066 Pressure test ?

[Bridog]

Hey Guys,
I'm pressure/vac testing my 066. Vac test holds 7.5 with no change for 1 minute. Pressure test drops 1.25 psi (start 7.5psi) in 1 minute. Soap test shows slow bubbles at what looks like the base of the decomp. No other bubbles at intake, impulse, seals, cyl gasket, exhaust and carb block offs. Intake, impulse, decomp all new. Decomp is oem. So I'm confident the leak is at the decomp.

Tried multiple times with same results.

Does the decomp leak of this magnitude harm the saw?
Is it odd that the vac holds firm?
Can a guy take high temp red rtv and coat the threads of the decomp/cyl without any issue?
What is that tiny pin hole in the side of the decomp? Both the new and old one has it.

I'd really like to avoid plugging off the decomp.
Thanks guys. Brian

 

[TheTone]

Try plugging the decomp temporarily and repeat pressure test.

 

[HarleyT]

Take the decomp off and clean it. Reinstall.

 

[HarleyT]

OOOOps, saw it is new... Take it off and look for irregularities.

 

[HarleyT]

It isn't leaking bad enough to be a problem.

 

[Cease232]

Decomps always leak. plug them for the test them replace.


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[ELECT6845]

I hate decomps. Crank it down and see what happens.

 

[Bridog]

Hey Guys, thanks for your help.

I tracked down a plug and put it in. It held pressure rock steady. So alls well with the rest of the saw.

Then I put the decomp back in with a light coat of high temp red rtv on the upper threads and washer. Let it sit for a couple hours and retested. It now holds rock steady.

I'm calling it good and can finish the reassemble when my brake band gets here.

I also bought a can of ford tractor light grey spray paint today to try on the side cover and recoil cover. Man that stuff is a dead match for Stihl grey imo. Covers almost in 1 coat.

Thanks