Squealing at idle, releasing pressure when it shuts down, wtf?

[281pony]

i found out earlier my problem of squealing and releasing pressure were related so im making another post.

we just installed my new heads, all new gaskets, ect. the problem is, when i start the car and it idles, it squeals like a belt. when it is shut off, it lets out a trumpet type sound. the longer the car has run, the longer the sound is released when its shut off.

i have tried to pinpoint is as much as i can think of. the sound is only a few seconds long so its hard to feel awhole lot between shutting off the engine, running under the hood, the heat, and looking around. when its running it is too hot to feel for any airleaks on anything specific. i tried with water checking for air bubbles but nothing.

any idea what would cause squealing running, and let out a trumpet pressure sound when just shut off? what can i check specifically?

 

[Schlodes]

Just a shot in the dark.

Your valve covers. Do you have the stock hose that went from the fill tube to the T body hooked up still? If not, do you have a breather on one of them at least? I ask because if the PCV is sucking air from the crankcase at the back of the intake, it has to draw that air in from somewhere, and if it can't... [I had the nipple on my stock valve covers oil fill cap plugged off cause my T body never had the provision to hook it up] ....once it builds enough vacuum in the crankcase, it will start to suck air through a seal.. mine was doing it from the front cover seal... just like you say.. sounded like a squealing belt or accessory, then shut it off and a funky sound. I discovered it one morning... engine is running, squealing away, I yanked that liittle rubber plug off the fill tube, and it made a huge "SSSSSSUUUUUUU" and the squeal noise was gone. Stuck my finger on the oil fill tube nipple and held it there,... squealing noise came back... let go.. SSSSSUUUU... so theres vacuum there for sure.

 

[Psydwaze]

I'll second that suggestion. I had plugged my breather tube that feeds to the intake stream because I was changing around my plumbing MAF setup. Exact same symptoms.

 

[281pony]

that sounds like a damn good suggestion.

so if i pull the little nipple on there and it goes away, should i leave it off? or put a breather back on?

i had one of the little K&N type breathers on my valve covers before we did my heads, then i took it off for a oil cap instead.

 

[281pony]

that fixed it. thanks alot for the idea.

if you lived closer i would have taken you for the joy ride i just had now that its all fixed

 

[HISSIN50]

depending upon how you redo the hosing, just try to make sure you are not introducing unmetered air into the intake....PCV flow is bi-directional.

good luck and nice catch Schlodes!

 

[281pony]

i dont have hose running from the neck to the intake.

just had nipples on each end. i got a little breather for the pcv and it fixed it

 

[HISSIN50]

is the TB nipple capped?

 

[281pony]

yep. they were both capped.

now the pcv has a breather, tb is still capped. works fine, just makes a quick, less then a second air releasing sound when i shut it off. not even really noticable. sounds alot less embarrasing/irrirating then a damn fifth grade marching band under the hood

 

[HISSIN50]

good deal - just making sure no unmetered air was getting in.
nice work and glad to hear it is good to go.