PCV - Vacuum problem

[72K10]

I've got a squealing sound from the front of my engine. When I pull the pcv from the valve cover, I get a big sucking sound and the squealing stops. The ball rattles in the valve, but I'm wondering why vacuum builds up so much that it makes the engine squeal. Anyone else had this problem?

Chris

[4x4Poet]

Usually, an engine-running squeal means you have a vacuum leak. Check your caps, then maybe the hoses, then maybe the carb mounting gasket. If you have a propane torch, you can shoot unlit propane around the carb and intake vacuum connections. If you find a spot where the idle increases, you've found a vacuum leak. Best to do this with a wand, though.

[dmec]

a friend of mine just had the same problem. found he didnt have a breather on the opposite valve cover, which didnt allow air into the engine crankcase, causing pressure to build and create a whistling sound at the crank seals.

[72K10]

sounds just like what I have. It's definitely not a vacuum leak, since it's creating a lot of vacuum (sucking) pressure that is released when I pull out the oil filler plug or the pcv. But I didn't think these trucks had crankcase breathers originally? I'll have to check out some pics of original engines. Thanks, Chris

[PMS]

On the passenger side of the engine on my 72 GMC it has a hose / tube that leads to the air cleaner spacer that it can draw air through.