madmanadam Posted October 27, 2001 Share Posted October 27, 2001 Hey all. I'm stumped again, whut would cause the PVC valve sqweel like a pig. This is whats going on, when the car gets up to temp, I get this high pitch sqweel, at first could not figure out what it was, thought it was something in the motor or the starter. well I pulled the PCV out of the valve cover and the sqweel went away. I bought a new PVC and it still sqweels. What the heck is going on? This is probably something simple but I just cant figure it out. Could someone explain what is going on? The car is running great but the sqweel is drawing more attention then the car. Thanks, any help would be great. Adam Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 27, 2001 Share Posted October 27, 2001 weard could it have somthing to do with a cloged hose just a poke in the dark Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted October 27, 2001 Share Posted October 27, 2001 PVC is hooked up to a main carb vaccuum port? (ie. can it take the pressure relief) Sounds like excess pressure for either the PVC internally (ie. wrong PVC) or air is blowing off externally creating the squeal. Maybe you could sell it to a honda owner for big $ At least you have a PVC, I swapped valve covers after a cam/head changed once and new ones only had one breather installed....blew the dipstick twice in a row and then clued in...bought an external breather/pvc setup just to get it home (it was a stat holiday/I had to drive it 200km's home) and drove home with big smoke clouds as external piece 'dripped' down to exhaust...slightly nerve racking (& stinky)for my wife following behind in the blue cloud Quote Link to comment Share on other sites More sharing options...
madmanadam Posted October 27, 2001 Author Share Posted October 27, 2001 I have the PVC coming off the manifold. I had it coming off the carb but it did the same thing. All new hoses. The PVC is for a v8 350 is there a diffrents? Adam Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted October 27, 2001 Share Posted October 27, 2001 manifold or carb shouldn't matter as long as both are vaccuum sources which would be obvious. All PVC's I've seen could only be setup one way, I assume yours is similar (ie. it is happily allowing crankcase pressure to pass thru.....and it's not in reverse). I recall over a hundred PN's for PCV's, I just picked a camaro high hp 60's one for myself and it's been fine AFAIK. I can't comment on what's different b/t the different PVC's, perhaps different " pressure opening points/heavier balls....? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 27, 2001 Share Posted October 27, 2001 The dyno boys say that sealing the crankcase and letting the PCV slowly create a vacuum inside the crankcase is good for a tad more horsepower but this isn't very workable on a street car. It sounds to me like you do not have any crossflow ventilation. Does the opposite side valve cover have a oil filler/breather combination, or does it have a sealed cap? You must have a source of filtered fresh air to admit into the engine in order for the PCV to work correctly. The sound you are hearing could well be caused by outside air trying to get into the engine in the only place it can. The PCV grommet. One thing is for sure, you won't have to worry about oil leaks at the main seals! Quote Link to comment Share on other sites More sharing options...
madmanadam Posted October 27, 2001 Author Share Posted October 27, 2001 The engine is a ZZ4 350 355hp, has filer cap on both sides and both have breather holes. Center bolt valve covers. The pvc is one for a standard 350 v8 90 model Thanks Adam Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 27, 2001 Share Posted October 27, 2001 Can you effect any change in the noise by removing the opposite side valve cover filler cap? Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted October 27, 2001 Share Posted October 27, 2001 Heh, have a PCV valve and no vent on the other side. You sure that's needed? Modern EFI cars have sealed crankcases and PCV valves don't they? I'd have to wonder WHERE this squeel is coming from. Removing the PCV stops it but is the PCV the source of the noise or the cause? If the PCV is causing vac in th ecrankcase and somehting isn't quite sealed then I'd think THAT might be where the actual noise is coming from? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 28, 2001 Share Posted October 28, 2001 "Heh, have a PCV valve and no vent on the other side. You sure that's needed? Modern EFI cars have sealed crankcases and PCV valves don't they?" Modern crankcases are "vented" but not directly to the atmosphere. When differences in pressure (vacuum) permits, air from the induction system is routed into the crankcase. This effectively "seals" the crankcase vapors from escaping into the air. The standard Z L28 has a large vent line which goes from the throttle body to the top of the valve cover. This is by definition a sealed system, but clearly it is vented. I have heard PCV valves buzz a bit when the vent line is temporarily blocked off during emision testing, but a squeal sounds more like air whistling through a small opening. If this is true, the question is again, Why? If the system is truly vented to the atmosphere at the oil fill caps, such an event would never happen, which begs the obvious. Is it truly vented? Removing the oil cap during an episode of this squealing would answer the vent question for sure. If the sound is unchanged by removing the cap, then venting is not the problem. When the PCV is removed and the noise stops, what happens if the vent opening in the PCV is sealed manually? Does the noise return? The next time the noise is heard, try carefully squirting a small amount of engine oil arount the PCV grommet. Watch to see if it is drawn into the motor. Quote Link to comment Share on other sites More sharing options...
madmanadam Posted November 5, 2001 Author Share Posted November 5, 2001 The squeel is gone for now, I put a breather cap/PVC on one side and another PVC on the other side. Drove the car and about a mile I started to get a slight noise, but not as loud. I unscrewed the oil filler cap and removed the rubber o-ring and the squeel went away, wierd. Went to a auto shop to find a breather that would fit in the filler hole but could not find one that would fit, the hole size is diffrent (2.33). It sounds like the squeel is gone for now. Drove the car for about 100 miles yesterday with no squeel . Got hit with rain and no top never rains in Washington. Adam Quote Link to comment Share on other sites More sharing options...
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