Pressure test - stop leak

[DanAyo]

Now that the crankcase seals have been replaced and not leaking, the pressure applied during the test has increased. As I approach 7PSI the manifold (rubber boot) on the 028WB is starting to leak. I think this is because of the cast in molded “bumps” on the carb side of the intake boot.

The plug fits well and it is sealed with a worn clamp that is placed over electrical tape to eliminate any possibility of damage to the rubber.

Question -
Should I put a little grease on the intake side of the rubber to stop the leak?
Is there a better way to atop this leak?

This site has been a gift to me. I can’t explain how much the help offered by the members have assisted me. I am learning new things daily.
THANKS!
Danny

 

[lone wolf]

Now that the crankcase seals have been replaced and not leaking, the pressure applied during the test has increased. As I approach 7PSI the manifold (rubber boot) on the 028WB is starting to leak. I think this is because of the cast in molded “bumps” on the carb side of the intake boot.

The plug fits well and it is sealed with a worn clamp that is placed over electrical tape to eliminate any possibility of damage to the rubber.

Question -
Should I put a little grease on the intake side of the rubber to stop the leak?
Is there a better way to atop this leak?

This site has been a gift to me. I can’t explain how much the help offered by the members have assisted me. I am learning new things daily.
THANKS!
Danny

Stop the leak for the test or the assembly?

 

[DanAyo]

Stop the leak for the test. Once the saw is assembled I see no reason why the carb manifold will leak. It is sealed on the outside rubber of the flange.

 

[lone wolf]

Stop the leak for the test. Once the saw is assembled I see no reason why the carb manifold will leak. It is sealed on the outside rubber of the flange.

Try grease and see.Very heavy.

 

[DanAyo]

I’ll post the results.

 

[TheTone]

Try grease and see.Very heavy.

Yep. The interior bumps (there to cause turbulence and better fuel/air vaporization) go up close to the manifold and often cause tiny air leaks even when a well fitting stopper is used. I use Dow-Corning High Vacuum grease because I have it around, but any heavy grease should work. I never have to use any kind of clamp.

 

[huskihl]

I slip a piece of rubber or duct tape in between the boot and carburetor and tighten the carb down

 

[Benwa]

I personally wouldn't concern myself with the leak you're encountering. It will have no bearing on anything once assembled. If you're trying to get the crankcase to HOLD pressure/vacuum, then I agree with @huskihl 100% I always vac/press test with the tank on and intake boot & carb installed with a piece of rubber between the two. I try and test saws in "as close to normally assembled" arrangement as I can. This also allows the intake boot to be fully tested if you use the impulse line for attachment. Are you concerned with the seals leaking and wanting to know before it's entirely assembled? The tank being on shouldn't change anything. If you don't want to assemble further before testing more, just hit the crank seals with some soapy water/leak check first. At 7 or 8 psi even if it's leaking out the boot, the rest of the crankcase also has the same pressure in it. Mind you, you will have to keep pumping. It won't "hold" the pressure, but if the seals are leaking still, they'll show themselves with the soapy water on them. By the way, keep up the good work!