Dolmar 421 crank seal, bearing removal

[redhawk23]

One seal was leaking and the saw wouldn’t hold pressure. I think my original problem was gas related as it happened with my new saw and an acquaintance had the same problem with gas from the same small town gas station.
Would it be idiotic to put it together with a leaking seal considering I don’t think it was causing the problem of starting and stopping?

 

[link]

One seal was leaking and the saw wouldn’t hold pressure. I think my original problem was gas related as it happened with my new saw and an acquaintance had the same problem with gas from the same small town gas station.
Would it be idiotic to put it together with a leaking seal considering I don’t think it was causing the problem of starting and stopping?

If you know you have a faulty crank seal - then you need to replace it. Never heard about that on a young saw such as yours though.
I have repaired a Jonsered 50cc, probably from the 70's, and you might find it at a Stihl 025 that looks like it had been at world war 2.
Those saws are basically used up, so much everything inside is worn out. It doesnt sound like a Dolmar 4 series though.

 

[LenchiCRO]

Hi all, problem with makita ea4300f same model as dolmar in topic. The chain saw starts , but on pull on throttle and dies. New carb and same. I try new ignition same. I tried the throttle with chain brake and it seem better..hmmm. Then i removed the clutch , put some gasoline on seal and poled starter rope and see bubbles. video attacht. my conclusion, saw wont rev up due to deficit crank pressure . therefore not getting enough fuel through ports. Thoughts?

 

[LenchiCRO]

 

[Tomos770]

You are correct....if seals are not sealing....there is no impulse (or impulse is weaker) to the carburetor....so carburetor is not pumping (enough) fuel into the cylinder....

There is more...if you are able to start a chainsaw with defected bottom end seals....it will quickly seize itself due to lean burn conditions inside the cylinder ( gasoline burns hotter due to too much air).….