Help with McCulloch pro mac 700 vacuum testing

[brandonstc6]

I have a mcculloch pro mac 700 that I rebuilt and it was running way too fast at idle. I work on saws a lot so I bought a mityvac vacuum tester. I am trying to pressure test the saw. I made a block off plate with a fitting to attach a hose. I cut a gasket to go under the block off plate. I then took a piece of gasket material and punched two holes for the muffler bolts then i put it under the muffler and bolted it down. I then tried to pump up pressure and the needle on the gauge didn't move any. I then sprayed soapy water all over the seals and gaskets and around the cylinder base, and around the compression release and spark plug. I did not see any bubbles anywhere. Am I missing something or doing something wrong? Thanks

 

[backhoelover]

what about the compression release?

 

[backhoelover]

there is a pump housing undet the gas tank. i think it runs the oil pump off comression need to take take off and see. look above oil tank plug under gas tank

 

[brandonstc6]

I sprayed soapy water around it and didn't see any leaks. Tomorrow I will try removing the compression release and plug the hole. If that don't work, then I will check the oil pump but everything looked good there when I had it apart.

 

[backhoelover]

that is the same set up a the 10-10

 

[backhoelover]

this engine is a sump set up there is no case to split. you might have to keep spraying soap water and keep pumping to you need bubbles.

 

[brandonstc6]

that is the same set up a the 10-10

They are almost identical. I have a few pro mac 10-10 saws.

 

[backhoelover]

see the hole in line with compress release and above the muffler have you tried spraying there that is where the com release can leak

 

[brandonstc6]

this engine is a sump set up there is no case to split. you might have to keep spraying soap water and keep pumping to you need bubbles.

I sprayed a lot soapy water. I will keep working on it.

 

[brandonstc6]

see the hole in line with compress release and above the muffler have you tried spraying there that is where the com release can leak

I tried there and didn't see anything.

 

[backhoelover]

did you spray around where the upper hosing bolts to the engine

 

[backhoelover]

here id you need make well find this leak. need to make sure you didnt cut the rubber gasket under the muffler.

 

[backhoelover]

here if you need me

 

[brandonstc6]

did you spray around where the upper hosing bolts to the engine

I did not spray any soapy water there.

 

[brandonstc6]

here if you need me

Thanks for the help

 

[brandonstc6]

I got the compression release blocked off and I checked the oiler and the bolt holes and I cannot find the leak. What else can I do?

 

[backhoelover]

pull the flywheel and points and then fill up you wheel barrow and dunk the saw. i have had to do that before. did you check the oil pump. also need to check the line that is hooked to the mity vac

 

[backhoelover]

i see that you are using gasket material. you really need to be using rubber

 

[backhoelover]

like a old bike inter tube

 

[rwoods]

Check to see if it will hold a vacuum. If you do the dunk test make sure you are ready to run it soon. Dunked one of my PM800s, didn't get back to it soon enough - now needs bearings due to the trapped moisture.

I will point out your thread in the MAC sticky - those guys have yellow blood.

Ron