whistling from valve cover breather

[jd21]

I cant figure out why my valve cover breather port is whistling when rpms are dropping right around 1000rpms. its a short high pitch whistle right before the rpms settle to idle. Im have a problem with idle surge and cant find any boost leaks.

 

[jd21]

Anyone?

 

[ervin00]

Sounds like you have blow by. Do a compression test and cylinder leak down test and post back with results.

 

[jd21]

No blow by, compression is 160 across all 4 on a warm engine. No oil in any intercooler pipes or intake track and ive never had a problem with the dipstick poping or anything like that

 

[lil corb]

Are you certain it isn't the bov leaking at idle? Read a thread about that somewhere on here where there was whistling from leaky bov.

 

[jd21]

Ive tried two different bov and still the same. If I take the hose off the breather port the whistle gets a little bit louder so thats the only thing I think it could be

 

[90gsxjuice]

Check your pcv

 

[bryanwheat]

Sounds pretty normal being that there is more vacuum pulling air thru the engine at idle and decel. Do you have one of those cheap filters just stuck on the nipple?

 

[jd21]

Pcv is new oem. I do not have a filter on the port just a vacuum line ran to the intake pipe

 

[bryanwheat]

Pcv is new oem. I do not have a filter on the port just a vacuum line ran to the intake pipe

Is it only making the noise with the hose unhooked? I don't see how you would even hear the noise if the hose was in place.

 

[Zufelt]

This might sound strange but are you sure it's not coming from the MAF area? I had a problem with whistling when it was at a set RPM. It was right by the MAF. I thought it to be the little rubber piece that's in there had a little piece missing.

 

[jd21]

No its making it with the house hooked up to, I have no idea what it could be its definitely coming from the valve cover breather though

 

[c2ypt1c]

Same thing happened to me once I installed my greddy bov. The small lower port sucks in air under vacuum causing it to whistle, at just the right rpm. You sure it's not your blow-off valve? What kind do you have?

EDIT: Heh, just had an idea. I'll put a vacuum cap on it and see if it goes away. Being that I'm on SD, it never bothered me but I'll let you know if that's definitely it.

 

[jd21]

1g bov uncrushed

 

[r6speed]

Was the culprit of your whistle ever discovered? I've had the same problem for years.

 

[miliman13]

Same only on idle