Dolmar 421 crank seal, bearing removal

[redhawk23]

Hi,
My Dolmar crank bearing and seal design appears different than other saws. First, the crank seals are not sold separately from the bearings, so apparently they’re a unit and are replaced as such. Second, it looks like they can’t be removed from the outside. There are three ‘tabs’ that look like they prevent the bearing from being pulled out (see pic). Does anyone have experience with this?

thanks

 

[redhawk23]

I have apparently stumped the chumps.

 

[BuckthornBonnie]

Modified clamshell design?
I haven’t been into one, yet.

 

[Vintage Engine Repairs]

What does the service manual say?

 

[jltrent]

Have you found parts yet?

 

[Fatherwheels]

Modified clamshell design?
I haven’t been into one, yet.

That's not a clamshell design, its standard split case. I would think the cylinder needs to come off and the case split
to pull the shaft and remove that bearing. Lots of them saws were modded so someone will know how to split them
over on the other site.

Here is how its done on a husqvarna, similar process.


And a home made tool for splitting, be carefull though and don't over do it, use some easing oil.

 

[BuckthornBonnie]

Ahh, yep. I was wondering if it was analogous to Stihl’s 271 saws.
It looks like it’ll need to be split as mentioned above. Is that seal leaking for sure? Is the bearing shot?
Interesting design… not a fan of not apparently not being able to remove and install a seal without a case split.
I’ve split dozens of cases with the Husqvarna-style splitter.

 

[Fatherwheels]

Ahh, yep. I was wondering if it was analogous to Stihl’s 271 saws.
It looks like it’ll need to be split as mentioned above. Is that seal leaking for sure? Is the bearing shot?
Interesting design… not a fan of not apparently not being able to remove and install a seal without a case split.
I’ve split dozens of cases with the Husqvarna-style splitter.

And oddly people don't like the clam shell design, which can be split without special tools.
The Dolmar / Makita EA5600 is a hybrid, clam shell and split case design am told, like some old Tanak saws were.

 

[fordf150]

And oddly people don't like the clam shell design, which can be split without special tools.
The Dolmar / Makita EA5600 is a hybrid, clam shell and split case design am told, like some old Tanak saws were.

nothing like a clamshell.....5600 is vertically split case just like a standard pro model saw. only difference is the case is just the case and it bolts into a plastic chassis. 3601 and 35 are built the same way

 

[fordf150]

350/351/420/421/4300 are vertically split mag cased saws.....you have to split the case and the bearings come out towards the crankshaft counterweights. you can get the seals separate from the bearing but i personally think its a waste of time to pull the bearing out of the case, replace the seal, then reinstall a used bearing

 

[Fatherwheels]

nothing like a clamshell.....5600 is vertically split case just like a standard pro model saw. only difference is the case is just the case and it bolts into a plastic chassis. 3601 and 35 are built the same way

That explains it, someone said different to me, but I couldn't see it from looking in the parts manual,
which showed it how you say, split case but in a chassis similar to how a clam shell sits into a chassis, but not a clam shell engine.

 

[Fatherwheels]

350/351/420/421/4300 are vertically split mag cased saws.....you have to split the case and the bearings come out towards the crankshaft counterweights. you can get the seals separate from the bearing but i personally think its a waste of time to pull the bearing out of the case, replace the seal, then reinstall a used bearing

Might be a good time to send the saw off for some porting, it has to be all torn down anyway.

 

[redhawk23]

So, I ordered the bearing thinking that’s all I needed. What other parts and tools will I need to split the case?
Thanks

 

[Fatherwheels]

So, I ordered the bearing thinking that’s all I needed. What other parts and tools will I need to split the case?
Thanks

If your splitting the case, you will need a new case gasket, a base gasket to fit under the cylinder and the Two seals
that sit one on each end of the crank shaft, probably better changing the other shaft bearing too, and replacing the
needle bearing on the small end of the connecting rod / its the one that the pin goes through and into the piston.
If the muffler gasket is damaged then you need a new of those too, same goes for any seals around the carb.

How do you know the bearing is gone, have you done any pressure tests on the case of the saw to check for air leaks.

 

[redhawk23]

Ahh, yep. I was wondering if it was analogous to Stihl’s 271 saws.
It looks like it’ll need to be split as mentioned above. Is that seal leaking for sure? Is the bearing shot?
Interesting design… not a fan of not apparently not being able to remove and install a seal without a case split.
I’ve split dozens of cases with the Husqvarna-style splitter.

When I pressure tested it air came out. As far as I know the bearing is fine, however I haven’t seen the seal sold separately. I imagine if I’m going to these lengths I should replace the other bearing as well? Other than separating the case, is it a difficult job?

 

[Fatherwheels]

When I pressure tested it air came out. As far as I know the bearing is fine, however I haven’t seen the seal sold separately. I imagine if I’m going to these lengths I should replace the other bearing as well? Other than separating the case, is it a difficult job?

I have never been inside one, its no more difficult than any other saw I would imagine, clean everything spotless before taking it
apart, if you get dirt pieces of gasket or any dust into the bearing on the big end of the connecting rod you will have a hard time
getting it back out, the only way is to keep it clean, because without the tools and knowledge to split the crank, put on a new bearing
and line it all up again correctly and have it balanced you will be in big big trouble. And yes, replace both bearings and seals.

 

[redhawk23]

Whinbush, is the needle bearing you’re referring to number 96, 63, and 64 in the diagram?

 

[Fatherwheels]

Whinbush, is the needle bearing you’re referring to number 96, 63, and 64 in the diagram?

96 is the bearing, it could be fine though, but when your in there make sure,
63 is the piston pin which should be ok, and 64 is the clip that holds the piston pin in place,
a spare on of them would do no harm, get OEM parts, not aftermarket / china parts.
No.66 is the base gasket, I don't know if you can re use them, that is why I mentioned getting a new one.
No.72 is the case gasket, you will need one of those.
I don't know how much work your saw has done, but measure the ring gap when you get the saw apart, if its in spec your ok.
Be careful if there is a key or a key way in the crank whee the flywheel fits on, that it does not cut your new seals during assembly,
put a piece of light tape plastic bag cut to size or other very thin protective film on the key way or any non tapered surface on the shaft
so the seal glides over smoothly, some clean grease or oil will help too.

 

[Fatherwheels]

Whinbush, is the needle bearing you’re referring to number 96, 63, and 64 in the diagram?

@fordf150 can set you up with the parts you need, and advise too.
Also, what was your saw doing or not doing to lead you to investigate and find an air leak.

 

[redhawk23]

Thanks for the info. I’ll have too google measuring a ring gap, this all new to me.
Is the same tool used to split the case used to close the case?