Stihl 028 oil pump leak

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Dusty dingo

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Hello,
I have a couple of 028's (bought one new in '81 but it got stolen a while ago) and on one, the AV WB with brake, I have a messy black oil being thrown around inside the brake/oil pump cover. It then seeps out the bottom as well, coming around the clutch drive gear cover (round metal plate around the pto shaft hole). It's not nice clean chain oil! It's really black and messy. I am attaching a pic of the cover and where the oil appears to be escaping (?). The hole in the center of that gear appears to only go a little ways, and is only about the size of a small paper clip. Does this gear just slide on to the shaft below, or a friction fit? Or is it put on with more force than that? Will they separate without damage (the gear and shaft to the pump)?

The pump gear doesn't want to pull out more than about 1/4", with turning and pulling moderately,
not forcing it. It turns very easily, also the oil is delivering to the chain bar ok.
It's just the mess I want to fix!
I can't pull anything further to see behind it all with the pump gear not pulling out to get to the screws.

There is BLACK oil (not nice clean bar oil as it is on the bar oiling hole)coming out from the tiny center hole in the pump gear shaft (see pic with the oil streak coming down the side of gear). You can pull the gear out a bit and push it in a bit, and the oil seems to be coming from the little 'pumping' back and forth like that, however, it also comes out when you run the saw with clutch turning, just seeps out a little at a time, but obviously ads up a lot to make the mess!
stihl-028-oily-cover-jpg.1235884




stihl-028-oil-pump-leak-jpg.1235885

I did a major choke cleaner and air cleanout of the housing behind and around the clutch, brake and oil
pump area!

I don't think this is normal! My other 028 has no brake, and also stays dry in that area.
Can you give me some thoughts on the above issues, and what I can do to make it right?

Last, I am needing to know if there is an oil pump overhaul kit, with seals and hoses? I don't find it anywhere if there is.



I hope this posting displays properly! We shall see :)

Thanks for your time and advice!
Dusty
 
That's quite a bit of oil, my 038 has a very similar pump, if not identical, it is definitely dry there on mine. I would pull the pump off, there is a little o ring between the pump and the case, and also a gasket right under the o ring if I remember correctly. I'd start with checking them. I have to ask, are you saying you got it that clean with just choke cleaner and air? I've pressure washed cases and not been able to get them that clean.
 
To pull the oil pump worm gear, gently lift and turn clockwise which is opposite direction. It should spin out. Some worm gears are solid one piece plastic. Other have a metal screw friction pressed on to back of the sprocket.
Let me know if that works.

LoveStihlQuality
 
Mwmx54 said:
That's quite a bit of oil, my 038 has a very similar pump, if not identical, it is definitely dry there on mine. I would pull the pump off, there is a little o ring between the pump and the case, and also a gasket right under the o ring if I remember correctly. I'd start with checking them. I have to ask, are you saying you got it that clean with just choke cleaner and air? I've pressure washed cases and not been able to get them that clean.
Click to expand...

Thanks for your input!
I'll get a chance to engage with this in the next day or so, and see what I can make happen.
On the cleaning, I know what you mean, that bar oil is some sticky stuff. Well, I did most of the cleanup with carb/choke cleaner spray, didn't take a whole lot, just to loosen
up the crud and flush out with hot water. The finishing touch maybe I need to share with y'all .. it's what I have found to work quite well in most cases, as a final cleanup of that thin film so hard to remove. I am using the very expensive product called Awesome Orange Oxygen citrus cleaner, cost a bank busting $1.00 at the Dollar Tree stores!!
:clap:, for a large spray bottle. You can get refills in maybe a 24 oz or larger, for same price!! I love that stuff for around the shop, even works around the kitchen stove area, so easy to clean up after it with a hot wet rag or just rinse it off. It will take a chain saw exterior from greasy fingerprinted and grime to squeaky clean. I use a soft brush on the outside after spraying it down, or a parts brush inside to get a bit more agressive.

Give it a try and let us know what you think :laughing: :)

The thing I don't like with pressure washers is it forces stuff in places I don't really like it to go.

I'll post on this thread how it goes with the pump project. I won't quit it until I lick it! :)

Cheers
Dusty
 
LoveStihlQuality said:
To pull the oil pump worm gear, gently lift and turn clockwise which is opposite direction. It should spin out. Some worm gears are solid one piece plastic. Other have a metal screw friction pressed on to back of the sprocket.
Let me know if that works.

LoveStihlQuality
Click to expand...

Thanks for the info!
It helps to know which direction one is supposed to apply the twist and pull to! I wasn't thinking on that angle, but now that I do it makes sense, that it must go against the direction the clutch gear would turn it, or it would always be trying to back it out.
And I have looked under the plastic gear, and can see a metal shaft going down to the pump, it has vertical splines going up into the plastic gear.
So at least, I'm pulling on metal not plastic! :yes:

I'll post again my progress or lack of it!
Thanks again
 
The worm and the gear are supposed to stay together, it pulls up/out in one piece. Just rotate it while lightly lifting with a small flat screwdriver.
large_965_wormgear038.jpg
 
Mwmx54 said:
That's quite a bit of oil, my 038 has a very similar pump, if not identical, it is definitely dry there on mine. I would pull the pump off, there is a little o ring between the pump and the case, and also a gasket right under the o ring if I remember correctly. I'd start with checking them. I have to ask, are you saying you got it that clean with just choke cleaner and air? I've pressure washed cases and not been able to get them that clean.
Click to expand...

I am posting an update to the current state of this exploration of the source of my behind-the-brake/pump-cover-mess, at end of this thread. Thanks for your valuable input! :)
Dusty
 
HarleyT said:
The worm and the gear are supposed to stay together, it pulls up/out in one piece. Just rotate it while lightly lifting with a small flat screwdriver.
View attachment 496491
Click to expand...

I am posting an update to the current state of this exploration of the source of my behind-the-brake/pump-cover-mess, at end of this thread. Thanks for your valuable input! :)
Dusty
 
Stihl 028wb oil pump disassembled 2.JPG Well, that was a long 'day or two' :surprised3:,
But the 'project' is at decision time, since all your experienced input served perfectly! The trick I was getting hung up on was (from no prev. experience) I was not
sure how much pressure I should be exerting on the pulling up on the gear, not knowing what exactly was the anatomy below. But your advice to pull firmly up while twisting CLOCKWISE (I think I was twisting back and forth, not realizing it had to back out of the gear below on the pump shaft) and I think it was the rubber seal (actually a real lipped shaft seal, not just 0-ring) that was holding onto the shaft, which once I pulled firmly up and clockwise (counter to gear rotation while running!)
it slipped past and up and out.
Just reiterating the above in case someone else reads this thread with similar doubts like mine! :dizzy:

So now here's my decision: I cannot rationalize the condition I now see in the pump , to result in that black oil oozing from the pinhole in the pump gear shaft, which is what seems to be causing the mess inside that brake cover.
My pump shaft has NO seals on it, (diagram above does not show one either) which would prevent any oil from bypassing the pump shaft in the housing, working it's way up under the Drive Gear shaft, and out the tiny hole in the end of the shaft, which then slings the oil around the outside (see pic above on my first post) of the gear, around the brake area.
There is a thin fiber seal under the drive gear shaft (#10 in the diagram above), which is simply a friction washer, looks new. And the pump housing SEAL (#12 in diagram) which goes around the outside of the gear head (directly under the large plastic drive gear) would do nothing to prevent oil coming up inside the gear shaft mounting spindle which is where the oil has to be coming from, as the pic above shows!

So here's my deduction which maybe someone knows the answer to:
The pump shaft (#16 in diagram above) feels plenty tight, no 'wobble' or wiggle when pushed around at the open end. It also has to be 'tugged' out and won't just drop out, seeming to suggest it is not very sloppy in there. Now, I suppose it's possible for the bore to be worn around the shaft (the shaft shows no wear), allowing excessive oil to bypass the shaft and reach the gear and drive area, overloading that chamber and finding it's outlet by going up the inside of the gear shaft and out that little hole!? (however, when I pulled the gear out, I didn't observe that chamber being loaded with oil, just generally black and messy).
Q: Is that area behind the pump supposed to be lubed by oil bypassing the shaft?
Q: If not, being a dry area, would a dab of lithium grease on the plastic-to-metal gears, be a one-time lube that doesn't need supplementing?

So if nothing above seems to be the culprit, I'm thinking what would be wrong with just putting a plug of JB Weld over the hole on the shaft end, where the oil is finding it's way out?? Maybe they have that for allowing the drive gear shaft to move down over the mounting spindle, and not be air trapped, but is it really that important?

Sorry to make such a project out of this, but hopefully this thread will consider all these issues for others down the road:happybanana: :).

So here's the pics too, of my parts :clap:
Stihl 028wb oil pump disassembled.JPG
 
Do you think someone was using used crankcase oil for bar oil? A little bit of that filth goes a long way. Was the gasket behind the pump in good condition? If it was run with the brake on, it would generate some metallic looking goop, vs just oily residue from clean B&C oil.
 
Dusty dingo said:
View attachment 498109 Well, that was a long 'day or two' :surprised3:,
But the 'project' is at decision time, since all your experienced input served perfectly! The trick I was getting hung up on was (from no prev. experience) I was not
sure how much pressure I should be exerting on the pulling up on the gear, not knowing what exactly was the anatomy below. But your advice to pull firmly up while twisting CLOCKWISE (I think I was twisting back and forth, not realizing it had to back out of the gear below on the pump shaft) and I think it was the rubber seal (actually a real lipped shaft seal, not just 0-ring) that was holding onto the shaft, which once I pulled firmly up and clockwise (counter to gear rotation while running!)
it slipped past and up and out.
Just reiterating the above in case someone else reads this thread with similar doubts like mine! :dizzy:

So now here's my decision: I cannot rationalize the condition I now see in the pump , to result in that black oil oozing from the pinhole in the pump gear shaft, which is what seems to be causing the mess inside that brake cover.
My pump shaft has NO seals on it, (diagram above does not show one either) which would prevent any oil from bypassing the pump shaft in the housing, working it's way up under the Drive Gear shaft, and out the tiny hole in the end of the shaft, which then slings the oil around the outside (see pic above on my first post) of the gear, around the brake area.
There is a thin fiber seal under the drive gear shaft (#10 in the diagram above), which is simply a friction washer, looks new. And the pump housing SEAL (#12 in diagram) which goes around the outside of the gear head (directly under the large plastic drive gear) would do nothing to prevent oil coming up inside the gear shaft mounting spindle which is where the oil has to be coming from, as the pic above shows!

So here's my deduction which maybe someone knows the answer to:
The pump shaft (#16 in diagram above) feels plenty tight, no 'wobble' or wiggle when pushed around at the open end. It also has to be 'tugged' out and won't just drop out, seeming to suggest it is not very sloppy in there. Now, I suppose it's possible for the bore to be worn around the shaft (the shaft shows no wear), allowing excessive oil to bypass the shaft and reach the gear and drive area, overloading that chamber and finding it's outlet by going up the inside of the gear shaft and out that little hole!? (however, when I pulled the gear out, I didn't observe that chamber being loaded with oil, just generally black and messy).
Q: Is that area behind the pump supposed to be lubed by oil bypassing the shaft?
Q: If not, being a dry area, would a dab of lithium grease on the plastic-to-metal gears, be a one-time lube that doesn't need supplementing?

So if nothing above seems to be the culprit, I'm thinking what would be wrong with just putting a plug of JB Weld over the hole on the shaft end, where the oil is finding it's way out?? Maybe they have that for allowing the drive gear shaft to move down over the mounting spindle, and not be air trapped, but is it really that important?

Sorry to make such a project out of this, but hopefully this thread will consider all these issues for others down the road:happybanana: :).

So here's the pics too, of my parts :clap:
View attachment 498108
Click to expand...
Looks good!

LoveStihlQuality
 
Duane(Pa) said:
Do you think someone was using used crankcase oil for bar oil? A little bit of that filth goes a long way. Was the gasket behind the pump in good condition? If it was run with the brake on, it would generate some metallic looking goop, vs just oily residue from clean B&C oil.
Click to expand...
I ran into this with one of my customers and that was exactly what he was doing--even poured in used cooking oil on occasion that he was getting "free" from a restaurant. The mechanism would then get so hot that it smoked after running, even with no load. I flushed the whole oiling system, added fresh bar oil, and it all worked fine--without smoke.
 
Duane(Pa) said:
Do you think someone was using used crankcase oil for bar oil? A little bit of that filth goes a long way. Was the gasket behind the pump in good condition? If it was run with the brake on, it would generate some metallic looking goop, vs just oily residue from clean B&C oil.
Click to expand...

Well, I hadn't thought of the previous user's choice of oil, and that sure could make that black mess. All I know is when i got the saw, it had clean b/c oil in it, but the oil in the pump gear area would take a long time to flush out, wouldn't it. So I will leave that as one possibility. Re the brake on, that sucker really locks down, and I don't see any discoloration of any parts in there, so I'm gonna say it likely wasn't.
And the gasket looks fine, nothing came off on pump, and looks well sealed.

Thanks for scratchin' your head with me :)
Dusty
 

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