Hissing sound from engine
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Junior Member
Joined: Mar 2018
Posts: 22
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2012 C300
Hissing sound from engine
Hi guys I need a little help here, I changed my engine and cabin air filters today, everything works fine with cabin filter. But the screws of the air filter box was kinda worned out and I tried my best to make it tight enough. After I put the air cleaner and start the engine, I can hear a hissing sound around right side of the engine intake hose, sounds like the air is leaking.
I can't feel the air with my finger, and I'm pretty sure I reconnected everything from changing the air filter. The problem is I don't know where the hissing sounds are coming from, so I just want to ask where of the right side of the engine can leak air? I assume maybe it's a vacuum leak but I didn't even touch anything else in the engine bay, and the second reason might be the airfilter box are making the sound cause it's not sealed up?
I drove it for like 10 miles and everything was normal, no lose power, no rough idle and normal mpg.
Please help, thank you!
I can't feel the air with my finger, and I'm pretty sure I reconnected everything from changing the air filter. The problem is I don't know where the hissing sounds are coming from, so I just want to ask where of the right side of the engine can leak air? I assume maybe it's a vacuum leak but I didn't even touch anything else in the engine bay, and the second reason might be the airfilter box are making the sound cause it's not sealed up?
I drove it for like 10 miles and everything was normal, no lose power, no rough idle and normal mpg.
Please help, thank you!
Member
Joined: Jun 2015
Posts: 231
Likes: 31
2011 C300 4Matic Sport
Have you tried to reseat the air filter box. I suspect you did not reinstall it correctly.
Was the hiss gone after 20 secs? My car also has that sound from a cold engine only, it goes away and then RPM drops to 600 ... to let me know that engine is warmed up
Was the hiss gone after 20 secs? My car also has that sound from a cold engine only, it goes away and then RPM drops to 600 ... to let me know that engine is warmed up
Super Member
Joined: Nov 2008
Posts: 604
Likes: 29
From: SA
2008 C350-Sport-AMG-Active Agility Pack(Not reliable) +Izuzu KB6 3L(It seems Reliable)+Mazda
I listened to video, and it it seems you on to something, the sound stops if you press any side of that joint on the rubber pypes, I think you find your answer around there.....Ok not your video, "sounds like this".
My experience is if the airbox is loose on its intake mount over MAF sensor, you get engine light, which goes away if you fix it.
This sounds like intake manifold vacuum, connections from below throttle body it must be to have this vacuum leak, so stuff that uses vacuum to operate I would search for and their connections to find the vacuum leak.
My experience is if the airbox is loose on its intake mount over MAF sensor, you get engine light, which goes away if you fix it.
This sounds like intake manifold vacuum, connections from below throttle body it must be to have this vacuum leak, so stuff that uses vacuum to operate I would search for and their connections to find the vacuum leak.
Last edited by Moto_Guzzi; Oct 17, 2018 at 03:16 PM.
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