# Coolant reservoir is non vented at cap how does this work? **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** thermostats\ **Created:** [October 15, 2016, 1:01pm UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101 "2016-10-15T13:01:51Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![lesabre](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/lesabre/32/17221_2.png) [@lesabre](https://community.cartalk.com/u/lesabre)\ **Post date:** [October 18, 2016, 12:17am UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/21 "2016-10-18T00:17:07Z")
yes and your right , it doesn’t even say anything on the cap about do not remove when hot, maybe it just pushes the hot coolant into the reservoir when hot then when it cools off it sucks the coolant back into the radiator … I did notice they routed the reservoir hose way lower than the top big radiator hose .which attaches very low to the reservoir. HHMMMM ? ---
**Author:** ![insightful](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/insightful/32/2732_2.png) [@insightful](https://community.cartalk.com/u/insightful)\ **Post date:** [October 18, 2016, 2:08am UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/22 "2016-10-18T02:08:53Z")
> [@lesabre1](#): > > maybe it just pushes the hot coolant into the reservoir when hot then when it cools off it sucks the coolant back into the radiator … That is precisely what happens. ---
**Author:** ![insightful](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/insightful/32/2732_2.png) [@insightful](https://community.cartalk.com/u/insightful)\ **Post date:** [October 18, 2016, 2:11am UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/23 "2016-10-18T02:11:05Z")
> [@lesabre1](#): > > I did notice they routed the reservoir hose way lower than the top big radiator hose .which attaches very low to the reservoir. HHMMMM ? This makes no difference and does not affect the way it functions. ---
**Author:** ![lesabre](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/lesabre/32/17221_2.png) [@lesabre](https://community.cartalk.com/u/lesabre)\ **Post date:** [October 18, 2016, 4:25am UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/24 "2016-10-18T04:25:52Z")
Thanks so much I think we have it down to a science now . ---
**Author:** ![lesabre](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/lesabre/32/17221_2.png) [@lesabre](https://community.cartalk.com/u/lesabre)\ **Post date:** [November 22, 2016, 1:05pm UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/25 "2016-11-22T13:05:21Z")
your right .insightful ---
**Author:** ![tardrex](https://avatars.discourse-cdn.com/v4/letter/t/34f0e0/32.png) [@tardrex](https://community.cartalk.com/u/tardrex)\ **Post date:** [November 23, 2016, 12:47am UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/26 "2016-11-23T00:47:11Z")
don`t most overflow tanks have an overflow tube/hose? ---
**Author:** ![insightful](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/insightful/32/2732_2.png) [@insightful](https://community.cartalk.com/u/insightful)\ **Post date:** [November 23, 2016, 1:12am UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/27 "2016-11-23T01:12:51Z")
> [@tardrex](#): > > don`t most overflow tanks have an overflow tube/hose? Some do, some don’t. My Insight doesn’t. ---
**Author:** ![Rod-Knox](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Rod-Knox](https://community.cartalk.com/u/Rod-Knox)\ **Post date:** [November 23, 2016, 1:49am UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/28 "2016-11-23T01:49:16Z")
There is always an overflow tube and it would be connected at the pressure relief cap which is often not on the expansion tank. Overflow tanks have no pressure, they are where the overflow tube dumps. ---
**Author:** ![lesabre](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/lesabre/32/17221_2.png) [@lesabre](https://community.cartalk.com/u/lesabre)\ **Post date:** [November 23, 2016, 3:42am UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/29 "2016-11-23T03:42:25Z")
yes on any GM car with a 3800 V6 is what you get no tube coming out to the ground below ---
**Author:** ![lesabre](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/lesabre/32/17221_2.png) [@lesabre](https://community.cartalk.com/u/lesabre)\ **Post date:** [November 23, 2016, 3:42am UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/30 "2016-11-23T03:42:58Z")
nope on any GM car with a 3800 V6 is what you get no tube coming out to the ground below ---
**Author:** ![insightful](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/insightful/32/2732_2.png) [@insightful](https://community.cartalk.com/u/insightful)\ **Post date:** [November 23, 2016, 6:50pm UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/31 "2016-11-23T18:50:30Z")
> [@Rod\_Knox](#): > > There is always an overflow tube and it would be connected at the pressure relief cap which is often not on the expansion tank. Overflow tanks have no pressure, they are where the overflow tube dumps. How is this a “Solution” to a question about an overflow/vent on a reservoir tank??? ---
**Author:** ![lesabre](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/lesabre/32/17221_2.png) [@lesabre](https://community.cartalk.com/u/lesabre)\ **Post date:** [January 28, 2017, 10:54am UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/32 "2017-01-28T10:54:07Z")
I once received an answer that on GM car with V6 motors the closed cap on the tank plastic tank top has a very small relief hole on the side of it so if the resivor plastic tank ever becomes filled to the top it lest it out at that tiny relief hole .⛽ ---
**Author:** ![Rod-Knox](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Rod-Knox](https://community.cartalk.com/u/Rod-Knox)\ **Post date:** [January 29, 2017, 11:48pm UTC](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101/33 "2017-01-29T23:48:04Z")
I ran across this and thought some might appreciate a classic Corvette with an expansion tank. Those Blue Flame 6s were real power houses, guys. [https://www.google.com/search?q=Corvette+Blue+Flame+6&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjEp7P-w-jRAhWHh1QKHbrNDGoQsAQILg&biw=1200&bih=639#imgrc=VHqc82JhmPczHM%3A](https://www.google.com/search?q=Corvette+Blue+Flame+6&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjEp7P-w-jRAhWHh1QKHbrNDGoQsAQILg&biw=1200&bih=639#imgrc=VHqc82JhmPczHM%3A) [Previous page](https://community.cartalk.com/t/coolant-reservoir-is-non-vented-at-cap-how-does-this-work/96101.md?page=1)