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‘38 Olds - Water Pump Bypass Seal


cron1984

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Good evening,

Engine rebuild on my 38 olds 6 is almost complete and I’m in need of a rubber seal for the water pump bypass. I believe the part number is 408500 but I have no idea where to find one. 
I’ve checked most of the normal sites (fusick, etc) without luck. I came across something similar on eBay but the part number is different and it has a slightly different look. 
Flathead 6, 230 cubic inch. 
If anyone has any guidance/leads it would be greatly appreciated. Thank you. 
chris. 

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I came up with different part number, group # 1.099 Seal, water pump by-pass rubber part # 408300, maybe other GM cars used same part.

 

@Gary W maybe Gary if he stops by can shed some light on this.

 

Bob

 

EDIT:  fits 1937 thru 1941 6 & 8 Oldsmobile 

 

Edited by NailheadBob
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I hope Gary offers some guidance - His elaborate write up for his 37 Buick was the inspiration for me restoring my grandfather’s car! Once this thing is done I’ll share some details, but I can promise it won’t be as thorough as Gary’s thread. 

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A water pump bypass.  My '37 Buick doesn't have a water pump bypass, but we do have a system where the cold water will bypass the

radiator and continue circulating throughout the block to warm up faster:  With the thermostat closed (cold water) the water pressure from the pump will overcome the spring pressure of the bypass valve and all the water is shunted not through the radiator but through the block. This condition is called "Recirculation" in the manual.

When the water warms, the thermostat begins to open, allowing water to enter the radiator and thus there is no more pressure keeping the spring valve open.  The spring pressure closes the bypass valve and normal radiator/block circulation begins.

 

 

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From the '37 manual.  

 

Here are a few photos of my water pump.  I don't know if they will give you any information about your bypass.

 

 

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I tried to get a shot from all sides.  

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