McCulloch Mini and Small CC Chainsaw's
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This Mac 120 lives again. My first one is a success. I left the Kotex in the fuel tank alone, and didn’t have a carb check valve, so crossed fingers it would be okay. Carb was a hot mess inside, cleaned with Pb blaster, carb clean, and some wires and air. Used a China kit which fit, but not close to the OEM quality. Reused main needle, China one was way long. MDC 15 carb. Runs and oils excellent. These saws are a pita to work on, but they are pretty tough and well made IMO. One has to want to fix em and have patience for sure. If it didn’t run, under the bench it would go.
Going over to my dads to retrieve an abandoned Mac 130. Going OEM/Walbro with this one
So the 130 is a Max 110. Clutch spring and linings broken and there is an old label on it saying leaks oil. Lol, a challenge! I’m gonna look around dads house tomorrow and see if there is another one kicking around and maybe I can make one good one. He had a few of these and never threw anything away.
Mac 110 not max
Stihl 460 bucking dogg, custom!
Gents I have a problem with a couple of the Eager Beavers with the cylinder filling with oil to the point they won’t pull start until it’s cleaned out. Is this a problem with that big O ring at the base of the oil pump or something else? Thanks in advance for the help. Pig
dbm
New Member
My MM 30 is running great but no oil is getting to the bar, I disassembled everything and reassembled it, making sure that air was passing through all the tubes and hoses so I suspect it is the oil pump itself that is not moving oil. What is it that typically fails on the pump is it's simply the O-ring or are there other components that would cause it not to work properly? Just wondering if I should start changing parts or get an entirely new pump if I can find one.
The Max 120 is a beast in the wood once final tuned. Cut about 4 tanks gas, 10 on oil. Hindsight, I wish I had heeded Mark’s advice and waited on a check valve for the carb. I think mine is toast. Anyone have any kits to sell? Should I pull the brass plug or work a new disc in made from diaphragm material? I’ve never replaced a check valve and been running Macs and Homelites for awhile. Lucky. Any help greatly appreciated
No oil at all on the MM could simply be a stuck piston, or a stuck check valve. You will have to remove the front cover and pull the fuel/oil tank off to get at the oiler. Slide the bail off and remove the pump to check the piston and the check valve. I suspect you would find more details in the back pages of this thread.
The Walbro 86-523 check valve kit will work on the MDC but you have to find a 7/16" Welch plug for the MDC vs. the 5/16" that comes with the kit for the SDC carburetors.
Mark
The Walbro 86-523 check valve kit will work on the MDC but you have to find a 7/16" Welch plug for the MDC vs. the 5/16" that comes with the kit for the SDC carburetors.
Mark
Thanks for the info Mark. That helps, I got Welch plugs with the MDC carb kit, I’ll measure and see if there’s a 7/16. I used MacAttacks fuel line suck blow truck removing the high speed needle and there is no resistance.
This is a humble fabrication but I traced a template and the next one will be a closer match to the case. The dog works well and you can really lever the saw into firewood.
I have noticed on 2 mini Macs I’ve disassembled the oil pump clamp is not clamped into the cast retaining nub on the crankcase. One side is, other outside the nub. Is it proper to only clip one side in? Would that affect sealing of the pump o ring? Thanks!
They can be very difficult to get clamped in place properly. As tight as they fit, I would not be over concerned about the o-ring leaking even it the bail was not fully snapped in place. That said, I always make the effort to get the bail properly seated on both ends.
Mark
Mark
dbm
New Member
yup - did that first .. i completely disassembled the oiler (multiple times), blew air through all the hoses and ports, but no luck getting it to pump - nor let oil through once its reassembled. I read there is a non-serviceable check valve in the housing, so maybe that is the culprit. I may have to drop the $40 .. the saw is running great (And now its all clean and shiny after multiple assemble/dis-assembles)
dbm
New Member
I have this problem - how do you get the check ball unstuck ? I
Usually you can free them by spraying carburetor cleaner or brake cleaner down the hole where the piston goes. Spray, install the piston and pump it manually, then put some oil in the inlet hole and work the piston manually to see if it goes down the inlet and out the outlet. You can also use your pressure tester with a piece of tubing slipping over the steel sleeve in the oil pump, it should pass pressure to the outlet, but hole a vacuum if the check ball is working.
They are reported to be non-serviceable but you can pull the steel sleeve out and check, clean, replace the parts as needed, just be sure to measure how far the steel sleeve is pressed into the body of the pump before you take it apart so you can get it back to the proper position.
L-R Pump body, plastic sleeve, spring, piston
L-R Pump body, check spring, check ball, steel sleeve, plastic sleeve, spring, piston
You should be able to see the hole/groove in the bottom of the inlet when the steel sleeve is pressed in to the proper depth.
Mark
They are reported to be non-serviceable but you can pull the steel sleeve out and check, clean, replace the parts as needed, just be sure to measure how far the steel sleeve is pressed into the body of the pump before you take it apart so you can get it back to the proper position.
L-R Pump body, plastic sleeve, spring, piston
L-R Pump body, check spring, check ball, steel sleeve, plastic sleeve, spring, piston
You should be able to see the hole/groove in the bottom of the inlet when the steel sleeve is pressed in to the proper depth.
Mark
Mark,
I have a Zama carb and kit to rebuild. Looking at the IPL, it appears there is a check valve in these as well. How often do you replace them or find them bad?
I have a Zama carb and kit to rebuild. Looking at the IPL, it appears there is a check valve in these as well. How often do you replace them or find them bad?
Also, do you seal the Welch plug with anything like nail polish? Over read some do and some don’t.
I think the Zama uses a screen, similar to the sintered metal "capillary seal" used in some of the flat back carburetors in place of a high speed check valve. I have never had an issue with a Zama carburetor that gaskets & diaphragms did not fix.
I do not use anything on the Welch plugs, just make sure they are properly seated using a suitable size punch.
Mark
I do not use anything on the Welch plugs, just make sure they are properly seated using a suitable size punch.
Mark
