Loud rapid rattle from PCV, while running.

[TCONNELLY]

I'm getting a loud rattle at idle and even louder during part throttle. I replaced the PCV and am still getting the noise. The new one looks different from the one that was there. It's so loud I can here it from the cab, while driving. The parts store looked it up and ordered it, so it's supposedly the correct part.

Has anyone experienced this? Is it an indication that I have the wrong part?
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[geezer#99]

Are you sure it's the pcv?
Pull the hose off the carb and plug it to test.
What do you have for air inlet on the other valve cover?

[TCONNELLY]

Originally Posted by geezer#99

Are you sure it's the pcv?
Pull the hose off the carb and plug it to test.
What do you have for air inlet on the other valve cover?

I'm sure it's the PCV. Pluged it and it stops. The air inlet on the other valve cover is the stock set up, connected to a collar between the carb and air cleaner. It sounds like it's a large volume of air passing through causing a violent rattling of the check ball.
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[geezer#99]

Do you have a good solid vac hose. When they get older they collapse easily.

[TCONNELLY]

Originally Posted by geezer#99

Do you have a good solid vac hose. When they get older they collapse easily.

The thought had crossed my mind that perhaps it could be the hose causing it. Collapsing rapidly causing a pulse in the vacuum. I'll try changing out the vacuum line.
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[storm9c1]

Next step after that is to pull the pcv valve again and stick your finger over the valve cover hole. If you can feel pulsing pressure, you may have a cylinder that lost a ring and causing lots of blowby. Let's hope not.

Compression and leakdown test would be next if you suspect that.

[homemade87]

Do you have a aftermarket cam in the engine . An aftermarket cam can cause low vacuum in the intake and pulse the pcv ( seen this many times ) . If it is a stock cam you most likely have a burned intake valve allowing the cylinder pressure to push back into the intake and pulse the pcv . You can hook up a air hose the spark plug hose to see if one of the cylinders is pushing air into the intake .

[TCONNELLY]

Originally Posted by homemade87

Do you have a aftermarket cam in the engine . An aftermarket cam can cause low vacuum in the intake and pulse the pcv ( seen this many times ) . If it is a stock cam you most likely have a burned intake valve allowing the cylinder pressure to push back into the intake and pulse the pcv . You can hook up a air hose the spark plug hose to see if one of the cylinders is pushing air into the intake .

I'm pretty sure it's a stock cam. I'm getting a bit over 20 inches vacuum at idle. When I pull the valve out of the grommet ,at idle, I feel a lot of vacuum pull through the valve. Is this normal? Shouldn't it close at idle and open up at higher rpm's?
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[homemade87]

The pcv will pull at idle . The spring valve reduces the volume when it closes at idle and low rpm, other wise it would be a big vacuum leak . 20in of vacuum is pretty strong . Just by putting your finger over the end will feel like a lot . That normal .

With a stock cam at this point I would suspect a burned valve or sticking valve pulsing back into the intake and allowing the pcv valve to pulse when the cylinder pressure enters the intake .

Note , The pcv valve never closes it only restricts