Alright i really confused " shut the **** up " iv got an extremely loud sucking sound while going down the road, it wasnt doing it yesterday or earlier today. I went to get on the freeway to go a couple cities over to get some cement for our upcoming project and i excelerated " spell check " to get on the freeway and i got her up to about 3500 and let her shift into 5th once i got to about 75 and took my foot off the throttle and heard an EXTEMELY loud sucking sound. So i rolled down the window to have a smoke and it got louder and louder, i know i have a leak between my passenger side Y pipe and the manifold but it's never been this loud before and it sounds like it's coming from behind the dash. My temp is good and iv got heat so i know it's not the heatercore, no steam from the vents etc etc

It gets louder as the RPM's climb, only way i can explain it is that it sounds like im running with out an aircleaner but x 100

I have a slight loss of power and im waiting for the engine to cool down to see if maybe i blew a headgasket but also the truck isnt smoking at all. it was running fine not even an hour ago.


any ideas guys ? i dont have funds to toss into this thing to play the blame game replacing part after part.

 

Sounds like a bad vacuum leak. Check the pvc valve for a crack. I broke mine yesterday and had to drive to the parts store and there was a really loud sucking sound. It could be a vacuum line under the dash for the HVAC system or one under the hood.

When you let off the thottle after accel the throttle blades close leaving no air for the cylinders causing very high vacuum. Hence the loud sucking sound.

 

But if it was a vacume leak it would idle weird, it idles just fine it just sounds like something is sucking like crazy

 

Not having a gasket between the aircleaner and throttle body cause any serious sucking sounds ? it wouldnt think it would sound any different then having a open throttle body

 

Even with my pcv valve broken and the huge vacuum leak it left I had no problems idling at all. The IAC just adjusted. I didn't have a noticeable power loss either.

The missing gasket may cause a sucking sound but if it has been gone for awhile why would it be an issue now?

 

I guess it wouldn then, the main reason why i didn mention the PCV is because it's bran new not even 2 weeks old along with my breather filter. Man i really dont wanna have to go through every one of these damn pos plastic vacume hoses

 

I don't know if this will apply to you but two years ago the truck had a strange sucking sound from under the dash/ firewall area, It turned out to be the brake booster, the rubber diaphragm had a hole in it not big enough to effect brakes or the idle but very loud. Just a thought and easy to test. Just remember that if you drive it with the vacuum hose off and plugged you will have NO power brakes.

 

I took it down the road earlier, now you can barely hear it from inside the cab but it's loud as hell on the outside,REALLY loud if you're going up against a guard rail on the freeway. But i still have a slight loss of throttle response. No blown headgasket from what i saw, i was a qt low on oil "blown plenum" but no oil in the water and no water in the oil so that's good so far, tomorrow im going to go buy new bolts for my joint at the Y pipe and manifold an tighten those up to elminate that problem so i can get a better feel for the effected area.

Does any one know of any part store that sells the steel ring that goes between the manifold and Y pipe ? mine is broken and autozone doesnt have them neither does oriles.

Also i checked the brake booster it seems fine, i dont hear any hissing coming from that side of the truck

 

I had a pretty bad sucking sound a few months ago, turned out to be the cluster F*** of plastic lines on the passenger side was in about 5 pieces, i changed over to rubber lines everywere i could and it solved it

 

well i was doing some digging on the engine and i think i might have found the problem, apparently one of my manifold bolts either rattled loose "HOPEFULLY!" or snapped off because it's backed out about a 1/4 inch and it's too hot right not to try an tighten it cause i already burnt the **** outta my self tryin to get to it.

I'll take pictures when i goto mess with it