# Exhaust pressure under valve cover? **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [May 16, 2019, 8:01am UTC](https://community.cartalk.com/t/exhaust-pressure-under-valve-cover/140434 "2019-05-16T08:01:51Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![art1966](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@art1966](https://community.cartalk.com/u/art1966)\ **Post date:** [May 16, 2019, 8:01am UTC](https://community.cartalk.com/t/exhaust-pressure-under-valve-cover/140434/1 "2019-05-16T08:01:51Z")
2004 Camry, 4-cyl (16-valve), 130K miles I posted a few days ago about the oil fill cap’s being left loose after an oil change: > [@Cleaning oily engine](https://community.cartalk.com/t/cleaning-oily-engine/140193): > > 2004 Camry, 130K miles. (Drop-down menus are not letting me select make/model.) Amazing! On oil change last Wednesday, Trusted Independent Mechanic left the oil fill cap loose. I guess that explains the exhaust noise that sounded like it came from the engine area, and the exhaust smell in the passenger compartment. (I had assumed it was an unfortunate coincidence – how could an oil change cause an exhaust leak?) There is a moderate bit of oil sprayed around the engine. What process or produ… I discovered the loose cap because, immediately after the oil change, I heard exhaust sound from engine compartment and had exhaust smell coming into passenger compartment. Now, in the middle of the night, I suddenly realize that maybe the oil fill cap (in the valve cover) should not have exhaust pressure behind it. Asking you experts is easier than doing internet research. Is it normal to have exhaust pressure there, or do I have a problem? ---
**Author:** ![COROLLAGUY1](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/corollaguy1/32/7575_2.png) [@COROLLAGUY1](https://community.cartalk.com/u/COROLLAGUY1)\ **Post date:** [May 16, 2019, 9:51am UTC](https://community.cartalk.com/t/exhaust-pressure-under-valve-cover/140434/2 "2019-05-16T09:51:37Z")
Check/replace the PCV valve. It may not be releasing the crankcase pressure into the intake manifold. Also,you may have a bad rubber grommet, not holding it tight enough. Here’s how to replace it [https://www.paulstravelpictures.com/Toyota-Corolla-PCV-Valve-Replacement-Guide/](https://www.paulstravelpictures.com/Toyota-Corolla-PCV-Valve-Replacement-Guide/)