# Intake manifold heat exchanger, how does it work? **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [March 10, 2020, 7:02pm UTC](https://community.cartalk.com/t/intake-manifold-heat-exchanger-how-does-it-work/160720 "2020-03-10T19:02:04Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![zinophfragment\_163832](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/zinophfragment_163832/32/23435_2.png) [@zinophfragment\_163832](https://community.cartalk.com/u/zinophfragment_163832)\ **Post date:** [March 10, 2020, 7:02pm UTC](https://community.cartalk.com/t/intake-manifold-heat-exchanger-how-does-it-work/160720/1 "2020-03-10T19:02:04Z")
Hi guys So I was looking at diagrams on the Lexus RC F, and I found a little thing underneath the intake manifold (its called the lower intake manifold I think) that houses a heat exchanger. I actually never knew there could be a heat exchanger underneath the main intake manifold. If someone could tell me or show me how it works, I would greatly appreciate it! ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [March 10, 2020, 7:42pm UTC](https://community.cartalk.com/t/intake-manifold-heat-exchanger-how-does-it-work/160720/2 "2020-03-10T19:42:16Z")
A heat exchanger is an inter cooler. It cools compressed air from a supercharger or turbo. Compressed air gets hot. If the HE is under the intake I assume it is liquid cooled. An air cooled HE is usually mounted behind front grille for airflow. ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [March 10, 2020, 7:58pm UTC](https://community.cartalk.com/t/intake-manifold-heat-exchanger-how-does-it-work/160720/3 "2020-03-10T19:58:48Z")
On the RCF it is just an engine valley cover plate with a water outlet. ![RCF Heat exchanger](https://global.discourse-cdn.com/cartalk/original/3X/1/d/1d621bfd349cc26ab3b4be364559d3adee97a972.png) This one is leaking coolant; ![20170104_112625](https://global.discourse-cdn.com/cartalk/original/3X/2/e/2e33654ef8dcbf1791d7370351dc18a0a12c6aab.jpeg) This is what it looks like under the cover plate; ![20170104_131631](https://global.discourse-cdn.com/cartalk/original/3X/4/f/4f1421b19c3d2b4bc4dd52edd05d0b78cb01ff96.jpeg) ---
**Author:** ![zinophfragment\_163832](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/zinophfragment_163832/32/23435_2.png) [@zinophfragment\_163832](https://community.cartalk.com/u/zinophfragment_163832)\ **Post date:** [March 10, 2020, 8:52pm UTC](https://community.cartalk.com/t/intake-manifold-heat-exchanger-how-does-it-work/160720/4 "2020-03-10T20:52:49Z")
Ok, thanks for the pictures! I do have a question however. The coolant exits the ‘valley plate’, and where does it go? And, where does the coolant come from? Is that the primary coolant exit from the engine? ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [March 10, 2020, 9:01pm UTC](https://community.cartalk.com/t/intake-manifold-heat-exchanger-how-does-it-work/160720/5 "2020-03-10T21:01:49Z")
The pipe on the right connects to the back of the water pump. In the last picture, the dark holes are coolant passages to the block on the sides of the cylinders. ---
**Author:** ![zinophfragment\_163832](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/zinophfragment_163832/32/23435_2.png) [@zinophfragment\_163832](https://community.cartalk.com/u/zinophfragment_163832)\ **Post date:** [March 10, 2020, 9:03pm UTC](https://community.cartalk.com/t/intake-manifold-heat-exchanger-how-does-it-work/160720/6 "2020-03-10T21:03:08Z")
OOOH, so the water goes from the lower hose into the water pump, then into the engine valley where it flows into those dark holes, where it then flows around the engine! Am I correct? EDIT: Also, are there drain ports on the left side of the engine? I can’t see any coolant passages on the passenger side of the block from that image. And, on the top of the pipe on the right, there appears to be a mini tube. Is that coolant bypass? ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [March 10, 2020, 9:47pm UTC](https://community.cartalk.com/t/intake-manifold-heat-exchanger-how-does-it-work/160720/7 "2020-03-10T21:47:10Z")
Here is a diagram of the heat exchanger; ![RCF coolant flow](https://global.discourse-cdn.com/cartalk/original/3X/5/c/5c2f5aa49cc297525a5e8bf5c1cbaa7206314058.png) ---
**Author:** ![zinophfragment\_163832](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/zinophfragment_163832/32/23435_2.png) [@zinophfragment\_163832](https://community.cartalk.com/u/zinophfragment_163832)\ **Post date:** [March 10, 2020, 9:51pm UTC](https://community.cartalk.com/t/intake-manifold-heat-exchanger-how-does-it-work/160720/8 "2020-03-10T21:51:42Z")
Ok, but I’m still a little confused about the passenger side coolant passages. In the real life picture, I can’t seem to see any passenger side coolant passages. But in the diagram you have shown, there is clearly coolant passages on the passenger side. And also, where do you get your diagrams from? It might be handy for me. ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [March 10, 2020, 9:58pm UTC](https://community.cartalk.com/t/intake-manifold-heat-exchanger-how-does-it-work/160720/9 "2020-03-10T21:58:24Z")
The passenger side coolant ports are not in view in the picture due to the camera angle, the diagram shows 4 ports on each side (arrows). The diagrams are from Toyota, you would need a subscription to Toyota TIS. ---
**Author:** ![zinophfragment\_163832](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/zinophfragment_163832/32/23435_2.png) [@zinophfragment\_163832](https://community.cartalk.com/u/zinophfragment_163832)\ **Post date:** [March 10, 2020, 10:00pm UTC](https://community.cartalk.com/t/intake-manifold-heat-exchanger-how-does-it-work/160720/10 "2020-03-10T22:00:44Z")
Ok thanks for the help