Hum/moan at idle fixed, '00 XLT SOHC...

[fgump]

Over the last month or two, my '00 XLT SOHC (77k miles) had developed an annoying hum/moan at idle, that had all the symptoms of a dirty idle air control valve (but the idle was just fine, steady as a rock). I had replaced the IAC valve two years ago for stalls at idle. Turns out that the PCV valve (that I replaced in 2000 at 32k miles...I bought my '00 used in '00) had failed. It didn't fail stuck; the seam came loose that holds the top and bottom together, allowing the valve to suck in air past the flange. The hum was air rushing into the PCV. Picked up a new one at Advance for $2.61, and the problem is gone.

Cheap, easy fix (only took about 5 minutes of grunting in the Advance parking lot to get the T-connector off the top of the !@#% valve, 5 to get it back on, and 1 minute to reconnect all the hoses).

Hope this helps someone chasing a noisy idle.

 

[MazdaGreg]

I had that same problem! I can't believe somebody else had that issue. I couldnt figure out the stupid thing until i just pulled it out one day, and it was vibrating so bad, because once again, the seam came apart, and it was only 6 months old or so. Sounds like we bought the thing at the same store out of the same bin! Idle's a lot lower also, doesnt it? mine went from 1200 right back to 700 where it belongs!

 

[Hectanooga]

Where is the IAC? I think I might have that same problem.

 

[MazdaGreg]

It's not the IAC. it's the PCV. Positive Crankcase Ventilation Valve. It's on the Driver side Valve Cover on the First Gen 4.0. Not sure where it's at on a '98