hi i have a I6 in my comet, and recently i was driving and it started making a hissing noise when i stepped on the gas, it sounds like it's coming from the exhaust. it gets alot louder when i put a load on the engine. so whats wrong with my car?
First off...Welcome aboard! :Handshake Next, it really sounds like you have a vacuum leak. Hopefully you can pinpoint the hissing noise while listening under the hood while it's running. Inspect all of the small vacuum hoses close to the carb. If it's not them, it could be the carb itself. The screws in the carb could actually work loose and create a vacuum leak. You might be able to grab the carb with the engine running and see if it may seem loose by twisting or trying to turn it slightly. I have seen this on 6 cyl cars before. If that turns out to be the problem, you will have to take the carb off and tighten the screws from the bottom side. Good luck and let us know what you find!
If you do not notice any difference in the way the car idles (as would be the case with a vacuum leak), it is likely either a pinhole in the exhaust pipe, leaking around the exhaust doughnut, or leaking exhaust manifold gasket. edit: Ray is took quick! I am leaning towards vacuum leak also, because exhaust leaks generally have more of a pinging sound.
all i have for exhaust is a 3 ft pipe right now (and it has had leaks for a long time) , and i just had the carb off and tightened those screws you were talking about.
Were you trying to fix this problem when you tightened those screws? Did you check out the gasket under the carb at that time?
no i wasn't trying to fix the problem then. i replaced the gasket 2 months ago. i'm pretty sure the noise is coming out of the exhaust.
it's kind of a low toned noise, like a lot of air flowing through a large hole, it's a constant flow (no pulses).
Stupid question, but did you recently bottom out the car crushing the exhaust at all? It sounds like a restriction to me.
Not to steer away from exhaust problems, but I remember a very similar noise when one of my tires was balding (like myself) and probably not balanced. When I sped up the sound got louder but then again the car shook a little too. I guess I'm just making sure it's not a tire or drive train thing. Dinged drive shaft?
Does your car still have a catalytic convertor?? some times they will hiss through the exhaust before they finally plug up to the point that the car wont get out of its own way.Is your car slower than it should be?? this could also be a sign that its time for a convertor,(or a test pipe).Good luck.
I checked the exhaust no new holes, no bends I also remember a smell when this first happened, it didn't smell like engine oil (cause i know what that smells like) it might have been transmission oil. could it be the torque converter? my exhaust ends close to that area.
Good suggestion Mavman...that would explain the smell also. I never even thought of a cat on these cars. Mine's a 72, so it never had one.
