066 air leak

[68kaiser]

i got my new piston and jug on and did a pressure test and the damn thing is leaking from the crank seal behind the clutch and oil pump "%$@* &*#@ !&#"

can this be fixed without taking the whole saw apart? before i tore the thing down i don't think it was leaking it was running and idling fine.
.......just my luck...thanks

 

[Lakeside53]

You don't need to take the saw apart - just the flywheel needs to come off.

It's a real pain to get the seal out without the correct puller though, and it's easy to damage the magnesium bore that the new seal has to seat into. You might consider taking it to your dealer and paying him a nominal sum to remove the seal for you. Make sure you don't put the new seal in too deep, and be sure to grease the lips before insertion.

 

[68kaiser]

thank you lakeside. i wish you did not say to take it to the local stihl shop thou, i went in there a while back to feel them out and the test was this, the saw had a .404 rim sprocket on it and i told them i wanted to run 3/8" chain and i asked the man behind the counter how much it would cost to convert it over and he quoted me $50 to do it, and that was all he told me. i was disappointed to say the least.

 

[CaseyForrest]

I had seals in a 460 and an 066 done at the dealer. Each time it cost me $25 for both seals and labor. Not bad at all.

 

[68kaiser]

o.k. i got the new cranck seal in, air tested and i had it to 10 p.s.i. had a smoke, half a beer checked and it dropped the thickness of the needle in the gage "1/16'' of an inch. so i thought i was in good shape so i assembled the saw and started it......... it will start up, run ma-by 5 sec then blu blu blu dead.
lakeside said not all leeks show up on a pressure test so how do i put vacuum on the case, i have a gage for it but how to i put the suction to it?
any other suggestions would be great I'm about to take a hammer to the &*%$ thing.. thanks...nick.......

 

[bama]

I hooked up my tester(design from CaseyForrest) with a vacuum. I used a lot of tape and mated it to the end of the hose.


http://new.arboristsite.com/showthread.php?t=32356&highlight=vacuum+tester

 

[68kaiser]

did a vacuum test it holds -7 in hg to -6 1/2 in hg for 14 sec. so i lost 1/2 in hg in 14 sec. what is acceptable and how do i find the leak when it is on a vacuum test?

 

[bama]

Someone correct me if I am wrong, but I think it needs to keep at least half its vacuum in 30 seconds.

 

[68kaiser]

i just took the jug off and reassembled and checked the impulse while the case was open checked again but this time i used the clock on the wall to time it instead of my head it is holding -7 to -6 1/5 for 30 sec. it is falling at the same rate as before i just count slow.

 

[bama]

That sounds good to me, but I would get someone with more experience, like Lakeside, to verify that it is acceptable.

 

[PES+]

Try spinning the crank slowly under test

Sometimes a seal has a hard time with a scratch or burr on the crank and will seal while stopped but not with the crank spinning.
You do not have to spin it past compression and you can rock it both ways I caught a couple of weird nics on the crank face that way in big Stihls.

You may have a carb problem like a plugged screen or bad diaphram.

I am still trying to figure out how you can change the PTO/clutch seal only by taking off the flywheel on any saw

 

[68kaiser]

i don't know either, i think it was a misprint by lakeside but i knew what he meant and got it done from the clutch side. i will try turning the crank while testing to see what happens.

 

[rupedoggy]

PEST thanks for asking that question. I don't think you can change the seal behind the oil pump by taking off the flywheel either. Mike

 

[PES+]

Get out the spray bottle

Get a spray bottle and fill it with water and a little dish detergent and take off the flywheel and spray the mag seal, the cylinder to case joint, the exhaust plate and the intake boot and look for the bubbles. Only check this way under pressure (obviously) Your leak doen iesn't bad per say but it whould have none

 

[PES+]

I forgot

Spray your whole test rig too. Mine leak only on the real puzzlers it seems
Murphy lives with me

 

[68kaiser]

i just turned the motor while under vacuum and did'nt find a "bad spot" that i could see. i did the soapy water thing on everything but the flywheel side. under pressure it was almost rock solid i dont think it lost 1/2 pound in 5 minutes, ill give it a try, but are these acceptable numbers

 

[PES+]

Yes acceptable

The saw should run.
When you ran it after the seal repair can you detail how it ran and stopped?

Either carb problems or ignition but not hearing it run it us hard to say which

 

[PES+]

Did you change both seals?

Or just the PTO seal?

 

[68kaiser]

i just got it together- 2 pulls shocked popped, 2 pulls half chock it ran then died. it did not rev up before dieing, i can blip the throttle and keep it going but you can hear that it is not right while doing it.

 

[PES+]

Carb problem

Get a kit and clean and rebuild