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PCV valve driving me nuts!
https://slantsix.org/forum/viewtopic.php?t=24694		 Page 1 of 1
Author:  Jopapa [ Wed Aug 29, 2007 4:24 pm ]
Post subject:  PCV valve driving me nuts!
Well now that the car's running again and I'm back in the game for tuning it up, I'm trying to find out why the frak my PCV valves rattles CONSTANTLY when the engine is running. It'll sporadically quiet down for a few seconds and then just rattle away again. I've replaced it twice and the new ones rattle just as much. I had thought the old one just got gunked up or something and that caused the rattle, but even clean new ones are rattling. It's incredibly annoying since this is the only "abnormal" sound my engine makes now and I want to get it fixed!

Any suggestions?

Edit: If it makes any difference, my valve cover is an OEM cover, with the baffles. Not a cheap Chinese chrome one.
Author:  SlantSixDan [ Wed Aug 29, 2007 4:31 pm ]
Post subject: 
What brand and part number valve are you using?
Author:  polara pat [ Wed Aug 29, 2007 4:35 pm ]
Post subject: 
Is it possible that your rubber grommet has hardened from heat and oil and isn't making a proper seal? I had some similar issues and this cured my rattle. The pcv is after all just a ball bearing in a plastic (or metal) seat trying to make a one way air valve. So it's pretty primitive.
Author:  Jopapa [ Wed Aug 29, 2007 4:43 pm ]
Post subject: 
Quote:
What brand and part number valve are you using?
I've used the standard Napa/Echlin 29207 and just installed a BWD PCV207 with no change at all.

One of the guys I talked to suggested excessive blowby, but if that were the case, I would expect the valve would be all gunked up and stuff.

Pat, it's got a brand new PCV grommet and breather grommet as well, along with a brand new breather filter.
Author:  ceej [ Wed Aug 29, 2007 6:40 pm ]
Post subject: 
Mine started doing that with a new sweep air filter as well. When the intake is at high vacuum, (Idle or low speeds with minimal loading,) more sweep air is drawn through the engine.

Perhaps some insulation of some sort over the PCV will help.

CJ
Author:  SlantSixDan [ Wed Aug 29, 2007 6:59 pm ]
Post subject: 
OK, NAPA's changing PCV suppliers so often any more I can scarcely keep track...did they give you the plastic-body or the metal-body design? I don't know which design the BWD unit is, either.

You may be able to suppress the rattle by adjusting the engine idle speed slightly this way or that. If it's at 750 rpm (hot, in Neutral) try 825 or 675 instead.
Author:  mrhite65 [ Wed Aug 29, 2007 9:21 pm ]
Post subject: 
Quote:
Mine started doing that with a new sweep air filter as well. When the intake is at high vacuum, (Idle or low speeds with minimal loading,) more sweep air is drawn through the engine.

Perhaps some insulation of some sort over the PCV will help.

CJ
Could you elaborate more on this? What is a sweep air filter? And what are you suggesting with insulation? Mine happens after warmed up in drive at idle and low speeds. I've had this problem for a while now. I was told on this site that it was a vacuum leak from the intake or carb, which I cannot find.
Author:  ceej [ Wed Aug 29, 2007 11:12 pm ]
Post subject: 
I've got three holes in my valve cover. One for the crank breather, which is connected to what I'm calling a "Sweep Air Filter," one for the PCV Valve, and another for the filler cap.

The crank breather normally hooks up to the air cleaner, and allows clean air to be pulled in one end of the valve cover, ultimately to be drawn out at the PCV valve. Engine vacuum draws air through the PCV, which sweeps the fumes from the engine. This also prevents the build up of pressure in the crankcase

My particular setup uses a separate filter, not drawing from the air filter itself. Not because it's any better, but due to extreme clearance limitations, and not wanting to have to deal with a big chunk of hose every time I remove the Air Cleaner base.

Image


I'm not going to bother with it, but if the noise is too annoying, just make an insulating cover, capable of withstanding the heat, and Zip-Tie it to the PCV to knock down the noise.
It's a vacuum leak of sorts. A built in one.

Clear as mud? :lol: It's late. I could be all jacked up. Where's my pillow?

CJ
Author:  Jopapa [ Wed Aug 29, 2007 11:17 pm ]
Post subject: 
Quote:
OK, NAPA's changing PCV suppliers so often any more I can scarcely keep track...did they give you the plastic-body or the metal-body design? I don't know which design the BWD unit is, either.

You may be able to suppress the rattle by adjusting the engine idle speed slightly this way or that. If it's at 750 rpm (hot, in Neutral) try 825 or 675 instead.
It's a plastic body unit. Kind of a sickly yellow-ish color. Looking at that and the BWD, they look to be the exact same part. Even the "MADE IN USA" imprint is identical between the two.
Author:  SlantSixDan [ Thu Aug 30, 2007 8:26 am ]
Post subject: 
You may want to try out an AC-Delco CV761C valve, if you can find one. RockAuto claim to have it for $3.30; maybe you can call around and find it locally. If they're still selling the valve they were not long ago, it's a totally different design, and you may find it more rattleproof!
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