066 air leak

[PES+]

Oops

Check your fuel filter and fuel line as well before you tear into the carb

 

[68kaiser]

i put a new fuel filter in while working on it so that should not be a problem. the fuel line is in good shape. now that i think about it may be the tank vent...

 

[PES+]

Double check the fuel line

They can get soft and collapse and pinch shut. Also double check the new filter I have had new filters that were so restricted they would not allow enough fuel through. To check the vent try running the saw on it's side with the cap loose

 

[RiverRat2]

According to the specification section with regard to pressure test, and vacuum test values both Crankcase pressure and vacuum values are .5 bar or 7.25 psi The Stihl service Manual for 064/066 Pressure test says" block off exhaust with sealing plate, remove carb, set piston @ TDC, (checked through inlet port) Fit test flange in place of Carb, Note: making sure lower pin on test flange is fitted in and seals impulse hose. The test gauge must indicate a pressure of .5 bar (7.25 psi) IF THIS PRESSURE REMAINS CONSTANT the Crankcase is airtight. However if the indicated pressure drops,the leak MUST be Located. *Note no reference to time limit on pressure test.

Vacuum: If the vacuum reading remains constant or rises no more than .3 bar
(4.25 psi) within 20 seconds. However if the pressure continues to rise (reduced vacuum in crank case), the oil seals MUST be replaced, even if no leaks were detected in the pressure test.

That is not exactly verbatim, but it is real close

 

[PES+]

Right........now

He said the vacuum passed that test. I discussed this years ago with Stihl reps.....the crankcase is never pressurized when running. So the funny part here here is the two things stated are contradictory

 

[RiverRat2]

Sorry guys sounds like you are already on to it, I think it is fuel delivery related, A Carb kit with a good cleaning & fresh filter and she ought to runopcorn: opcorn:

 

[PES+]

The pressure test is only for quick check

Like if the seal is really blown or the base gasket is leaking you can hear it sometimes it is part of the factory quick assesment

 

[68kaiser]

well today i tried to find a carb kit locally and no shops carry a kit for the walbro. i guess I'm the only person in the valley with a 66 :monkey:.
well i guess i have to call baileys, i love ordering from them but i always spend more than i was originally planning.. thanks for all the help i will get a carb kit and get back to you.

 

[Lakeside53]

He said the vacuum passed that test. I discussed this years ago with Stihl reps.....the crankcase is never pressurized when running. So the funny part here here is the two things stated are contradictory

The crankcase pressures alternates between pressure and vac on each stroke - that's how the carb pumps gas via the impulse line.

Personally, I don't like to see ANY rise in pressure on vac test... or drop in pressure at all.. 100% for a long time or find out why...

 

[PES+]

We need a split hairs smiley

T into you pulse line and see.:biggrinbounce2: it actually never goes much if any over atmospheric pressure and pumps from vac to atmosphere.

I doubt you can tell with a manual guage swinging around though

 

[PES+]

I might be a bit off

I need to find some old texts I have.......somewhere
It does depend on the porting and scavenging arrangement

 

[PES+]

I agree and I also go for no drop however

That little leakage may be in his test set up and his saw symptoms do not reflect that small a leakage problem
It should start and have poor idle or hunt (slowly climb) at idle if that were the case

 

[68kaiser]

just replaced the fuel pickup line in the tank and it made no difference so i can rule that out. :bang:
and i did a another vac test with a gage at the impulse line and one at the spark plug hole. brought it up or should i say down to pressure and no drop in 20 sec on ether gage. i watched it for a few minutes and it dropped very little.
now i am waiting for a call back on a carb kit....opcorn:

 

[Lakeside53]

T into you pulse line and see.:biggrinbounce2: it actually never goes much if any over atmospheric pressure and pumps from vac to atmosphere.

I doubt you can tell with a manual guage swinging around though

You can't T in with a mechanical gauge - the gauge will only average the swings, and typical idle is 2500 times per minute... You need to use a pressure transducer/data logger.

 

[PES+]

Kaiser

You never did say
did you replace both seals?
and check your base gasket

 

[Lakeside53]

just replaced the fuel pickup line in the tank and it made no difference so i can rule that out. :bang:
and i did a another vac test with a gage at the impulse line and one at the spark plug hole. brought it up or should i say down to pressure and no drop in 20 sec on ether gage. i watched it for a few minutes and it dropped very little.
now i am waiting for a call back on a carb kit....opcorn:

You are probaly safe on your seals and gaskets then.

 

[PES+]

Doesn't the 066 have a dedicated pulse line to the carb?

Doesn't the 066 have a dedicated pulse line to the carb?
I use a storage peak hold meter with a pressure transducer for certain work
have used storage scopes for other

 

[PES+]

I won't ask

I won't ask why you check vacuum at the sparkplug hole
Did you check compression after you put on the new jug and piston?

 

[68kaiser]

the only seal that i have not looked at is the one behind the fly wheel but the pressure test was almost rock solid, i tested it for 5 min @ 10 p.s.i.
the vac test is also very solid so i don't think i need to take the flywheel of to inspect it.
one thing that i just noticed after running it is a lot of raw fuel in the muffler. :monkey:

 

[PES+]

Oye

Where are your mixture screws set?
Have you rebuilt a carb before?