|
|
Post by heavyhauler on Jun 13, 2019 14:48:19 GMT -5
I have read some threads on pressure testing crankcases and one of them mentioned performing the test with the carburetor mounted on the saw (pyramid reed system), and using the fuel inlet tube on the carb to pressure everything. In other words it would allow you to test carb and crankcase at the same time. I am not seeing how this could work though likely due to my minimal knowledge of chainsaw repair. From what I can tell it seems my best reading would be to remove the carb and reads, seal this end with a way to attach a pressure/vacuum tester and then seal the exhaust port as well. Any thoughts or input? I have plates made from the thread I found here with a homelite bulletin that contained dimensions for them. I also believe I saw a link here to a Homelite service manual that described pressure testing crankcase procedures. I cannot find that anymore either however I could be confused on where I read some of this information as it isn't everyday that I am on here and actually have time required to service and repair an old chainsaw.
|
|
|
|
Post by undee70ss on Jun 14, 2019 0:56:02 GMT -5
I have read some threads on pressure testing crankcases and one of them mentioned performing the test with the carburetor mounted on the saw (pyramid reed system), and using the fuel inlet tube on the carb to pressure everything. In other words it would allow you to test carb and crankcase at the same time. NO! Carburetor pressure testing and crankcase pressure/vacuum testing are two different tests. To pressure/vacuum test the crankcase, intake and exhaust ports must be blocked off. There are a lot of ways to block them, making block off plates, making some custom gaskets, I believe even someone here said to just use gorilla tape. Where you can connect your pressure tester depends on the saw, and what you are using to block ports. On saws with a pulse hose, usually pressure is applied there, on saws that don't use a pulse hose, You can put a fitting on one of your plates, or make/buy a fitting to replace spark plug. Carburetor pressure testing is just testing the carburetor. This can be done on or off the saw in most cases. Most of the time you are just testing to see if needle and seat are leaking. Anymore, I pressure test every carburetor I clean/rebuild before installing. More carburetor tests can be found here. houseofhomelite.proboards.com/thread/5820/homelite-carb-adjusting-pressure-testing |
|
|
|
Post by heavyhauler on Jun 14, 2019 7:07:41 GMT -5
i didn’t think it would work that way. Due to the way I was connecting the pressure tester I decided last night to make a custom solid gasket to block the reeds. We could not build any pressure at all that way. We found that the gasket material (felpro) we used was letting air right through it. In the end we used both of those ideas from that thread. Took the gasket we made wrapped it with gorilla tape and reinstalled it. Built pressure fine and determined crankcase seals were good
|
|
|
|
Post by onlyhomelites on Jun 15, 2019 13:48:44 GMT -5
I bought some 1/8" thick rubber sheet that I cut block-off gaskets from. Because I work on a lot of the same saws, I have been drilling for the bolts and that way it is easy when I need one. The time to install them makes it tempting to skip the pressure testing step, but for diagnosing a lean condition, it can be priceless.
One example was my recent Super XL-922. All indications were a lean condition but once I pressurized the crankcase, I could tell I had no leaks. It turned out to be a stuck governor in the carburetor!
|
|
