Frog in my ZX2

I have a 99 ZX2 that when running at idle soulds like I have a pool of frogs under the hood. Every now and then a squeel like a belt squeal would sound
and then go away. I replaced the belt but the noises still exist. For some reason I was frustrated and trying to find this mystery noise and I removed the oil filler cap and lots of air pressure exited and the noise went away. As soon as I put the filler cap back on the noise returned. I thought I was imagining it so I repeated the procedure with the same results. Now I am wondering if anyone has experienced this and could maybe point me in the direction of what's needed to repair or what could be wrong. I am thinking there is some sort of valve regulator gone bad, like an EGR type valve but not sure.
Any help to this backyard mechanic is appreciated.
Thanks
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sf, I have had the same thing happen to me!! I have a 98 ZX2 and it sounds like a ghost cry or something. I have no help to give you as I replaced my timing belt and all other belts are fine but it still happens. I appreciate your input and will try the oil cap as well. It makes sence as it only happens after warming the engine up for a while.
Thanks, Andria
sf wrote:

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I would replace the PCV (Positive Crankcase Ventilation) valve and be sure the hose coming from it is not plugged. The valves are a maintenance item, they have them next to oil filters in parts places. They are designed to draw air thru the crankcase to suck any vapors into the engine where they can be burned. At one time, the vent to let air in was in the oil filler cap. It is usually a fitting connected from the valve cover to the air intake somewhere these days.
Good Luck
Paul in Dayton

frogs
removed
away.
was
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