well i posted this question before about this whistling sound from the engine but i have new info on it now. The guy told my dad before that the sound was a broken vaccum hose somewhere that he cant find. It only does it when u are off the gas and stops when u start pushin on the gas. Its extremly loud when u open the hood. Seems to be comin from the carb area. any clues?

 

Take carb cleaner and lightly spray the vacuum hoses and listen for idle change. That should help you find your leak.

 

Does it run smooth? What year is it?

 

yes it runs great. some times when u start it up and give it some gas it will want to die but after it warms up it runs alright. I think i might have found what it is. theres a metal line from the auto choke that goes down inbetween the manifolds and somewhere on the block. Its broken off so i dont know where it runs too. i noticed it last night. my other 300 had the same line and it was broken also but i forget where it ran too. i know i only found it when i pulled it out of the truck. some where on the lower part near the oil pan. but it didn't make anynoises. Theres also and red.orangish color rubber tube that comes out right under the top of the carb. any clue what these 2 lines are for?? ill take pics tonight

 

Hello, I have a 1994 Bronco 5.8 (351 F.I.) that seems to have that same whistle (sometimes) at idle and accelerating up to 30 mph or so. It doesen't do it after the engine warms up, just cold starts. It is quite a loud whistle and seems to be everywhere when the hood is up. Hope we can get some more good suggestions. Bill.

 

The problem is most likely a dirty throttle body. Where the butterfly opens and closes it gets crap built up there it needs to be clean. Take your air filter out and see if it gets louder. Bet it does.
rshissler Still need to know what year. If your is FI it is probably the same problem. If it has a vacuum leak at close throttle it should have a rough or fast idle.
The hose you are talking about for the choke sounds like the tube the heats up and tells the choke to open and close. Never mind about the year I was thinking that it was FI but if your talking about a choke then it carb sorry.
however you may still have the problem with your butterfly getting stuck a little. When this happens it disrupts the air flow and you get a whistling sound. Also check your carb gasket.

 

Thanks Chris for your input, I will check out the throttle body. It has a K&N filter on it. Bill.

 

at the time i opened the hood i didn't have an air cleaner on it and its was extremly loud. and it does kinda have a rough idle. i mean like when u start it up and let it set maybe 2 mins after u start it, it will stall, but if u start it up again and give it some RMPs it will idle ok. after that it will have that rough idle feelin like its not smooth but will jerk like its stallin alittle but wont. it will also stall if u give it to much gas at one time, like smash it to the floor while its idling. heres a pic of the lines im talkin about. http://photobucket.com/albums/v643/r...t=IMAG0005.jpg the one that is greasy and orange at the end and the metal line with fiberglass mesh around it.

 

When I done my k&n filter it got louder but I like it.

 

guess no one knows what they are. ill post it in the 300 section

 

It could be a small leak on one the hoses that goes to the smog pump. If it had a small pinhole in the hose, the the air, which is under some pressure because of the pump
would be forced out of the little hole and make whistling sound.