Arod_562

For some reason after a quick drive just to get gas i come back home and hear this hissing sound coming from around the passenger side Valve cover area.

https://youtube.com/shorts/bJSI7Gt2uEE?feature=share

^ Heres a video showing the noise im talking about but cant pinpoint exactly from where its coming from. Anyone have any ideas as to where it could be from or have had this hissing noise before. Car runs perfect other than that, No weird idling or surging and dont have any codes for a Lean condition like from a vacuum leak. Does sound like a vacuum leak but isnt affecting my idle or how the car runs.

Arod_562

^ had to upload video here since link wasnt working above

icer5160

iTrader: (4)

Is the noise still present after shutting off the engine or only while the engine is running?
-Icer

Arod_562

sorry for late reply but only present while the car is running, i know its a Vacuum leak but cant find where its at lol. Im picking up a Smoke machine soon and feed it through the brake booster and hopefully it shows me where the leak is coming from so ill update this soon 🙏🏽 But as of now my idle is Steady and doesn’t fluctuate plus the far runs strong still so its a very small vacuum leak that isnt affecting my idle yet luckily

AznKaos15

iTrader: (1)

​​​​​​​Bump to see if a fix was found.
​​
Hearing the same thing coming from the same area. Also HR

Arod_562

sorry on late reply but ive come to the conclusion that i think the noise is just normal lol, i did a vacuum leak test with the smoke machine and no leaks at all from anywhere in the intake or pcv system. Ive also checked in my friends Hr and his seems to make that hissing noise as well but hust a little quiter than on mine.

AznKaos15

iTrader: (1)

Better late than never.
I notice the hiss sound after it hasn't been driven for a while and during initial warm up.
It goes away after going for a drive or If I drive it the next day, no hiss.
If it's a daily driver, it might not even hiss.

Aeneas137

well, the smoke test won't work when the problem is the intake manifold. because that would be sucking air in through a leak. you might want to check the seals around the TB, and check the air pipe seals. it's very easy for a small leak to get in through that pipe from the filter to the TB and it would definitely make a hissing sound. That's an easier check first. If that doesn't come up with anything, then pull the intake manifold off and reseal it.

Arod_562

i did the smoke test through the brake booster hose that attaches to the manifold so smoke is going through the entire intake system and manifold. And i still had no leaks but i have the same hissing sound still to this day but car runs strong still

Aeneas137

I don't think you understood what I said. smoke will not come out of a manifold leak because vacuum is sucking into it, not out of it. a smoke test will not work if you have a bad intake manifold seal. it also won't show you a TB or air tube leak because it is drawing in, not pushing out.

Arod_562

no i get what you mean but ive done this same test on other Hr and Vhr motors and its helped me find leaks from loose intake clamps, bad tb seal and from the manfiold itself. Its even helped me find a crack in my friends 370z upper manifold. So if its worked for all there cars im pretty sure it would work for me and i have no smoke coming from anywhere indicating a leak. But as i said above all of my friends Hr make a slight hissing noise at idle mines just sounds a tiny bit louder than theres lol

icer5160

iTrader: (4)

You don't run smoke tests with the engine running. So there shouldn't be any manifold vacuum present. If done correctly, meaning the air intake tube is blocked off at the filter box or in this case just before the MAF tube. Assuming there's a compromised seal, then the smoke should begin to leak out of the problem area after a few min of pumping it into the intake manifold (various ports to choose from).

Cheers!
-Icer