Repairing Walbro Check Valves

[Randall Ward]

I have a Walbro 21-85 off 10-10 McCulloch. How do you remove the check valve?

 

[Old2stroke]

I too have found the carb diaphragm to be too thin so I bonded two of them together with crazy glue to get the right thickness. They seem to stay together so far.

 

[Ax-man]

I concur , interesting thread. It wasn't until threads like this popped up that you could take those main nozzle check valves out of the carb let alone repair them . I have tools like that leather punch also but never realized you could repair a small engine carb with it along with punching holes for homemade gaskets.

 

[Jasonrkba]

I may have to switch to decaf before trying this.

 

[Ax-man]

I hear ya, teeny tiny detail work to fix a check valve. Need a steady hand and sharp eyes to do this.

I need some saws to work on to try out some of this new info that has been surfacing lately here at AS. I have had some time on my hands lately so I have made a few customized tools to work on them but alas no saws to try them out on.

 

[Old2stroke]

If you can't find the exact right punch, you could try this:
https://www.arboristsite.com/community/threads/make-your-own-punches.327240/

 

[Jasonrkba]

Gonna revive this one. I suspect a bad check valve on a walbro HDB thats in my mac 610. Did anyone find a suitable material to use? Do you think thin mylar would work? This is the first time I am going to try pulling one out. Usually I just replace the screen.

 

[Chris-PA]

Stopped in and noticed this thread - I found an old note, and the rubber I used was 0.014” thick. It came from the diaphragm of an old GM charcoal canister purge valve!

I know that’s obscure, but I have a bin full of old vacuum emissions devices and such from back in the day when such things still existed. I thought at least it might help to know what to shoot for.

 

[Jasonrkba]

I made one from plastic. Im not sure if it works yet because the saw is broke all the way down. I used the blister package from a spark plug. I tested the plastic by soaking it in gas for a couple days. It did not warp or change so hopefully it works because it fit perfect. I have to order new seals and my saw budget is blown for a few weeks.

 

[Jasonrkba]

I'm still kicking around ideas for this and think I might have found something that may work. Polyolefin seems to be extremely resistant to gas. So I searched for different materials made from this and heat shrink for wiring came up. It seems to be about the same thickness and is flexible. The larger diameter may stay flat enough to use. I haven't tried my other fix yet which is basically pvc.