Topic: 1948 Evinrude Sportwin fuel tank expansion bulb

This topic has 4 replies, 3 voices, and was last updated 4 years, 7 months ago by VanFleet.

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May 26, 2020 at 3:46 pm #204067
VanFleet
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I have a 1948 Evinrude Sportwin 3.3hp model 4423. There is an expansion bulb that has cracked in the bottom of the fuel tank. (Part 202205 on the catalog page I uploaded) It is my understanding that this bulb prevents pressure from building in the tank. I am unable to find a replacement for this part and was wondering if any member may have a NOS one of these parts or if anyone has a fix for this? I was considering just putting a permanent plug in the hole where the bulb goes. Any advice is welcomed, thank you! 🙂

P.S. I’m a new forum member here so if I’ve done anything incorrectly please reach out and allow me to fix it.
- This topic was modified 4 years, 7 months ago by Mumbles.
May 26, 2020 at 6:47 pm #204083
Buccaneer
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US Member
With the expansion bulb and retainer in place in the tank, is it leak free?
I can’t tell how the retainer is constructed.
Strange affair for sure!

Prepare to be boarded!
May 26, 2020 at 8:35 pm #204096
Mumbles
Participant
Welcome aboard VanFleet and you did OK for your first post here!

It’s a mystery to me why they put these in the tank as the tank is vented via a small copper tube which is a similar design to the Zephyrs of the time. To find that part it’s probably best to place a want ad in the free classified section here. I bought a tank off Ebay once and there should be lots of them out there. Whether it’s needed or not is anyone’s guess and I don’t see why the motor wouldn’t run right if it wasn’t there.

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VanFleet
May 28, 2020 at 1:29 pm #204232
VanFleet
Participant
Buccaneer, the retainer is a press fit metal ring piece that presses against the inside lip of the rubber bulb. In my photos, I didn’t have the expansion bulb fully inserted. However, it does leak fuel with the bulb and retainer installed. It is split and cracked from spending its life of over 70 years installed in the tank. That’s why I removed it 🙂
May 28, 2020 at 1:32 pm #204233
VanFleet
Participant
Mumbles, thanks for the advice on the classified section here. I may look into posting there in the near future. First I think I will try patching the hole with a flat piece of rubber and the retainer clip. A fellow member on Facebook said he had been running one of these motors for a while with the hole welded shut (he bought it that way) and has had no problems while running it.
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