blow by

Old 03-17-2008, 06:31 PM
  #1  
arobunson
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Default blow by

i have a sbc 408 with lot of blow back pressure, motor is kind of new just been together for 3 months lot of white smoke coming from breather cap what could this be thanks
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Old 03-17-2008, 06:51 PM
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bjuice
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Its oil getting past your rings..some HP Race motors are built loose and could possible have some minor blow by....thats why a vaccum pump is highly recommended/required..

if you do not have $600.00 to invest in a vaccum pump..at least install some e-vac tubes in the headers

hard to tell by internet how bad your blow-by is...so i am just making a general statement here..

but its oil getting thru

Brian
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Old 03-17-2008, 08:55 PM
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zipper06
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White smoke may indicate a water leak, being it's a 400 blk. they are notorious for blown head gaskets. Have you noticed any milking of the oil?

JMO

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Old 03-18-2008, 01:26 AM
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arobunson
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no water in oil thanks
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Old 03-18-2008, 05:45 AM
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400 blocks if they are not plate honed with the same hardware it will show alot of blow by and if your building a lot of cylinder pressure its even worse.

Do a leak down test.
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Old 03-21-2008, 08:31 PM
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arobunson
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ok compression check #1-190, #3-135,#5-0, #7-230, #2-220, #4-225, #6-220, #8-230 could it be rings or head problem
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Old 03-21-2008, 09:20 PM
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hink
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Originally Posted by arobunson
ok compression check #1-190, #3-135,#5-0, #7-230, #2-220, #4-225, #6-220, #8-230 could it be rings or head problem
You really need to do a leak down test!!!!!!!!
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Old 03-21-2008, 11:01 PM
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cepx111
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Take the head off on the drivers side, the problem should be quite evident since you have "ZERO" compression on number 5 cylinder.
My money has it that you have a hole in the top of your piston.
Goodluck, Charles
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Old 03-22-2008, 05:28 AM
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hink
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Originally Posted by arobunson
ok compression check #1-190, #3-135,#5-0, #7-230, #2-220, #4-225, #6-220, #8-230 could it be rings or head problem
You maybe looking at a bent valve!!!!!!
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Old 03-22-2008, 08:04 AM
  #10  
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Default re; blowby

I once forgot to install the #5 piston, but I knew right off, somthing was amiss, rod made a terrible clatter.
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