting it back together. Is there anything else I can do?

Thanks,

Bob

024AVS oil pump

Oil tank hose

Diagram

 

[Lakeside53]

It's $100+ to convert to the adjustable pump - the clutch drum has to change also. It only works if you have hole iin the case for the adjuster (the AVS should have). Are you sure your worm isn't stripped?.

Your pump is the very old type, which is why you don't see it on the current IPL.

I'd just put a used 026 0.65 pump on... maybe $20...

 

[itwonder]

Thank you for your suggestions. I took pictures of the case . I'm not sure if it has the required hole for oil pump adjustment; there is a square shaped hole that can be reached from under the saw through a gap, but is that right hole?
This saw is around 1987 vintage.

I took afew shots of the worm gear. The only thing I see is what looks like light scoring on the inside. I can't figure out how it could have gotten there; thought maybe gear is slipping on shaft, but I see no way that could happen. Clutch was very tight. Maybe they are just machining marks.

Is the 026 6.5 pump you suggested a fixed rate pump? Do you by chance have the PN or a pointer to an 026 IPL?

Thanks,
Bob

 

[Lakeside53]

Item 15 on your IPL is the correct later model (plastic) 0.65mm stroke pump.

If your case has the oil adjust indicator stamped (around a round hole) into the flat bottom portion, you can upgarde. If not, the adjustable pump will not fit. I doubt a 1987 case is the correct type.


Pump failure is rare. Try squirting carb cleaner into the inlet, then some light oil. Rotate the gear by hand (many turns) and see if it will move the oil to the outlet. The pump does come apart.. but you have to wreck the pressed insert on the end.


An airleak around the inlet hose mount (hose flange is distorted) will often appear like a pump failure..

 

[itwonder]

Pump failure is rare. Try squirting carb cleaner into the inlet, then some light oil. Rotate the gear by hand (many turns) and see if it will move the oil to the outlet.
An airleak around the inlet hose mount (hose flange is distorted) will often appear like a pump failure..

Now that I know the pump will tolerate carb cleaner, I will give it a good cleaning and then move some oil through it as you've suggested. I will buy a new suction hose to rule out any issue with the flange.

Everything I've checked has seemed very clean in the system, no obvious reason for the issue. One thing I'm suspicious of is the vent. I cleaned it by shooting carb cleaner and then compressed air through it from the outside into the tank. Seems to be clear. Do those ever have a tendency to plug up and cause this kind of problem? Should I replace it?

 

[Lakeside53]

The vents are pretty reliable, but do plug now and then. if you can shoot air throigh it into the tank, it's working..

 

[NHCowboy]

#Resurrect... helping a buddy fix his 024, via video/messenger. What drives this oiler bushing? Friction to the crank?
It was disassembled prior to my super expert assistance.

 

[John Wagstaff]

As I recall, my 024AVS used about 3/4 tank of bar oil for every tank of gas when it was new. The last few years, it pumped less and less, to where now it's just a trickle. Thanks to a search of this site, I found information to remove the pump, and clean out everything. This pump looks very different from others that are pictured on the site. It is not adjustable. I can feel a slight vacuum on the inlet when I spin it, and a few drops of oil put in the inlet get pushed through to the outlet, so is the pump working? The pin does not go all the way through the case of this pump, so I see no way to drive it out and disassemble the pump. The worm gear is perfect. The oil hose from the tank is not soft, and filter is clear. There was no debris in the tank. The outlet hose is clear ,and is not cracked. I cleaned the little vent hole with spray carb cleaner, and noted it has a check ball inside. Could that have been hung up shutting down the vent? I noticed in the IPL that there are 3 different pumps shown, a 0.50 mm stroke, a 0.65 mm stroke, and one that is adjustable with "Conversion Kit" PN 1121 007 1043. My pump, pn 1121 647 0400, is not shown. Could I or should I retrofit the adjustable pump to replace mine and how much is that part? Is the AVS pump I have known to be problematic? I can get a 026pro pump reasonable; could I retrofit that using a new worm gear? At this point I am thinking of replacing the tank hose assembly so I am sure there is a good seal between the pump and that hose, and putting it back together. Is there anything else I can do?

Thanks,

Bob

024AVS oil pump

Oil tank hose

Diagram

I to have this pump ending 0400, mine has a damaged pump piston, can i upgrade to a later pump "

 

[wcorey]

I'd just put a used 026 0.65 pump on... maybe $20...

Is the 026 6.5 pump you suggested a fixed rate pump? Do you by chance have the PN or a pointer to an 026 IPL?

Item 15 on your IPL is the correct later model (plastic) 0.65mm stroke pump.

 

[Joecass]

I have the same problem going on with the same non adjustable pump. I replaced the inlet filter with the line and blew though the out let line also the vent is working and its not clogged. Should I upgrade to the adjustable one? I would have to drill a hole in the bottom of my saw to git it to work.

 

[Whitey88]

#Resurrect... helping a buddy fix his 024, via video/messenger. What drives this oiler bushing? Friction to the crank?
It was disassembled prior to my super expert assistance.

Trying to figure out the same rn. Any advice?

 

[stihltech]

Clean all parts and reassemble. If you WANT to modify, go nuts. Probably one of he least problematic oilers Stihl has. Usually a blockage is all that's wrong. New saws may only use 1/2 tank oil to tank of fuel. If it is sharp, it is enough.

 

[BrettS]

Trying to figure out the same rn. Any advice?

#Resurrect... helping a buddy fix his 024, via video/messenger. What drives this oiler bushing? Friction to the crank?
It was disassembled prior to my super expert assistance.

The clutch assembly tightens against the worm drive.