Jonsereds 621 crank case seal leaking fuel, any fix?

[rlamppa1]

Just picked up a very nice 621 that has been sitting for years. I had initially purchased it for parts to keep my dad's 621 running a few more years. After cleaning the carb and putting a new gas line and filter, it started on 3 pulls. Very good runner. The problem is it appears to be leaking gas from the tank from the main gasket between to 2 halves of the crankcase. Does anyone have an extra gasket laying around they would be willing to part with, or can I use some silicone gasket maker like 3 Bond and mate them back together. Any thoughts would be greatly appreciated.

Regan

 

[Cantdog]

Just picked up a very nice 621 that has been sitting for years. I had initially purchased it for parts to keep my dad's 621 running a few more years. After cleaning the carb and putting a new gas line and filter, it started on 3 pulls. Very good runner. The problem is it appears to be leaking gas from the tank from the main gasket between to 2 halves of the crankcase. Does anyone have an extra gasket laying around they would be willing to part with, or can I use some silicone gasket maker like 3 Bond and mate them back together. Any thoughts would be greatly appreciated.

Regan

Welcome to the site Regan. Don't use silicone....quite a bit of work to split the cases and replace the gasket. Gaskets are very hard to come by....best solution is the make a new one which is also quite a task but doable. You definitely need a gasket between the cases halves.

 

[rlamppa1]

Thanks for getting back. Do you recommend a specific type of gasket material to use? Or how thick of material? It doesn't leak a lot, but it will make a mess if gas is left in it after using.

 

[Cantdog]

Thanks for getting back. Do you recommend a specific type of gasket material to use? Or how thick of material? It doesn't leak a lot, but it will make a mess if gas is left in it after using.

I would just get a roll of gray gasket material from NAPA. Should be about 1/16" thick. Have you tried tightening the case bolts yet?

 

[rlamppa1]

yes. I tried snugging them up today. They turned a hair, but pretty snug. I was hoping the gasket would swell up after a week of having gas in it, but no such luck.

 

[Cantdog]

yes. I tried snugging them up today. They turned a hair, but pretty snug. I was hoping the gasket would swell up after a week of having gas in it, but no such luck.

Yeah......that's to bad. Definitely worth a try. How clean is the tank inside?

 

[rlamppa1]

The tank is pretty crusty looking. When I look in the tank of my Dad's it is still like new with all the red paint on the inside. This one doesn't have much paint left and has a lot of scale on it. I rinsed the tank out with fresh gas several times before I tried starting it. No real debris came out of it. Another thought is if the tank is sort of "eaten" up, could I find some type of gas proof epoxy and mix up and coat the inside of the tank. If something like that would work, it would probably be fine for many years that way. Having this saw run is bonus to me, I had bought it more for parts in the first place. If I do split it apart and everything is pitted, maybe all the work to do it and the new gasket wouldn't help? Thanks for your replies.

 

[Cantdog]

The tank is pretty crusty looking. When I look in the tank of my Dad's it is still like new with all the red paint on the inside. This one doesn't have much paint left and has a lot of scale on it. I rinsed the tank out with fresh gas several times before I tried starting it. No real debris came out of it. Another thought is if the tank is sort of "eaten" up, could I find some type of gas proof epoxy and mix up and coat the inside of the tank. If something like that would work, it would probably be fine for many years that way. Having this saw run is bonus to me, I had bought it more for parts in the first place. If I do split it apart and everything is pitted, maybe all the work to do it and the new gasket wouldn't help? Thanks for your replies.

Yeah that's why I asked....a lot of these old saws have sat with fuel in them for years and they have serious corrosion in the tanks. How does the saw look in general? Is the paint in good shape and no crack in the top cover? The silver paint was very thin from the factory and is generally gone.

 

[rlamppa1]

It’s real clean. What do you think of the epoxy idea?


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[Cantdog]

It’s real clean. What do you think of the epoxy idea?View attachment 813390


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Yep that's dandy looking! I usually wouldn't do a sealer on a saw but if you could get it clean enough it probably would work for awhile. The problem is getting it clean enough to seal properly......oil and gas love to creep under the edge of patches. I think what I would do is try it and then keep your eye out on ebay for a decent crankcase complete that is in as good condition.....they come up now and then...usually $40-460. Then you could move all your good stuff onto that platform. Really not to hard to do....and wouldn't as much work as splitting your cases.

 

[rlamppa1]

Sounds like a plan. Thanks for the help. This could turn into a bit of an addictive hobby.


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[rlamppa1]

If I go that route, the only question I have is how does the Oiler come out? Take out the hex nut and grab it with needle nose and pull it out? Thanks


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[KASH]

I have fixed quite a few metal gas tanks with rusted out holes with epoxy.I am sorry I cant give you the name cause its gone from the tube.I also sealed the seam on a Husky 162 metal tank.the expoxy comes in a clear plastic tube about the size of a fat cigar the expoxy is round and fits in the tube you cut a piece of the expoxy and roll it in your fingers until it is mixed and then apply .I usually rough up the area it grips really well.I have 3 621s great saws the last 621 had the red paint in the tank,Here in Ontario Canada I use real gas but I went across the border to Minnesota and got a can of gas it removed all the red paint in the tank. I burned the rest of the can in my truck served me right for being cheap
Kash

 

[KASH]

That looks like a real low hour saw even has the spark plug cap.Very very few 621s have it left.
Kash

 

[Cantdog]

Sounds like a plan. Thanks for the help. This could turn into a bit of an addictive hobby.


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Ya think?? LOL!!!

 

[Cantdog]

If I go that route, the only question I have is how does the Oiler come out? Take out the hex nut and grab it with needle nose and pull it out? Thanks


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More or less......take out the hex plug and unscrew the adjuster all the way out and remove then find the proper thread bolt of sufficient length to stick out of the case an inch or two and thread that into the pump body then either pull or if it appears stuck lever the pump body out by clamping vice grips on the bolt and prying against the case...perhaps padding the leverage point on the case with a small block of wood or similar.