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05-08-2007, 10:11 AM
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#1 |
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Registered User
Join Date: Apr 2000
Location: Chester County PA, USA
Posts: 1,228
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oil coming out PVC?
My 86 GMC 3/4 ton 4x4 with a 350 is pushing out oil thru the PCV . I replaced the PCV valve and that didn't help. So i thought mabey the oil return holes in the head were mabey cloged up. so i pulled the valve cover,(it has center bolt type) and everything was fine. Anybody elese have this problem? The oil is getting all over the place.
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72 k/10 short wideside 72 k/5 Blazer 72 K/5 Blazer - obstacle course racer 72 custom/10 8' bed 70 K/5 Blazer 67 C-30 GMC Flat bed 86 GMC K2500 Plow Truck 85 GMC K3500 84 M1008 85 M1008 77 G30 Motor Home 72 Sears 12hp Tractor Glenmoore, Pennsylvania Last edited by OLDCHEV4X4; 05-08-2007 at 10:59 AM. |
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05-08-2007, 12:35 PM
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#2 |
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glamoros piece o' lowlife
Join Date: Mar 2007
Location: Redford, MI
Posts: 1,164
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Re: oil coming out PVC?
How is yer compression (of the cylinders)? There;s only one thing that'd cause such an excessive oil suction at the PCV, and that's blow-by - under normal operation of a good-condition engine the oil itself doesn't get hot enough to build up the massive crankcase pressure that is needed for it to start spitting out... Go to parts store and rent a compression tester, then post yer findings.
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The more I drink, the more I drink, the more I drink... diesel, reg cab, long bed, 4 across the rear, single stack, wooden stakes, and lotsa lights - the Hay Express |
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05-08-2007, 12:40 PM
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#3 |
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Registered User
Join Date: Apr 2000
Location: Chester County PA, USA
Posts: 1,228
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Re: oil coming out PVC?
I got compression tester. How many psi should i have in a high milage motor?
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72 k/10 short wideside 72 k/5 Blazer 72 K/5 Blazer - obstacle course racer 72 custom/10 8' bed 70 K/5 Blazer 67 C-30 GMC Flat bed 86 GMC K2500 Plow Truck 85 GMC K3500 84 M1008 85 M1008 77 G30 Motor Home 72 Sears 12hp Tractor Glenmoore, Pennsylvania |
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05-08-2007, 02:25 PM
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#4 |
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Registered User
Join Date: Feb 2007
Location: Austin, TX
Posts: 3,930
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Re: oil coming out PVC?
I've never compression tested a Chevy 350 but I did compression test the 4 banger in my friends Honda. They were all around 120-130 PSI with about 130K miles on the clock.
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05-08-2007, 06:19 PM
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#5 |
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glamoros piece o' lowlife
Join Date: Mar 2007
Location: Redford, MI
Posts: 1,164
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Re: oil coming out PVC?
Yah, I think 120-130 is about right.
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The more I drink, the more I drink, the more I drink... diesel, reg cab, long bed, 4 across the rear, single stack, wooden stakes, and lotsa lights - the Hay Express |
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05-08-2007, 08:13 PM
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#6 |
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Registered User
Join Date: Feb 2007
Location: Westfield, Tioga County) Pennsylvania
Posts: 113
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Re: oil coming out PVC?
Just did a compression test on 87 to find an ailing cylinder. I tested three cylinders until I came across the bad one. They were all +/- 140#.
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Ironhead Mike '68 Panel 402BB '84 Shortbox 4X4 '85 Blazer '97 Silverado Ext. Cab |
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05-08-2007, 11:52 PM
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#7 |
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Registered User
Join Date: Apr 2007
Location: ohio
Posts: 43
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Re: oil coming out PVC?
You probably have blowby on all cylinders.
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05-09-2007, 06:49 AM
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#8 |
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The Crazy Machanic
Join Date: Jan 2007
Location: Nokesville Va
Posts: 1,437
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Re: oil coming out PVC?
I have the same problem at running my trucks psi at a stop is about 30 psi and at go it 38psi if this helps any. I have the same isssue with the oil coming out at the top i was thinking if siliconing it, but im running an after market pvc cover thats crome from autozone so i think that might be my issue. Cause the fluid is not come the the grommit at the valve cover it coming from the one that seal around the top of the pvc to the chrom cap.
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*1986 Sliverado longbed 400 small block mean as hell, 700r4 trans (5 speed coming one day)  * 1970 chevelle 2dr sedan Latest update June 24 2007.  *1957 4 door stationwagon - pink all original needing a good restore (body great, floors bad)  newest additions 1965 shortbed fleet great granddads. Been told im nuts to bring it back from the dead (still going to happen) plans-all stock with a turbo 292 inline 3 speed column shift. and thats it big block 427 and 5 speed trans and ford 9 inch theyhave no home yet thinking what to put them in and a 79 c60 trash truck um no idea i have one
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05-09-2007, 10:22 AM
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#9 | |
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Registered User
Join Date: Feb 2005
Location: Alberta
Posts: 248
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Re: oil coming out PVC?
Quote:
Anyway they tore down the motor and couldnt find anything wrong with it. After months of me *****ing they finally replaced the motor with another new crate motor. This one had the right harmonic balancer! Anyway the new lm1 works great. |
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05-09-2007, 12:34 PM
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#10 |
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Registered User
Join Date: Apr 2000
Location: Chester County PA, USA
Posts: 1,228
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Re: oil coming out PVC?
Thanks for the reply's guys. I will do a compression check and let you know whats up.
But it dosent use any oil and it dosent smoke out the exaust, and broken or worn out rings would make oil smoke. Right?
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72 k/10 short wideside 72 k/5 Blazer 72 K/5 Blazer - obstacle course racer 72 custom/10 8' bed 70 K/5 Blazer 67 C-30 GMC Flat bed 86 GMC K2500 Plow Truck 85 GMC K3500 84 M1008 85 M1008 77 G30 Motor Home 72 Sears 12hp Tractor Glenmoore, Pennsylvania |
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05-09-2007, 08:53 PM
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#11 |
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Parts and more parts
Join Date: Nov 2003
Location: Lebo, Kansas (middle of nowhere
Posts: 6,821
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Re: oil coming out PVC?
You could have a bad valve guide. You are definitely getting some blow by.OR
Just how do you have your PCV set up on the truck? Do you have a positive ventialtion setup on theengine or are you just running ventilated caps on the valve covers. The positive design would be that you have a PCV valve connected toyour intake m anifold and the other valve cover has either a ventilated cap or a hose attached to the air cleaner. (this is the cleanest way) If you are running just ventilated caps to the atmosphere, then the vapors will pump up in the block and push out onto your engine. |
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05-10-2007, 08:41 AM
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#12 |
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Registered User
Join Date: Apr 2000
Location: Chester County PA, USA
Posts: 1,228
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Re: oil coming out PVC?
I think i got it..... My 97 truck broke down yesterday and i had to tow with the 86. So i pulled the pipe off on the opposite side valve cover and there was a bunch of oily crap in there. I cleaned it out, hooked up the trailer and hoped for the best. I was stressed out obviously because i had one truck broke down and my best tow truck about to break down. And i had to tow over Welch mountain.
I made it back and there was alot less oil puking out than before. So i think i'm gonna pull that other valve cover and check for crud. Thanks for all the help guys! 
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72 k/10 short wideside 72 k/5 Blazer 72 K/5 Blazer - obstacle course racer 72 custom/10 8' bed 70 K/5 Blazer 67 C-30 GMC Flat bed 86 GMC K2500 Plow Truck 85 GMC K3500 84 M1008 85 M1008 77 G30 Motor Home 72 Sears 12hp Tractor Glenmoore, Pennsylvania |
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05-10-2007, 02:23 PM
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#13 |
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junk collector
Join Date: Dec 2004
Location: above Baton Rouge, LA
Posts: 693
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Re: oil coming out PVC?
Been a whilesince I messed with a carbed motor, but in tbi vehicles it is very common for the port on the tbi unit to clog up and cause excessive crancase pressures. I had a 4.3 blow out valve cover gaskets and a oil pan gasket due to that pcv post plugging.
Check the whole system, anywhere it is baffled or has a hose or such can crud up.
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'87/89/76 K5 in progress '99 K2500 short crew '91 camaro rs '98 jeep tj '52 willys cj3a |
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