Hey guys, I have started to notice this in the last few days. When I shut the truck off it sounds like its relieving pressure, I hope that makes sence. It kinda makes a verrrrrrrr then it gets higher pitched, and stops. It only does it for a few seconds after I shut the truck off.

What the heck is it? I am going up north again this coming weekend and I would like to fix it before I go.

~CB

 

Both of my 03 4.0's made a sucking sound coming from the intake(area) when I turned them off sometimes

 

Yeah, so what the heck is it? Its driving me nuts, and its kinda embarrassing....

 

Just a lil reverse flatulation I guess

 

Bob has some technical term for it and explains what it is. Its fine most of our trucks all do it. Depends on the outside temperature and pressure in the air

 

read this

https://www.ranger-forums.com/forum2...ad.php?t=29712

 

^^^^ Well that seems like what it is. I guess I wont worry about it?

 

I wouldnt, its nothing major and it will more then likely go away when the weather changes.

 

Ok.....

 

It most likely is what Bob describes. But... you may have a IAC valve that's dirty and not closing all the way. Even though it won't hurt anything.. it maybe dirty and this is why your now hearing it.

Rich

 

Nah, not the IAC. I just cleaned it and it was doing that before I cleaned it, as long as it doesn't hurt anything, I guess I wont worry about it.....

 

If it is manifold pressure that you are hearing, I doubt changes in the weather will have any effect. Atmospheric pressure doesn't change enough to do that.

 

Mine has only done it in the summer months...

Im not looking forward to hearing it when it gets warmer either...

 

its no big deal. stop going crazy

 

mine always does it, also my friends s10 ss and my other firends dodge ram and we all have Air intakes and they all do that mine is loud and the dodge is really loud. before we put them in they didnt do that.
so u should be fine

 

if you guys are talking about the same sound that i'm thinking, it's nothing more than the brake booster relieving pressure once the motor shuts down...the brake booster draws air from the intake system and once you shut the motor off there's no more air to be pumped into the brake system, so it relieves the leftover pressure...

 

interesting......

 

Mine does this also, just seems like it is louder in the colder weather. The past week or so it has not been noticeable. Like most of the other posters on here I was told it is no big deal since it is just relieving pressure.

 

I appoligize up front.. but technicaly it's not relieving pressure. The outside atmoshpere is rushing into the void/vacuum of something. (manifold, brake booster, ect..)

Ok.. I feel better now.

Rich

 

None needed. So what you're saying is that it is equalizing the pressure between the outside air and engine. That makes sense.

 

thank you! you are completely correct...and this should apply to both noises that the Ranger makes...one is under the hood and comes from the intake manifold and brake booster, the other is the HVAC system and is coming from the passenger side behind the dash....

 

I wonder why mine has only made the noise in the summer?

 

 

The brake boost operates on vacuum not pressure. It also has a valve in it to hold the vacuum when the engine is turned off. This is a safety feature that gives you full power assist braking, at least once, if the engine dies. There should be no sounds coming from the brake booster when the engine is turned of unless you step on the brakes.

 

Are you sure it's not a particular steeing of the HVAC controls? Might try shutting it off in different modes.

Rich