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Thread: Thermostat

  1. #1
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    Default Thermostat

    Who has drilled holes in it to get
    rid of air bubbles

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    Member Vettehead Mikey's Avatar
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    Many
    people

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    Quote Originally Posted by Vettehead Mikey View Post
    Many
    people
    It sure doesn,t look like it, your
    the only reply.
    Does it really work well and does
    your car get up to temp

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    I'm sorry but the statement that "many people" have drilled thermostats is not true.

    Some do but most don't.

    It is urban legend that drilling thermostats offers any practical improvement in cooling system performance.

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    Not for improvement in cooling system performance. but
    to help purge air from the system

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    You do not need to drill holes in the thermostat to purge air.

    However, if you're really concerned about that during warm up, use this fill method, remove the water outlet and the 'stat. Fill the block until the water level is 3/16-1/4 inch below the water outlet mounting surface. Reinstalll the 'stat and the water outlet. Connect all hoses then fill the radiator.

    Start the engine, allow it to warm to operating temperature. Shut the engine off and allow it to cool an hour. Remove the fill cap and fill the system if the level has dropped.

    If you don't want to go to the trouble of removing the outlet, with the engine cold, fill the system to the full level. Wait 30 min. or so, then check the level, again. Then start the engine. Let it run a a minute or so then shut it off. Check the coolant level and add more coolant as necessary.

    Start the engine again, this time with the cap off. Allow the engine to warm just to thermostat opening, then fill the system to the proper level and reinstall the cap. Allow the engine to warm to operating temperature, then shut the engine off and allow it to cool several hours. Check the coolant level and add coolant as necessary.

    Road test the car for several miles or until the engine reaches operating temperature. Let the engine cool after the test and check coolant level. Any "bubble" should be gone and the coolant should be at the normal level.

    If thermostats for small-block and big-block Chevrolets needed holes to vent air, for the last 55 years, all the thermostats sold would have had noles.

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    Member Vettehead Mikey's Avatar
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    Quote Originally Posted by Hib Halverson View Post
    I'm sorry but the statement that "many people" have drilled thermostats is not true.

    Some do but most don't.

    It is urban legend that drilling thermostats offers any practical improvement in cooling system performance.

    Awful grumpy of late, aren't you? 'Many' is a function of quantity, not necessarily of percentage. I never said most. In either case, you have no more idea of 'how many' actually did than I do.

    To the OP:

    A number of people (quantity to be ascertained by independent authorities) are rumoured to have possibly drilled an alleged hole in their thermostats for the unconfirmed purpose of lessing or eliminating (according to unnamed witnesses) the reported tendency of the engine temp gauge (correct terminology to be confirmed) to temporarily peak shortly before thermostat opening at a purely indicated level that might upset some owners. Or not. Not that there's anything wrong with that. Or right. E&EO.

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    A lot of the "high performance", "super cooling" thermostats have holes in them that allow fluid to circulate even when the thermostat is closed.

    Hib is correct that you do not need to drill holes in order to purge air from the system.

    That will happen over time: fill it up, run it until the thermostat opens, fill it again. Repeat until full.

    The reason I put holes in mine, is because the engine temp would tend to "spike." I have a 180 thermostat. By the time cool fluid was in the block, my temp was 220. By the time the thermostat closed, my temp was down to 150. It would bounce around like this the entire time I was driving (hour long trips).

    I now have a much more stable engine temperature.

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    Quote Originally Posted by minifridge1138 View Post
    A lot of the "high performance", "super cooling" thermostats have holes in them that allow fluid to circulate even when the thermostat is closed.

    Hib is correct that you do not need to drill holes in order to purge air from the system.

    That will happen over time: fill it up, run it until the thermostat opens, fill it again. Repeat until full.

    The reason I put holes in mine, is because the engine temp would tend to "spike." I have a 180 thermostat. By the time cool fluid was in the block, my temp was 220. By the time the thermostat closed, my temp was down to 150. It would bounce around like this the entire time I was driving (hour long trips).

    I now have a much more stable engine temperature.


    Plus
    fill once and you are done

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    Member Vettehead Mikey's Avatar
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    Quote Originally Posted by 1tpi View Post
    Plus
    fill once and you are done
    In all fairness to Hib, he is correct that you will need to check the level in your coolant recovery tank several times after a fresh fill of the system, drilled thermostat or not. It does usually take several stop/start/hot/cold cycles to get all the air out.

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    Quote Originally Posted by Vettehead Mikey View Post
    In all fairness to Hib, he is correct that you will need to check the level in your coolant recovery tank several times after a fresh fill of the system, drilled thermostat or not. It does usually take several stop/start/hot/cold cycles to get all the air out.

    Idrilled mine filled up rad and filled the recovery tank
    a little higher then the line and I have not refilled anything
    one fill and done

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    I'm not going to argue the issue with you "VetteheadMikey".

    A few people drill thermostats but "Most" or "Many" do not.

    There is not practical advantage in doing so, but it will change the engine's warm-up characteristics.

    If there was an advantage, starting in the mid-50s, thermostats for SBCs would have had holes in them.

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    Member Art Jett's Avatar
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    Maybe a dumbazz question but if the thermostat were to stick closed, wouldn't holes aid in the engine not overheating as badly?

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    Thermostat Curtis's Avatar
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    Quote Originally Posted by Art Jett View Post
    Maybe a dumbazz question but if the thermostat were to stick closed, wouldn't holes aid in the engine not overheating as badly?

    Maybe.. depends on how big the hole is. the bigger the extra holes, the slower the engine warms up..

    Maybe a better solution for wide temperature swings would be a balanced thermostat. I got one for 12 bucks and it stopped the wild swings from too hot to too cool and stabilized the operating temperature to 190 F.

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    I always thought the holes were drilled in case of a failure, the thermostat would not fully closed.
    A Proud U.S. Navy Veteran

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