Vacuum noise

[71GTX440]

Need a little help on figuring out a good solution to the sucking/vacuum noise I have.

When I run my engine (440 RB), I get a sucking/vacuum noise from the oil dipstick tube. I have a new PCV valve on the D/S valve cover, going to the rear of my carb (QFT Slayer 650 CFM) and an additional air filter on the opposite valve cover as my PCV valve. Pulling vacuum for my distributor from the vacuum port on the side of my carb and pulling vacuum for my brakes from the manifold.

I shut the engine off and I get the whistling/vacuum noise, pull the dipstick, noise stops after a few seconds.

I checked all bolts, hoses, and other possible loose items and found none were loose.

Some assistance would be greatly appreciated.

 

[PurpleBeeper]

When you shut the engine off you say? First, I would try to definitely find the source of the "whistle". Can you put a vacuum gage on the dipstick tube with a piece of hose, start the engine momentarily & verify that there is vacuum (not pressure) in the dipstick tube? In my mind, the dipstick tube should be pressurized, if anything.

You might also want to check around for a possible vacuum leak. I've got a "whistle" right now that I can hear when I first hit the gas and I'm thinking I've got a crack in a vacuum line somewhere or my air grabber canister. Maybe you've got a small hose leak too?

Maybe find someone with some really good ears or use a mechanic's stethascope?

 

[rrTor-Red]

What's the condition of the PCV grommet? Have you checked it?

 

[RJRENTON]

Where are you letting the fresh air INTO the engine. If the Pcv is on the D/S valve cover, then the air breather should be on the opposite side valve cover. If the only opening is the dip stick tube, vacuum will pull air in that opening.
This is just my opinion.
Bob Renton

 

[71GTX440]

When you shut the engine off you say? First, I would try to definitely find the source of the "whistle". Can you put a vacuum gage on the dipstick tube with a piece of hose, start the engine momentarily & verify that there is vacuum (not pressure) in the dipstick tube? In my mind, the dipstick tube should be pressurized, if anything.

You might also want to check around for a possible vacuum leak. I've got a "whistle" right now that I can hear when I first hit the gas and I'm thinking I've got a crack in a vacuum line somewhere or my air grabber canister. Maybe you've got a small hose leak too?

Maybe find someone with some really good ears or use a mechanic's stethascope?

It is a vacuum, not a pressure at the dipstick tube. Dip stick is hard to pull out, but when I do get it out, the whistling noise stops.

I had a similar whistling problem on a different B body and I found a few loose bolts on the manifold. Took them out, loc-tite on the threads and re-torqued, whistling stopped

 

[71GTX440]

What's the condition of the PCV grommet? Have you checked it?

I bought a set of M/T valve covers and media blasted them. Installed new grommets (1 for PCV valve and 1 for the valve cover air intake) and new valve cover gaskets

 

[71GTX440]

Where are you letting the fresh air INTO the engine. If the Pcv is on the D/S valve cover, then the air breather should be on the opposite side valve cover. If the only opening is the dip stick tube, vacuum will pull air in that opening.
This is just my opinion.
Bob Renton

I have the PCV valve on the D/S valve cover and the air breather on the P/S valve cover.

 

[idrivemopar]

Is your breather clean? I have seen some caked with oil and sludge and or dirt, easy check, remove it and see if the vacuum/whistling on the dip stick stops!

 

[71GTX440]

Is your breather clean? I have seen some caked with oil and sludge and or dirt, easy check, remove it and see if the vacuum/whistling on the dip stick stops!

I can check the breather, but it is approx 8 months old with 5 months of that sitting in my garage over the winter. Thanks, never thought it would be the breather