Stihl 08s carb leak

[kane98]

Need some help on getting this carb sealed up. It’s a Tillotson 166B and it has a slow leak at the atmospheric vent.
went I add pressure to it from about 8lbs down to about 4lbs it leaks down slow then from 4lbs down it leaks slower yet. I’ve tried everything but Durko.. don’t know if you can block off that vent or not. I don’t know what it controls in the carb. I’ve put a new kit in it and made sue that the pump bodies and diaphragm bodies are good and flat as far as I can tell. The pump diaphragm and the main diaphragm and gaskets aren’t leaking are far as I can tell. It just at the atmospheric vent. Any help would be great..

Dale

 

[hotshot]

Did you use the OEM RK94-HL or DG2-HL kit? I’ve seen cheap aftermarket metering diaphragms seep air pressure through at the center button.

Those HL-166B Tillotson carbs are really easy to rebuild, and you should not plug that vent hole nor use Dirko sealer on it.

I’d tear it back down, reset the needle lever height, rub the gasket edges with 2 cycle oil, and try pressure testing it again.

 

[kane98]

It only has there part # on the invoice but it has tillotson HL series manual with so I’m guessing it’s the oem one. It started out leaking from the fuel cover. Then the atmospheric vent but I’ll try what you said and see what happens. The control lever may be a very little bit high but I had to bend it to adjust it down to get it close to even with the metering chamber. Other than that everything else I think is spot on.

 

[cscltd]

check it will metering dia off- if doesnt hold pressure- then needle or pump side is issue

if holds then then it could be lever height or metering dia stiff or deformed/bent
a leaking metering dia would still hold pressure as the needle is the stop point for pressure test-leaking metering dia would leak gas in chamber or while its running give issues
-you need the vent, just like vent on gas tank

 

[kane98]

I’ll try it with diaphragm off first and if it leaks. At least if it does leak I’ll know it’s the needle but it sent leaking from that gasket it was leaking from pump gasket where the atmospheric vent is located.

 

[Twinfield]

Have you tried a soap solution or putting in water to see where it’s leaking from.

 

[kane98]

Yes I tried all of those. You won’t believe what it was. I knew after I went thru it twice that it was going to be something easy. The screw that holds the fuel inlet on was broken. When you squirt soap mixer on you soap around the gaskets. I had a leak at the atmospheric vent so I was concentrating on that. It was a bubble every couple seconds coming from that when I put it in water. Until I dropped it in the bucket then I seen it coming from the screw on the fuel inlet cap. I had already checked that but not around the screw. Unbelievable. When I put a screw driver on it, it just split apart. Then I had to drill that out go find another screw. Then still fix the vent. But I got it. I think the control lever was a bit to high so I lowered that and decked the diaphragm body and it held for 10 minutes. Until I took it off.