Pioneer 620 - Won't rev up clean to full throttle

cdahl383 · Thursday at 9:18 PM

cbfarmall said:
You can use a large punch and work your way around the seal to drive it. As big as it is, you can probably tap directly on it with a ball peen hammer. If you are feeling brave, you look to have enough room to add a small chamfer to that seal bore to ease installation. I know for Poulan 3400 saws this is a must.

Whatever you, if it seems like the seal is starting crooked, stop and try again. Once you distort the seal, it's trash.

Ok cool, maybe I can try that. Just makes me a little nervous striking one side without something supporting the other side. I used a socket to drive in the flywheel seal, but that was a lot easier to do without the shaft in the way.

I started chamfering the outer edge a little bit. I used a little bit of sandpaper to round off the sharp edges. I did that when the old seal was in place as that caught most of the crap. I could put some towel/rags in there at the bottom to catch any junk/shavings if I worked on it more, then just flip the saw upside down and remove the towels.

What would work best for chamfering that edge? Sandpaper is just good for sort of taking the sharp edges off, but not sure that's the best thing to use for doing more than that. I have a small dremel tool with attachments like sanding stones, that could work I guess.

I have a Poulan 3400 too, but luckily it didn't need seals. Just fuel lines, filter, and a few other minor things and I was able to get it up and running. I'll keep that in mind if I ever do the seals on that saw.

I'll take my time with driving the seal in place. Hopefully with some patience I can get it in straight the first time.

cbfarmall · Thursday at 10:13 PM

Just don't strike it, work around the edge and tap it. It will probably try to rock one side up when you tap on the other. Idea is to start it and drive as evenly and square as possible. Nothing wrong waiting till you gather the right tools, though.

Dremel would work well-don't nick the crank. I believe my buddy used his pen knife and scraped a chamfer in the aluminum.

Judging from the picture, that case already has a decent chamfer. I'd leave it alone.

altatim · Friday at 10:55 AM

If you have a 3D printer they are invaluable in making random punches and seal drivers.... Simple cylinders that cost less than a dollar once you have a printer. I've used it to make oddball drivers and weird tools and even the odd part.

cdahl383 · Friday at 3:48 PM

altatim said:
If you have a 3D printer they are invaluable in making random punches and seal drivers.... Simple cylinders that cost less than a dollar once you have a printer. I've used it to make oddball drivers and weird tools and even the odd part.

I've heard a lot about these 3D printers but I have no clue what they are or what they can do haha! Sounds cool. Do you have any photos to share?

cdahl383 · 2025-02-10T16:33:53-0500

Well I attempted to install the seal over the weekend. It was a fail. I picked up a larger socket to drive the seal in. I brought some old film negatives out to the garage and got everything set up. I couldn't get the seal started. I took everything off, greased things up more, then set it back on and started to drive it in. It went in nice and straight, but I forgot to put the film negative back over the crankshaft before I started driving it in. At that point I figured well I can't remove it now, might as well just keep driving it down and hope it goes over the step on the crankshaft. Nope. Part of the oil seal got snagged and lifted up. The seal was trash. At that point I said some choice words and went inside.

I ordered another seal that should be here mid-week. I'll drive that one in using the film negative this time haha! It was really a shame too because I drove the seal in nice and straight, it would have been perfect. Oh well, live and learn. Hope to have the new seal in later this week and then reassemble the saw over this upcoming weekend. Getting tired of seeing all these parts all over my work bench haha!