Thermostat bypass hole - Chevelle Tech
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post #1 of 33 (permalink) Old Apr 13th, 19, 1:58 PM Thread Starter
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Chris
 
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Thermostat bypass hole

I have a thermostat that looks like this:


where would I drill the bypass hole? I found some EMP ones that have them drilled on the side, would that be correct?


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post #2 of 33 (permalink) Old Apr 13th, 19, 2:25 PM
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Re: Thermostat bypass hole

This is the only picture I found for that type. Not sure if it's correct for this application, but looks like it.

https://www.speedwaymotors.com/Speed...stat,1836.html

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post #3 of 33 (permalink) Old Apr 13th, 19, 2:47 PM
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Re: Thermostat bypass hole

The bypass hole should be in line with water flow. Just my thought.
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post #4 of 33 (permalink) Old Apr 13th, 19, 3:04 PM
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Re: Thermostat bypass hole

You can go here too.
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post #5 of 33 (permalink) Old Apr 13th, 19, 6:59 PM
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Re: Thermostat bypass hole

why not just buy one that fails open? or is there another reason for the bypass hole?
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post #6 of 33 (permalink) Old Apr 13th, 19, 11:57 PM Thread Starter
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Re: Thermostat bypass hole

Quote:
Originally Posted by Jebchevelle View Post
why not just buy one that fails open? or is there another reason for the bypass hole?
I've had 2 fail. Regardless of packaging name, they all seem to come from the same manufacturer. So now I will try a bypass to see if anything changes.

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post #7 of 33 (permalink) Old Apr 14th, 19, 1:58 AM
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Re: Thermostat bypass hole

I use the bypass thermostat to eliminate the bypass hose, I've had good luck with thermostats, but that was awhile ago. New ones maybe different.
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post #8 of 33 (permalink) Old Apr 14th, 19, 5:58 AM
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Re: Thermostat bypass hole

First, unless you are using a race pump that has no bypass, or you have blocked the bypass [ why would you? ] there is no reason to drill holes in the stat. Stewartcomponents.com started the drilled stats because some of their pumps had no bypass.

Drilling the stat will just make the engine take longer to warm up....not good.

If you look at the pic in post #4, at about the 10 o'clock position, you can see the dimple in the rim that that lets the air purge. Once again, no need for holes.

Failures. The problem I have had is that there is a rubber seal on the inner piston that is tight. When new, sometimes the stat won't open because of this. I put some auto trans fluid in there to lubricate it & test it for on/off on the stove a couple of times. Seem to work ok once they have open/closed a couple of times.
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post #9 of 33 (permalink) Old Apr 14th, 19, 8:45 AM
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Re: Thermostat bypass hole

That's a pill thermostat, I had nothing but trouble with them. The Stant Hi flow works the best for me.. I drill a very small hole in my thermostats to keep the stat surrounded in moving water..
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post #10 of 33 (permalink) Old Apr 14th, 19, 9:01 AM
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Re: Thermostat bypass hole

Autozone Hi-flow works for me. Only accurate one I found out of several brands including pill type on a stove. I do drill a small hole for bleeding.
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post #11 of 33 (permalink) Old Apr 14th, 19, 3:37 PM
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Re: Thermostat bypass hole

Small 1/16 hole wherever you can get it to let the air bleed by.


It won't effect warm up time with a 1/16" hole, but the 1/16" hole will help prevent an air pocket
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post #12 of 33 (permalink) Old Apr 15th, 19, 12:49 PM
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Re: Thermostat bypass hole

w/calculated risk. Been using MIlodon hi flows since the 80s, finally had one stick about a month ago probably from sitting too long. It let loose and works fine, gotta drive these things.

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post #13 of 33 (permalink) Old Apr 15th, 19, 1:56 PM
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Re: Thermostat bypass hole

Back in the day, the top shelf thermostat was an all brass 180 degree Robert Shaw unit. Iím not sure if they still make them but I have one in my car and a spare in itís original box on a shelf. ()

I installed a 55GPM electric pump on my car that has no heater hose inlet or manifold bypass hose inlet. Because of that and that Iíll never drive it in the cold, I decided to eliminate the heater lines.

I was concerned that SOME coolant needs to bypass the thermostat upon cold startup, I added a few holes in the perimeter of the thermostat. It seems to work as the engine gets to operating temp fairly quickly and it settles around 180 degrees. Then the fans cycle on & off by the fuel injection system.

I remember seeing holes in a thermostat like I did in some magazine article from long ago. It seems some old tricks still work.
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post #14 of 33 (permalink) Old Apr 15th, 19, 1:58 PM
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Re: Thermostat bypass hole

Quote:
Originally Posted by Gtogeoff View Post
First, unless you are using a race pump that has no bypass, or you have blocked the bypass [ why would you? ] there is no reason to drill holes in the stat.
Naw, some of us do it so all the "burps" of air escape the block much faster. Otherwise the closed thermo blocks escaping air ( high point on engine) . So there is reason #1 anyway. And it makes a world of diff .
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post #15 of 33 (permalink) Old Apr 15th, 19, 6:08 PM
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Re: Thermostat bypass hole

I've never drilled a hole in a thermostat.
I have a feeling that some people do it just because they read that other people did it, not because a hole is actually needed.
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