My truck can whistle
 

Does anybody know what would cause my truck to whistle when I turn it off. It also does it when I start it up most of the time. It sounds like its coming from the passenger side of the engine near the windshield. Sorry for the vauge description but I don't know anything about engines and I don't have haynes manual, my nearest autozone didnt have one for my year and havn't gone to another yet.

RE: My truck can whistle
 

Is it your HVAC system leaking the residual vacuum out? The blend door and defrost/dash/floor selections are all vacuum controlled.

RE: My truck can whistle
 

i would guess an air leak on the intake somewhere, its the only thing i can think of that is in that area and make a whistling sound without making other symptoms. if it were a vacuum leak you probably would have a trouble code or other symptoms. first go buy the repair manual, then check the air intake for cracks and leaks. i bet someone changed the air filter and didnt put the intake back together correctly

RE: My truck can whistle
 

thanks for the replies.
Its possible that the air filter got changed about a month or so ago we had work done on the truck because the speedometer was not working correctly(it wouldnt move until roughly 70mph), actually I think it was probably the speed sensor or what ever, but in addition to that the mechanic had to replace somthing else, im not sure what its called but it did somthing with the idle speed and was causing the truck to stall when coming to stops (that was annoying specially since it made steering very difficult) anyways, I am not sure if the mechanic replaced the air filter or not, my dad might know, but when i talked to him he after we got the truck back he didnt seem to know much of what they did with the truck. I'll keep yall posted as I figure things out, its hard when i dont have time. Do you think it could cause serious damage if this doesnt get fixed real soon.

Like i said i dont know much about engines but is the intake supposed to build pressure at some point cuz, i think what ever is making the noise had to have some sort of pressure and so when I turn the key so the truck is off the pressure is released and vice versa when starting up or within a few minutes of starting up. Anyways thats just my thinking

RE: My truck can whistle
 

not pressure, vacuum. the motor acts like a giant vacuum, air is sucked into the top of the motor and combusted then goes outt he exhaust. when you stop the motor the pistons rotate a few more times and continue to suck air, but only for a second. pop your hood and check the big plastic tube thing on the passenger side, there are some giant hose clamps holding it together. just give it a good visual inspection and check for leaks. when in doubt find someone that knows what they are doing, this is a very simple job

RE: My truck can whistle
 

Whats the best way to check your leaks? I think my grandpa used to pour water on the tubes and checked for bubbles, is that way it is normally done? Is there somthing I should be careful of doing this. Also what is the silver thing circled in the picture, the metal tubes on top are cold and have condensation on them, it's probably normal but it sounds like that is the area the whistling is coming from when I turn the engine off. My guess is that that things has to do with the A/C since its cold, but ill let you guys tell me what it is. Imma go back out and look around somemore

EDIT: I found one of those big round clamps really loose the one that goes from the back of square plasitc thing towards the cab but that didnt change anything with the whistling when starting up and turning off, but it did make the engine sound a little better, it sounded like it had more power, maybe it was just me cuz I was excited it might have fixed the problem, but it didn't.

RE: My truck can whistle
 

yea that tube that you fixed the clamp on is part of the intake. the silver thing in the picture is part of your air conditioner. dont spray water out of a hose, you can fill a spray bottle with just a drop of soap and the rest water. spray it in the area that you think is making the sound, you should be able to see most leaks. you can also double check the long rectangle box thats attached to the tube you adjusted, its also part of the intake and could whistle if it were loose

RE: My truck can whistle
 

Yea I checked the clamp for that both on the inside of the box and out side, actually the rectangle box doesnt have top on mine like it did in the picture but they were all tight. If it were a leak in the intake wouldn't it whistle at all times not just after starting the truck and after shutting it off. While running I do not hear it

Thanks again for your help, I am sure we will get it figured out but not tonight cuz im too tired

RE: My truck can whistle
 

yea it would whistle all the time but you might not notice it over the engine noise. try the soapy water trick

RE: My truck can whistle
 

I don't think it is whistling all the time because when I turn it off, everything is quiet at first then a few seconds later the whistling starts for 15-20 seconds and it starts loud and then gets quieter as it goes. And when starting up I don't hear it initially but a few seconds later it starts and then goes away after a few seconds. Not sure if it would help but I could probably get an audio clip of the whistling.

EDIT: I think it is somthing with the Air Conditioner because I tried it with the Air Conditioner turned off and there was no whistle. If you want to hear the whistle, I have put them here.

RE: My truck can whistle
 

thats a weird wistle. I've never heard that before. it sounds like some pressure is building up somewhere. so it doesnt do it at all with the a/c off eh. can you even tell where the whistle is comming from. I'm guessing the a/c is buildin up pressure somewhere and then when you shut it off it's escaping.
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RE: My truck can whistle
 

thats what i was thinking, it sounds like its coming from the silver cylinder that is circled in red a couple posts up, or somthing down beneath that thing, the cylider has somthing to do with the air conditioning because two metal tubes coming out the top are icy cold and kurbycar32 said it was...lol.

RE: My truck can whistle
 

all i can say is wow, thats freakin weird.
definitely not the intake. i think your right to suspect the A/C system, but if it is you wont be able to diagnose it yourself. i think because it whistles so long after the motor is off that its very unlikely that its a vacuum leak. after hearing the sound i would go back to horatio's suggestion about the vacuum actuated blend door, another thing that as a rookie i dont suggest you attempt to repair yourself. i think you should go buy the repair manual and look at the heating/AC section and find where that blend door is, stick your head near it, and make sure thats your problem. its very likely that you will need a mechanic to get this fixed, although i will commend you on providing excellent descriptions of your problem[sm=smiley20.gif]

RE: My truck can whistle
 

Yea I don't intend to do any repair myself unless its really easy. I picked up the haynes manual last night and I found out that silver cylinder is an accumulator...yay im learning parts...lol, anyways would you be able to explain to me what the blend door looks like, and/or what it is, I am clueless as to what to look for, both when looking at the engine or the manual, I didn't see anything that stuck out that said blend door, but I havn't looked extremely hard, I was looking more at the pictures...lol

Imma start googling about it now

RE: My truck can whistle
 

behind your dash is a big plastic vent system. at a point, air comes in thru one hole. cold air on one side and warm on the other. theres a vacuum actuated flap that "blends" the right amount of cold and warm air to make you comfortable based on where you place hot/cold dial on your dash. the theory is that when you shut down your motor and therefore stop producing engine vacuum, this flap is releasing the vacuum and making noise doing it. i think one way to test this would be to shut down the motor with the temperature dial in 3 spots: hot,cold and 50/50. im betting that at 50/50 you don't hear the noise because thats the natural position of the flap

RE: My truck can whistle
 

i was reading further up and noticed the soapy water test thing ,with vacumn this test will not work simply because it is sucking it in not pushing air out so there fore it will not create bubbles
my father used to use WD-40 to test for vacumn leaks spraying it around or on the line that was thought ot be leaking and if it was then it either reved up or down depending on whether or not is was at the carb inlets sucking it into the carb and mixing with the air being fed into the intake

but none the less it does work

RE: My truck can whistle
 

I just tried with temperature knob at cold, 50/50 and hot all with the same results, when you say "behind your dash" does that mean tearing apart my dash or like just behind the glove box, which i think the haynes manual showed how to do.

RE: My truck can whistle
 

Sounds like its your a/c ,some cars will make the noise some dont.I think its from the pressure dropping in the system.If the noise bothers you shut the a/c off before turning the truck off.I'v heard that if you shut the a/c off and give it time to cool down it will last longer.

RE: My truck can whistle
 

mine did that when istill had a clutch fan.......i took it off and since our trucks are equipped w/ an auxiliarry electric fan(comes on when engine is hot and or comes on when a/c and defrost is on)......took it out and walah....

RE: My truck can whistle
 

no but it spraying it on a vacuum leak makes it gurgle and you can watch the bubbles get sucked in :-)

RE: My truck can whistle
 

It seems like it only does it when it gets hot outside, because before it wouldnt do it in the mornings when it was cool out but later in the day it would and now that the days are getting cooler, I don't hear it as often. So now that will make it a little harder to diagnose now that I can't listen to it anymore. Also one day I was messing with the A/C control knob (the one with "Max A/C" etc) and I was slowly turning through each thing and when I got to the last few, I would get a whine that would go in addition to the whistle, except the whine wouldn't stop until I turned the knob, then it would stop and then go again, and after I got it to start whining it would do it on all the other positions except max a/c (I think, this was about a week and a half ago I cant remember and I havent been able to do it again).