replacing seals ...

[Molecule]

What's the best way to pull the crankcase seals?

In replacing seals, do I need to pack the insides with anything special? Do I need to use a sealant or loctite on the outside?

And, lastly, what's the best way to press the new ones back in?

 

[jimbo1490]

I'm assuming you are talking about changing seals without splitting the cases. Seals don't have a whole lot of "interference" with the case. They can generally be pulled out with a small hook shaped tool made of tool steel. There is a purpose made seal puller for this, though those are usually for the larger sizes of seals like you'd find in an auto engine rather than a chainsaw. The hook in one of those pick sets may work. Press the new seals in with a deep socket of the appropriate size. Seals 'cock' easily so be careful to keep the thing straight as you tap it in.

Jimbo

 

[jimbo1490]

On the question of sealant, most modern shaft seals are coated on the outside rim with an extrudable sealant so you don't have to put anything on them. Back in the old days the outer rim was bare and had to be coated, usually with Form-a-Gasket, non-hardening. When you get the new seals, if they have a grey or green 'paint' on the outer rim, that is the sealant compound. You can still use the above if you want. It won't hurt but you don't need it.

Jimbo

 

[thompson1600]

Are you asking because you need to do this one time on your own saws, or because your looking at being able to change saw seals more often? My answer is different depending on what your looking for.

Tom

 

[Molecule]

thanks jimbo ...

In one of the search threads, I saw where someone suggested using a screwdriver the sides of the tip of which had been filed to a pointed spade and then the tip bent, but I couldn't figure where they inserted it ... between the seal and the case, but aiming toward the seal casing, to crunch the "near" side of the casing and reduce its effective circumference thereby allowing it to drop out ... or ... across the shaft and thru the rubber to the far side, to lift the seal up by the lip, working around the seal to eventually lift it up bit by bit-? Either one sounded like it might untrue the machining of the casing. Another idea which I kind of likes, was drilling two small holes in opposite sides of the casing and inserting two long self-tapping screws, which could then be grabbed with a std. puller.

Makita wants $50 for their seal puller ... pretty cool design (screws into the casing rim and pulls out against the shaft) but it was way too much money, for this saw. (it has a few trees left in it, but the lower bearing on the crank sort of feels a little sloppy -- main journal bearings are tight up-down, front-back and in-out with no movement whatsoever, but the two rod bearings, (probably more of the lower one) has slight .1mm tap-tap in it when lightly rocking the flywheel from cw to ccw rotation, any position of the piston.)

 

[Al Smith]

I use a hook shaped tool on the end of a slide hammer[homemade],and put a very light coating of blue lock on the outer portion of the seal,#2 permatex ,works well also.I have a whole drawer of seal drivers,but most of the time they don't work on chainsaws,so I use a deep socket ,or piece of pipe,to drive them.

 

[TonyM]

I usually pierce the the metal of the seal with a small scredriver and use the hole to pull or pry it out, being careful not to damage the bore or shaft or bearing underneath. I assume all the discussion of a hook shaped tool is for the same purpose.

 

[Molecule]

Tom ... one of my own saws, but not in the sense that I cherish it, so just the simplest procedure using the simplest tools.

Looks like making myself a sharp pointed screwdriver, maybe 1/8" at the tip and 1/4" at the shoulders, and pressing-tapping in a 45° hole straight in from the outside of the bearing wall, basically following the 1mm champfer on the casing straight into the bearing. Then use that hole, and maybe a small piece of wood as a fulcrum, to lift that side of the bearing out. I imagine it might take more than one pressing.

 

[thompson1600]

I've tried the drill a small hole and use a sheet metal screw so you could pull them out and that worked. Just be careful you don't go in too deep and hurt the bearing races.

I think the bent screwdriver should work fine. Just be careful not use the case or the crankshaft as a lever to pry with. You can chip the case or scratch the crank so it won't seal properly.

I agree with others to make sure you get them going in straight, I've done some where I didn't and then it just doesn't seal.

Tom

 

[Ax-man]

I have drilled a small hole in the metal part, used a small e-z out to grab the seal, then used a pair of vise grips to hold onto the e-z out and tap up with a hammer to pull the seal out.

To put them in I try to find a washer the same size as the seal, put that on top and then use a deep well socket to drive it in. The clutch side is easy, the flywheel side takes a little imagination sometimes, they are a little trickier to do

Larry

 

[Molecule]

the flywheel side seal is going to be the hard one ...

the metal lip on the seal casing is so small, maybe 1mm overlap, so there isn't room for an easy out or a tap screw. And the outer diameter of the seal is barely larger than the shaft diameter, there's no room come across the shaft. For that one I rekkon I'll need a small insertion tool, maybe file out small hooks into the sides of two small screwdrivers or maybe old hex keys.

would it be easier to start with cutting and pulling out the rubber, leaving the metal casing behind. is that possible?