Stihl 028 AV Super repair

[Ax-man]

Wow, that is a nice bench

 

[pioneerguy600]

Im thinking the oiler is leaking on the clutch side. Probably oughta check it out while its open, eh?!

Good idea.

 

[acarpenterdad]

Wow, that is a nice bench

Thank you! I love it! Took me 5 months to make, all from ruff sawn lumber, mostly oak and birch.

 

[acarpenterdad]

The oil pump plastic gear is broken. Ill tear into the pump soon and see whats happening there.

 

[pioneerguy600]

I believe I have mentioned that oil pump drive setup is a bit problematic, new parts will make it good again. Lift and turn the nylon gears, they will sort of screw out.

 

[PogoInTheWoods]

The oil pump plastic gear is broken. Ill tear into the pump soon and see whats happening there.

Which gear? I've also included the IPL if you don't already have one.

​

 

[PogoInTheWoods]

Here's the service manual. A hair too big to attach directly.

https://drive.google.com/file/d/1WgGRLKpL1iV3pVZXEDNh7dEJ-0bCAao6/view?usp=sharing

 

[acarpenterdad]

Which gear? I've also included the IPL if you don't already have one.

View attachment 753055​

Its #45

 

[acarpenterdad]

These are all the parts i need to get'er going. My thinking on the carb is to just buy a new one. Seeing as that is very likely the problem. Could it be anything else?

 

[acarpenterdad]

I believe I have mentioned that oil pump drive setup is a bit problematic, new parts will make it good again. Lift and turn the nylon gears, they will sort of screw out.

This gear has like a fine spline that fits on the pump. The pump and gasket are good.

 

[acarpenterdad]

heres my plan. i'll get the spur gear and chain sprocket, put it all back together, and then do a pressure test. i'd block the muffler and put a fitting on the carb block to attach the mityvac to and clamp the hose shut on the gas tank vent. that should tell me if the carb boot or the gas line or impulse line is the culprit eh?

 

[HarleyT]

No. The pressure test is just concerning the crankcase.

 

[PogoInTheWoods]

edit: Correct. (Missed your post while rooting around for pics in mine.)

Fuel line and tank vent aren't part of the vac/pressure test itself and can be tested separately. Simply pinching off the fuel line at the filter end and applying some pressure from the carb end will obviously test the fuel line. If it holds, remove whatever you used to clamp it off and then pressurize the tank. Should hold some pressure if the vent is working correctly. Should also allow vacuum to easily be drawn. Just ensure the tank is dry when doing a vac test or you'll fill up that nice new MityVac with fuel!

Here's a redneck intake blockoff plate with an injection point for use when the impulse passage is routed through the carb mount bulkhead. Otherwise I just use the impulse hose for the injection point and a solid blockoff plate. For the 028 you could just use a piece of innertube between the carb and intake for a seal and use the impulse hose for your injection point. Same for blocking the exhaust..., a piece of innertube between the muffler and exhaust port.

​

Could also use a spark plug adapter and a solid blockoff plate if the impulse passage goes through the bulkhead and straight to the carb. Here's a store bought Husky version that also functions as a piston stop.

​

Here's a redneck version made from busting off the top of a spark plug. LOL

​

 

[acarpenterdad]

edit: Correct. (Missed your post while rooting around for pics in mine.)

Fuel line and tank vent aren't part of the vac/pressure test itself and can be tested separately. Simply pinching off the fuel line at the filter end and applying some pressure from the carb end will obviously test the fuel line. If it holds, remove whatever you used to clamp it off and then pressurize the tank. Should hold some pressure if the vent is working correctly. Should also allow vacuum to easily be drawn. Just ensure the tank is dry when doing a vac test or you'll fill up that nice new MityVac with fuel!

Here's a redneck intake blockoff plate with an injection point for use when the impulse passage is routed through the carb mount bulkhead. Otherwise I just use the impulse hose for the injection point and a solid blockoff plate. For the 028 you could just use a piece of innertube between the carb and intake for a seal and use the impulse hose for your injection point. Same for blocking the exhaust..., a piece of innertube between the muffler and exhaust port.

View attachment 753278
​

Could also use a spark plug adapter and a solid blockoff plate if the impulse passage goes through the bulkhead and straight to the carb. Here's a store bought Husky version that also functions as a piston stop.

View attachment 753280
​

Here's a redneck version made from busting off the top of a spark plug. LOL

View attachment 753281​

1st and 3rd pic is what i envisioned making! i never really thought about testing the lines individually! i can do the boot the same way as well. thanks!

 

[acarpenterdad]

I've ordered the spur gear and chain drive. Will be about a week.

 

[acarpenterdad]

I tested the carb Boot, fuel line, and impulse line. No leaks. Still waiting on parts.

 

[acarpenterdad]

I'M BAAAAAAAACK! starting to clean and put things back together. the handle, carb, boot, impulse line, and flywheel are on. hopefully with this 3 day weekend i can get'er dun and see how it runs.

 

[acarpenterdad]

edit: Correct. (Missed your post while rooting around for pics in mine.)

Fuel line and tank vent aren't part of the vac/pressure test itself and can be tested separately. Simply pinching off the fuel line at the filter end and applying some pressure from the carb end will obviously test the fuel line. If it holds, remove whatever you used to clamp it off and then pressurize the tank. Should hold some pressure if the vent is working correctly. Should also allow vacuum to easily be drawn. Just ensure the tank is dry when doing a vac test or you'll fill up that nice new MityVac with fuel!

Here's a redneck intake blockoff plate with an injection point for use when the impulse passage is routed through the carb mount bulkhead. Otherwise I just use the impulse hose for the injection point and a solid blockoff plate. For the 028 you could just use a piece of innertube between the carb and intake for a seal and use the impulse hose for your injection point. Same for blocking the exhaust..., a piece of innertube between the muffler and exhaust port.

View attachment 753278
​

Could also use a spark plug adapter and a solid blockoff plate if the impulse passage goes through the bulkhead and straight to the carb. Here's a store bought Husky version that also functions as a piston stop.

View attachment 753280
​

Here's a redneck version made from busting off the top of a spark plug. LOL

View attachment 753281​

i've got access to a bridgeport at work now so i can see lots of fittings and doodads in my future.

 

[acarpenterdad]

Here she is running after everything is done. If i lower the idle or low speed carb screw, it dies. Any thoughts or comments?

 

[HarleyT]

Well, it idles without the chain turning.
What is that wire by the spark plug wire?