oil spitting LT1 (crank case pressure issue)
10-05-2009, 02:19 AM
#1
oil spitting LT1 (crank case pressure issue) Ok, I've searched the boards on crank case issues and I've educated myself a bit on the PCV systems but I've tried a few different setups and I'm still in the dark.
My car has had crank case pressure problems since I built it. Whenever I get on it, oil will spew out of the valve cover cap, and out of the vents in the rear of the covers.
First I put breathers there, looked great, but oil still spewed out.
Then I made a PCV system that routed both valve covers to a T that was at the back of the intake manifold and ran up to the throttle body which pulled the vacuum. (current setup still throwing up oil)
What I'm assuming now is that the hoses I've used are just too big and I'm not getting any vacuum on the valve covers. I think I'm going to go back to the stock PCV hose to the passenger side cover and run a breather on the drivers side valve cover.
If anyone can shed a little more light or insight it'd be greatly appreciated. I'd really like to cut down on my oil consumption. I know LT1s are notorious for having this issue but it's still quite irritating and I'm curious to see what other people are doing to help the issue.
My car has had crank case pressure problems since I built it. Whenever I get on it, oil will spew out of the valve cover cap, and out of the vents in the rear of the covers.
First I put breathers there, looked great, but oil still spewed out.
Then I made a PCV system that routed both valve covers to a T that was at the back of the intake manifold and ran up to the throttle body which pulled the vacuum. (current setup still throwing up oil)
What I'm assuming now is that the hoses I've used are just too big and I'm not getting any vacuum on the valve covers. I think I'm going to go back to the stock PCV hose to the passenger side cover and run a breather on the drivers side valve cover.
If anyone can shed a little more light or insight it'd be greatly appreciated. I'd really like to cut down on my oil consumption. I know LT1s are notorious for having this issue but it's still quite irritating and I'm curious to see what other people are doing to help the issue.
10-05-2009, 10:10 AM
#3
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Some builders have to resort to a vacuum pump to handle excessive blow-by. I believe Moroso and others sell the kit.
However, since your blow-by seems to be so great you'd be better off addressing the cause of the problem, which is probably ring seal. There could be a number of different ring issue that cause this:
Wrong rings for the pistons being run (thickness/diameter),
Excessive ring end gaps,
Rings mis-installed (top ring in 2nd groove; ring(s) up-side down,
Cylinder wall hone not correct for the rings being run,
Low tension oil ring set as opposed to standard tension,
Burrs left on the ends of the rings after custom gapping,
Incorrect ring gap stagger,
Excessive piston to wall clearance,
Tapered/worn cylinder walls,
probably some others.
As already recommended, you should do a dual gauge leak down test to pin point the cause.
Hope this helps,
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!
However, since your blow-by seems to be so great you'd be better off addressing the cause of the problem, which is probably ring seal. There could be a number of different ring issue that cause this:
Wrong rings for the pistons being run (thickness/diameter),
Excessive ring end gaps,
Rings mis-installed (top ring in 2nd groove; ring(s) up-side down,
Cylinder wall hone not correct for the rings being run,
Low tension oil ring set as opposed to standard tension,
Burrs left on the ends of the rings after custom gapping,
Incorrect ring gap stagger,
Excessive piston to wall clearance,
Tapered/worn cylinder walls,
probably some others.
As already recommended, you should do a dual gauge leak down test to pin point the cause.
Hope this helps,
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!
