Help with oil leak in a sbc

Old 04-20-2010, 03:51 AM
  #1  
allchevys
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Default Help with oil leak in a sbc

I have just rebuilt a motor (a sbc) and I found a leak in the bottom end. It done this before I redone the motor and its doing it again. when the rpm reaches 5500 and above it spays oil on the exhaust and fills the inside of the car with smoke. I narrowed it down to the oil filter area. its dry everywhere but there is a drip on the bottom of the filter. I have put 4 differant types of filter on this and everyone does the same thing. Im at a lose now. if you drive it down the road and dont get on it its fine.
Anyone got any ideas on what to do.
Thanks
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Old 04-20-2010, 04:10 AM
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ztlonewolf
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try checking the area where the filter comes in contact with the block,could be something keeping the filter from gettting a good seal.

spreading a little bit of oil on top of the filter prior to installation will help it seal better
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Old 04-20-2010, 04:17 AM
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allchevys
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I checked it out before and the area is clean (scotch brite) and I did put a little oil on the seal and I never over tighten the filters. hand tight and a 1/2 turn. getting very frustrated with it now. I never had this problem before.
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Old 04-20-2010, 07:17 AM
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oldandtired
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Do you have the filter bypass blocked?
Dave
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Old 04-21-2010, 04:47 AM
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allchevys
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no its open. Im changing the adapter plate that the filter screws onto (I have cleaned the old one and didnt see any defects) But I figure its worth changing just to see what happens. thats the only thing I didnt change when the motor was redone.
Thanks for you input on this.
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Old 04-21-2010, 09:41 AM
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allchevys
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Well just changed filter and adapter and took it for a spin when I hit 6800 rpm and the shift light came on the oil filled the car with smoke again. Im lost now and Im giving up. its around the filter area but Ill be SOB if I can find out what it is :cry:
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Old 04-21-2010, 11:09 AM
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johnracer
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Question.....how is the crankcase vented? Maybe it's building pressure and leaking at the weakiest point. Just a thought
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Old 04-21-2010, 12:36 PM
  #8  
allchevys
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I have an evacuation tube from the drivers side valve cover down to the header and a pcv valve on the pass. side Im thinking its a preasure thing but I dont know what to do to stop this. Not to mention I cant see anything leaking at the pan or the rear main
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Old 04-21-2010, 04:02 PM
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gnsrule
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Tighten up the filter a tick more? Try a full turn, the worst you get is a PITA filter to get off. I had 1 blow one time, fortunatly it was on the dyno and not the track. That wouldnt be good.

Craig
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Old 04-21-2010, 04:11 PM
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gnsrule
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BTW, You sure its not a valve cover leaking ? When you hit 6k the fan is blowing it off the head and onto the exhaust ?
With a PCV, when your at WOT it only sees low to no vacuum, with only one evacuation tube, you might not have enuff evacuation to handle the blow by. Ditch thew pcv and run a breather and see what happens, or ditch the evac tube for a breather. How tight is the motor ? If the blow by is excessive, nothings gonna fix it except a bag of cash.

Craig
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