brucksch

81 stock engine. I kept hearing a rattling under the hood and finally traced it down to a fairly new (3 months) PVC valve. Is this normal that I can hear the rattle of the PVC over the engine noise?

7T1vette

Not really. There should be a [light] spring that keeps the little valve seated until enough pressure is built to cause it to release. That spring should prevent that valve from rattling (under normal circumstances). Perhaps that valve didn't get assembled properly. You might go to the auto parts store and see if another of that item responds the same.

RonR80

just get another one and make sure you don't have a vacuum leak on the hose

qwank

make sure you get an ACDelco brand valve

LannyL81

I do not think you should be able to hear the PVC valve. I did on my '81 and then found that one of the rocker studs had come out of the head.

This was with the original heads...which are very prone to cracking. I suggest pulling both valve covers and taking a real good look.

STINGRAY1WORD

Make sure its not the heat riser valve between the exhaust manifold and the exhaust pipe.

brucksch

$4.00 and the rattling is gone. I had used a stethoscope with a metal rod to pinpoint the noise to the PVC valve.
Also checked the vacuum line and it was pulling strong and consistent.

Thanks all.

brucksch

The heat riser is on the opposite side of the car. But I did check it and it's working well. But that does raise the question of what can I use to lubricate the heat riser valve? It sure is rusty and I was surprised it worked so well.

qwank

GM heat riser valve lube and penetrating oil. It also works great for loosening up frozen bolts, nuts hinges etc.