266 Crank seals?

[robfromaz1977]

I have pulled my hair out trying to get one of my 266's to stay running. Put new fuel line and filter, carb rebuilt and still it will only fire and die immediately. If I feather the throttle it will try to run and will run at WOT. Tried adjusting the carb to match my other 266 and no matter what I do nothing helps. Checked the seal on the clutch side and looked fine. I even have a new one for that side. Have not tried pulling the flywheel yet because in need some bolts for my puller. Tried running it on its side and opening the fuel cap thinking the vent is plugged but it still wants to die. If the seal behind the flywheel is bad could it make it run like this? Sorry if this has been covered somewhere here before but I just don't have the time to do a search. Thanks.

 

[lone wolf]

sounds like it although check fuell line for a slight crack then do a pressure - vac test.

 

[Meadow Beaver]

What does it have for compression?

 

[robfromaz1977]

How do you do a pressure-vac test? As for compression it was 125.

 

[lone wolf]

How do you do a pressure-vac test? As for compression it was 125.

125 is bare minimum if you get it sealed up tight i would get a meteor pist assembly from baileys.buy a mitivac 8500 vac/ pressure tester seal the intake and exhaust ports you need to make steel plates and drill holes to bolt them on put a piece of bike inner tube as a gasket to seal it off.does your saw have an impulse line if so plug your tester into that if not need to do some kind of fitting on one of the plates .don't give up there are videos ask bl snelling for help. any questions?

 

[lone wolf]

125 is bare minimum if you get it sealed up tight i would get a meteor pist assembly from baileys.buy a mitivac 8500 vac/ pressure tester seal the intake and exhaust ports you need to make steel plates and drill holes to bolt them on put a piece of bike inner tube as a gasket to seal it off.does your saw have an impulse line if so plug your tester into that if not need to do some kind of fitting on one of the plates .don't give up there are videos ask bl snelling for help. any questions?

oh yea have you tried another carb?

 

[robfromaz1977]

oh yea have you tried another carb?

Thanks for the help. Maybe I should turn this into a project saw. Yes the carb on it is one I bought a while back and finally got around to putting a kit in it. The saw ran the same before with the old carb so I think I can rule that out.

 

[robfromaz1977]

Just an update on my 266 with low compression. I got bored the other day and decided to take the carb off of my good 266 and put it on the 266 that wouldn't run. Low and behold it ran and ran good. It turns out that the carb I bought to replace on the bad 266 was no good. Don't know what is wrong with it but I tried it on the good saw and it would do the same fire up and die instantly thing my bad saw would do. So I dug out the carb I took off of the bad saw and put it on the good saw and it would run some but only if I turned the low jet way to far out. Turns out the only thing wrong with that carb was it was sucking air around the gas line fitting. I had broken the brass fitting off a while back and tried replacing it with a plastic piece of vacuum tee. I decided to try and remove the brass fitting from the bad carb and was able to get it out without any damage. I put it in the carb that had the plastic piece and now the saw runs right. I feel a little stupid for not catching the problem sooner but now I have both saws running again.

 

[spudulike]

Just for the record, classic signs of bad crank seals is that on standard factory H & L carb settings, the idle speed can't be brought down to typical idle speed with the idle adjuster screw - it races and can only be slowed by richening the mix.

This is caused by the weak mixture from air being let in past the faulty seal - very much the same as the effect of the saw speeding up at idle when you are about to run out of fuel.

There you go - my words of wisdom for the day

Spud

 

[lone wolf]

Just an update on my 266 with low compression. I got bored the other day and decided to take the carb off of my good 266 and put it on the 266 that wouldn't run. Low and behold it ran and ran good. It turns out that the carb I bought to replace on the bad 266 was no good. Don't know what is wrong with it but I tried it on the good saw and it would do the same fire up and die instantly thing my bad saw would do. So I dug out the carb I took off of the bad saw and put it on the good saw and it would run some but only if I turned the low jet way to far out. Turns out the only thing wrong with that carb was it was sucking air around the gas line fitting. I had broken the brass fitting off a while back and tried replacing it with a plastic piece of vacuum tee. I decided to try and remove the brass fitting from the bad carb and was able to get it out without any damage. I put it in the carb that had the plastic piece and now the saw runs right. I feel a little stupid for not catching the problem sooner but now I have both saws running again.

so it is running good and holds an idle well

 

[robfromaz1977]

Just for the record, classic signs of bad crank seals is that on standard factory H & L carb settings, the idle speed can't be brought down to typical idle speed with the idle adjuster screw - it races and can only be slowed by richening the mix.

This is caused by the weak mixture from air being let in past the faulty seal - very much the same as the effect of the saw speeding up at idle when you are about to run out of fuel.

There you go - my words of wisdom for the day

Spud

Thanks for the wisdom. Now if I could only remember some of it. I may have to write it down somewhere.

 

[robfromaz1977]

so it is running good and holds an idle well

Yes it is just like it's supposed to be. I even ran it in a 16" piece of spruce and it cut like I would expect it to, really well. I have gone out and started it a couple of times when it was cold just to make sure I didn't just dream I fixed it. I still might pull the jug and see if a new piston would be a good investment for it but for now I will run it as is.

 

[spudulike]

Glad it turned out ok in the end - always satisfying when the site brings back a saw from the dead.

Spud