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Author Topic: 1984 k20 4x4 350 blow by question  (Read 7558 times)

Offline SFord

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1984 k20 4x4 350 blow by question
« 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.
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Offline Lt.Del

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Re: 1984 k20 4x4 350 blow by question
« Reply #1 on: November 22, 2008, 08:24:31 pm »
Change your PCV valve recently?
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Offline SFord

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Re: 1984 k20 4x4 350 blow by question
« Reply #2 on: November 22, 2008, 08:32:41 pm »
I havent tried yet,but I will tomorrow. Thanks.
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Offline SFord

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Re: 1984 k20 4x4 350 blow by question
« Reply #3 on: November 23, 2008, 01:00:51 pm »
new pcv valve,still got blow by
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Offline choptop

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Re: 1984 k20 4x4 350 blow by question
« Reply #4 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?
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Offline SFord

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Re: 1984 k20 4x4 350 blow by question
« Reply #5 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.
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Offline TexasRed

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Re: 1984 k20 4x4 350 blow by question
« Reply #6 on: November 23, 2008, 09:44:57 pm »
When's the last time's the oil's been changed? Have you tried 20w50?
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Offline VileZambonie

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Re: 1984 k20 4x4 350 blow by question
« Reply #7 on: November 23, 2008, 09:46:34 pm »
Do a dry and wet compression test
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Offline SFord

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Re: 1984 k20 4x4 350 blow by question
« Reply #8 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?
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Offline frogman68

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Re: 1984 k20 4x4 350 blow by question
« Reply #9 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.
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Offline SFord

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Re: 1984 k20 4x4 350 blow by question
« Reply #10 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.
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Offline Donut

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Re: 1984 k20 4x4 350 blow by question
« Reply #11 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.
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Offline SFord

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Re: 1984 k20 4x4 350 blow by question
« Reply #12 on: November 24, 2008, 05:58:13 pm »
The valve covers are stock.Do I need aftermarket v.covers?
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Offline Donut

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Re: 1984 k20 4x4 350 blow by question
« Reply #13 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
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'73 Chevy K-20 ***SOLD***
350/tbh350/np205
My plow was half price if i took the truck with it.

'86 C-30 dually, 454/tbh400
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