Have you tried with a new o-ring?

 

Never mind. Looks like no longer available. Guess some sealant would be only option.

 

Is it like about 1/16 of an inch? If you search o-rings on McMaster with a 0.070 width, there are many in large diameters that might match up.

 

My industrial catalogues show "make a o-ring" kits.
My understanding is you cut to length then glue it together. (super glue?)

Has anyone used these kits?

If the o ring is OK maybe a small amount of coolant safe rtv in the o ring groove would seal it.

Are the electric water pump suppliers providing new o rings?
Would they sell one outside of the kit?
Edit:
Meziere Enterprises Sku: WPG118

O-RING For WP118 and WP118HD

Our line of cooling system products currently includes items such as: electric high flow water pumps, cooling system accessories, recovery tanks and radiators.

www.meziere.com

 

From a quick search:

The parts CD shows a seal, water pump cover (O-ring) 11508805.

GM #10128329

I am not sure which is correct.
Edit many references to GM #10128329

My cheap HF calipers say the pump diameter the "O" ring needs to fit is 3.565" and the ring is .100" thick (round)

IIRC the O ring does stretch slightly to fit so 3.560" should be fine

3 - 9/16" overall diameter; one hundred thousandths thick. Roger.

Dash 153 by my observation. Cost is $0.24 for two in the 70 durometer nitrile.

The cork seal?

that seal is a cork holds that cover on damn tight. That leads me to believe that seal is doing its job. However, not all OEM/GM re-popped pumps have this seal on it.

There's a very thin o-ring in there that's supposed to seal it. Should I augment with something

A smear of rtv on the cover may work.

 

Hi, is this the part ?

http://oemcats.com/oem-parts/10128329.html#google_vignette

 

WP cover O ring

 

Have made O rings , yes

Have an local Seal- O ring warehouse that almost always comes up with what I need .

Sealing Solution Group - Fluidseal Inc.

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www.sealsonline.com

Hylomar would be my go to for a questionble sealing O ring I was stuck with.
Non hardening and fuel proof too