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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: SFord on November 22, 2008, 07:39:13 pm

Title: 1984 k20 4x4 350 blow by question
Post by: SFord on November 22, 2008, 07:39:13 pm
Im not sure what this is,but I have a smoky mist coming from the tube that comes from my valve cover and goes to the bottom of my breather. What causes this? I know it cant be good.Anything yall know that I can do to fix it,cheap n easy? I aint no mechanic,but can pull off a little shade tree stuff.By the way, I got a 350,aluminum intake w/4 bbl holley.It has a fairly lumpy idle,but I dont know what cam specs are.Its got the double hump heads,but I bought it like it is,so thats about all I know about it. Any help will be preciated.Thanks.
Title: Re: 1984 k20 4x4 350 blow by question
Post by: Lt.Del on November 22, 2008, 08:24:31 pm
Change your PCV valve recently?
Title: Re: 1984 k20 4x4 350 blow by question
Post by: SFord on November 22, 2008, 08:32:41 pm
I havent tried yet,but I will tomorrow. Thanks.
Title: Re: 1984 k20 4x4 350 blow by question
Post by: SFord on November 23, 2008, 01:00:51 pm
new pcv valve,still got blow by
Title: Re: 1984 k20 4x4 350 blow by question
Post by: choptop on November 23, 2008, 01:29:22 pm
worn valve guides or rings possibly. How bad is it and how many miles do you have on it?
Title: Re: 1984 k20 4x4 350 blow by question
Post by: SFord on November 23, 2008, 03:17:24 pm
I aint sure as to the miles,but would guess around 60k on engine. The blow by is moderate,but it aint lost any power.
Title: Re: 1984 k20 4x4 350 blow by question
Post by: TexasRed on November 23, 2008, 09:44:57 pm
When's the last time's the oil's been changed? Have you tried 20w50?
Title: Re: 1984 k20 4x4 350 blow by question
Post by: VileZambonie on November 23, 2008, 09:46:34 pm
Do a dry and wet compression test
Title: Re: 1984 k20 4x4 350 blow by question
Post by: SFord on November 24, 2008, 12:13:10 pm
oil has been changed bout 1k ago. I dont know the difference on them tests vile,can you elaborate?
Title: Re: 1984 k20 4x4 350 blow by question
Post by: frogman68 on November 24, 2008, 12:16:56 pm
Quote from: SFord on November 24, 2008, 12:13:10 pm
oil has been changed bout 1k ago. I dont know the difference on them tests vile,can you elaborate?

Dry is just a regular compression test

Wet is when you squirt some oil in the cylinder than run the compression test.
Title: Re: 1984 k20 4x4 350 blow by question
Post by: SFord on November 24, 2008, 12:18:41 pm
ok. I aint done either,but this gives me something to go on.Will post after test,thanks.
Title: Re: 1984 k20 4x4 350 blow by question
Post by: Donut on November 24, 2008, 05:45:03 pm
After re-reading your engine description, do you still have the OEM valve covers on there? 
It just clicked into my head that some aftermarket covers don't have the baffles in the oil breather holes.  This could cause oil to migrate up.
Title: Re: 1984 k20 4x4 350 blow by question
Post by: SFord on November 24, 2008, 05:58:13 pm
The valve covers are stock.Do I need aftermarket v.covers?
Title: Re: 1984 k20 4x4 350 blow by question
Post by: Donut on November 24, 2008, 06:48:23 pm
No, I was just saying some of the aftermarket valve covers didn't have the oil baffles in them.

FWIW, the blowby in mine was so bad that I left the air tube and filter off the air cleaner, and it wasn't long before my windshield was covered in a fine film of oil.  She was smoking out the breather tube bad enough it would put an old Mack to shame. ;D