Squeaking/Squealing out of dipstick?

[Yukonman1998]

I have a 98 Yukon. For the last few months i've had this horrendous squeak/squealing noise coming out of the engine bay. However, it only happens when the engine is warm, and only in an idle or when my foot isnt on the gas. I changed the water pump. idler pulley, belt tensioner, serpentine belt, and the PCV valve. NONE of these stopped the noise. Dumbfounded, I stood over my squeaky engine, and just started doing random crap. I get to the dipstick and pull it out slightly, the whistling STOPPED. I drove with the dipstick slightly out and the whistling only continued when I drive for longer distances. I have NO clue where to start or what it could be. Im newer to DIY vehicles and I'm really struggling to figure this one out. If you have any advice on what it could be, please comment below. Thank you!

 

[Fless]

Pull the dipstick out and determine if the tube is under vacuum (inhaling) or if it's exhaling pressured air.

 

[Yukonman1998]

Pull the dipstick out and determine if the tube is under vacuum (inhaling) or if it's exhaling pressured air.

Its exhaling the air.

 

[Fless]

Welcome to the forum. It sounds strange for sure but I am leaning toward a clogged pcv port or vacuum leak.

I'd have to go with what @OR VietVet posted in the other thread. Clogged PCV system or poor vacuum. Not sure what else causes crankcase pressure.

 

[Yukonman1998]

How does one clean a PCV system?

 

[Fless]

I assume that your '98 has a PCV valve. Start by cleaning or replacing it.

You may want to put a vacuum gauge on the manifold to see if it's within spec (recommended before and after the above for comparison purposes).

 

[Yukonman1998]

I assume that your '98 has a PCV valve. Start by cleaning or replacing it.

You may want to put a vacuum gauge on the manifold to see if it's within spec (recommended before and after the above for comparison purposes).

Ill give all that a shot and update you! Thank you for the help. I really appreciate it.

 

[OR VietVet]

He said he replaced pcv but you may have to pull intake to really clean the whole system and have to check oil drain back ports on heads while apart.

 

[gooffeyguy]

I'd have to go with what @OR VietVet posted in the other thread. Clogged PCV system or poor vacuum. Not sure what else causes crankcase pressure.

Bad rings allowing too much blowby will cause excessive crankcase pressure

 

[Eman85]

Push the dipstick in and pull the breather hose out of the left valve cover, the tube that goes to the air intake tube. Put your hand over the hole and see if you have vacum or pressure. If you have pressure go to the other valve cover and remove the PCV valve and see if it is pulling vacum.